Overview of system variables|V4.3.3|OceanBase Database| docs|Distributed Database

This topic describes the system variables of OceanBase Database based on the functions of the system variables.

Global level

Variable	Description
validate_password_check_user_name	Specifies whether a user password can be the same as the username.
validate_password_length	Specifies the minimum length of a user password.
validate_password_mixed_case_count	Specifies the minimum number of uppercase and lowercase letters in a user password.
validate_password_number_count	Specifies the minimum number of digits in a user password.
validate_password_policy	Specifies the password check strategy.
validate_password_special_char_count	Specifies the minimum number of special characters in a user password.
ob_tcp_invited_nodes	Specifies the IP address list of a tenant, which serves as the IP address whitelist. The IP address list supports the percent sign (%), hyphen (-), and IP address. Multiple IP addresses are separated with commas (,). The IP address list supports IP address list matching, mask matching, and fuzzy matching.
default_password_lifetime	Specifies the password expiration period.
block_encryption_mode	Specifies the encryption algorithm used in the AES encryption and decryption functions.
sql_safe_updates	Specifies whether to enable the MySQL SQL security mode. The default value is `OFF`.
super_read_only	Specifies the read/write permissions of the database. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.

Variable name	Description
version_comment	Displays the version information of the OBServer node.
version	Displays the server version number.
ob_last_schema_version	Specifies the latest schema version used in the session.
ob_proxy_global_variables_version	Specifies the latest version of global variables that the OBServer node returns to the OBproxy.
ob_enable_transmission_checksum	Specifies whether to perform packet checksum verification between the obproxy and the OBServer node. This setting takes effect immediately.
ob_compatibility_control	Controls the behavior mode when compatibility conflicts occur between MySQL 5.7 and MySQL 8.0.
ob_compatibility_version	Specifies the OceanBase Database version that the product is compatible with when its behavior changes.
ob_security_version	Specifies the OceanBase Database version that the security feature is compatible with. The compatible version is specified when the tenant is created and cannot be modified after the tenant is created.
old_alter_table	Specifies whether to use the ALTER TABLE syntax and operation mode of the earlier version. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Variable name	Description
debug	Specifies the debug options. The default value is `d:t:i:o,/tmp/mysqld.trace`. Note This variable is supported only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
debug_sync	Specifies the synchronization points when Debug is enabled. The default value is an empty string. Note This variable is supported only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
ob_global_debug_sync	Specifies the synchronization points when Debug is enabled. This variable differs from `debug_sync` in that setting this variable affects all sessions.

Case sensitivity

Variable name	Description
lower_case_table_names	Specifies whether to use case-sensitive table names.

Variable name	Description
query_cache_size	Specifies the memory size allocated for storing the results of historical queries, which is the unused memory.
query_cache_type	Specifies the query cache type.
ob_query_timeout	Specifies the query timeout period.
is_result_accurate	When a query contains the `topk` hint, `is_result_accurate` indicates whether the result is accurate.
net_buffer_length	Specifies the maximum size of an SQL query that an OBServer node can accept.
read_only	Specifies whether the tenant is in read-only mode.
ob_read_consistency	Specifies the read consistency level.
ob_max_read_stale_time	Specifies the maximum latency threshold (in microseconds) for weak-consistency reads.
net_read_timeout	Specifies the number of seconds that a connection waits for other data to be read before it is interrupted.
net_write_timeout	Specifies the number of seconds that a connection waits for block writes before it is interrupted.
ob_enable_index_direct_select	Specifies whether to allow users to directly query index tables.
ob_enable_aggregation_pushdown	Specifies whether to allow aggregation operations to be pushed down.
ob_enable_jit	Specifies the JIT execution engine mode.
sql_throttle_network	Specifies the request queuing time. If the queuing time exceeds or equals this value, queries are not executed.
parallel_servers_target	Specifies the large query queuing conditions on each server.
cte_max_recursion_depth	Specifies the maximum recursion depth of common table expressions (CTEs). The server terminates any operation that exceeds this CTE value.
regexp_stack_limit	Specifies the maximum available memory size for the internal stack used in regular expression matching operations.
regexp_time_limit	Specifies the time limit for regular expression matching operations.
long_query_time	Specifies the threshold for slow queries.

Event Scheduler

Variable	Description
event_scheduler	Specifies whether the event scheduler is enabled and running on the server.

Variable	Description
ob_create_table_strict_mode	Specifies the strict mode for table creation.
ob_default_replica_num	Specifies the default number of replicas for each table in a cluster.
master_info_repository	Specifies whether to store replica metadata in an InnoDB table of the MySQL system database or as a file in the data directory. The default value is `FILE`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
replication_optimize_for_static_plugin_config	Specifies whether to enable shared locks to improve the performance of semi-synchronous replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
replication_sender_observe_commit_only	Specifies whether to enable restricted callbacks to improve the performance of semi-synchronous replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_semi_sync_slave_enabled	Specifies whether to enable semi-synchronous replication on the replica. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_semi_sync_slave_trace_level	Specifies the debugging trace level for semi-synchronous replication on the replica. The default value is `32`, which indicates the network wait level. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_stop_slave_timeout	Specifies the time to wait for more data or a heartbeat signal from the source before the STOP SLAVE operation times out, in seconds. The default value is `31536000`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_checkpoint_group	Specifies the maximum number of transactions that can be processed by multi-threaded replication before a checkpoint operation is called to update the progress status. The default value is `512`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_checkpoint_period	Specifies the maximum time allowed, in milliseconds, between the start of a checkpoint operation and the start of the next one to update the progress status of multi-threaded replication. The default value is `300`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_compressed_protocol	When both the source and the replica support compression, specifies whether to use the compression of the source or the replica. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_exec_mode	Specifies how the replication threads resolve conflicts and errors during replication. Setting this variable to `IDEMPOTENT` suppresses errors for duplicate and not-found keys. Setting this variable to `STRICT` does not suppress errors for duplicate and not-found keys. The default value is `STRICT`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_max_allowed_packet	Specifies the maximum size of data packets for the replication SQL and I/O threads, in bytes. The default value is `1073741824`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_net_timeout	Specifies the time to wait for more data or a heartbeat signal from the source before the replica considers the connection to be disconnected, aborts reading, and attempts to reconnect, in seconds. The default value is `60`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_parallel_type	Specifies the type of parallelism to use for executing replication transactions when multi-threaded replication is enabled. The default value is `DATABASE`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_parallel_workers	Specifies the number of threads to use for parallel execution of replication transactions. The default value is `0`, which disables parallel execution of replication transactions. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_pending_jobs_size_max	For multi-threaded replication, specifies the maximum length of the work queue for events that have not been applied, in bytes. The default value is `16777216`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_preserve_commit_order	For multi-threaded replication, specifies whether to commit transactions in the order of the relay logs. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_rows_search_algorithms	Specifies the algorithm that the replica uses to search for related rows. The default value is `TABLE_SCAN,INDEX_SCAN`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_sql_verify_checksum	Specifies whether to use the checksums read from the relay logs to verify data during replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_transaction_retries	Specifies the number of times the system automatically re-executes a transaction when the replication SQL thread fails due to a deadlock or the transaction execution time exceeds the value specified by the `innodb_lock_wait_timeout` variable. The default value is `10`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_type_conversions	Specifies the type conversion mode on the replica when using row-based replication. The default value is empty, which specifies to prohibit type conversion between the source and the replica. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
sql_slave_skip_counter	Specifies the number of events to skip from the source for the replica. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
skip_slave_start	Specifies whether to skip the startup of the replication thread when the replica server starts. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.
slave_load_tmpdir	Specifies the directory name for temporary files created by the replica. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.
slave_skip_errors	Specifies which errors to skip during replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.

Variable name	Description
rpl_semi_sync_master_enabled	Specifies whether to enable semi-synchronous replication on the source. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_timeout	Specifies the time in milliseconds that the source waits for a replica to confirm the transaction after the transaction is committed. The default value is `10000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_trace_level	Specifies the debug trace level for semi-synchronous replication on the source. The default value is `32`, which indicates the network wait level. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_for_slave_count	Specifies the number of replica acknowledgments that each transaction must receive before the source continues. The default value is `1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_no_slave	Specifies whether to wait for the timeout period specified by the `rpl_semi_sync_master_timeout` variable when the number of replicas falls below the value set by the `rpl_semi_sync_master_wait_for_slave_count` variable. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_point	Specifies the point in time at which the semi-synchronous source waits for replica acknowledgment of transaction reception before returning the status to the client that committed the transaction. The default value is `AFTER_SYNC`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Variable name	Description
recyclebin	Specifies whether to enable the recycle bin feature.
ob_enable_truncate_flashback	Specifies whether to enable flashback for table truncation.

Variable name	Description
ob_enable_plan_cache	Specifies whether to enable the plan cache.
ob_plan_cache_percentage	Specifies the percentage of memory available to the plan cache out of the total memory of the tenant.
ob_plan_cache_evict_high_percentage	Specifies the percentage of memory at which plan cache eviction is triggered, relative to the absolute maximum memory.
ob_plan_cache_evict_low_percentage	Specifies the percentage of memory at which plan cache eviction is stopped, relative to the absolute maximum memory.
ob_bnl_join_cache_size	Specifies the number of data records to cache for each batch in a Batch Nest Loop Join operation.
stored_program_cache	Specifies the number of cached stored procedures and functions. The default value is `256`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.
table_definition_cache	Specifies the number of memory spaces for caching table definitions. The default value is `-1`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Variable name	Description
interactive_timeout	Specifies the number of seconds that the server waits for activity before closing an interactive connection.
wait_timeout	Specifies the number of seconds that the server waits for activity before closing a non-interactive connection.
group_concat_max_len	Specifies the maximum length of the result of the `GROUP_CONCAT()` function.

Variable name	Description
innodb_change_buffering_debug	Specifies the debugging level for changing the InnoDB buffer. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_compress_debug	Specifies the debugging level for adjusting and controlling the compression behavior. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_disable_resize_buffer_pool_debug	Specifies whether to enable the adjustment of the InnoDB buffer pool size. The default value is `1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_fil_make_page_dirty_debug	Specifies the number of pages to dirty in the InnoDB buffer for debugging. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_limit_optimistic_insert_debug	Specifies the number of records on each B-tree page. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_merge_threshold_set_all_debug	Specifies the page full percentage of index pages. The default value is `50`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_saved_page_number_debug	Specifies the number of page numbers to save in the InnoDB buffer for debugging. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_trx_purge_view_update_only_debug	Specifies the debugging level for updating only the purge view during transaction cleanup. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_trx_rseg_n_slots_debug	Specifies the number of slots in the transaction rollback segment (transaction rollback segment). Each slot stores the rollback information of a transaction. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_stats_persistent	Specifies whether to persist the InnoDB index statistics to the disk.
innodb_force_recovery	Specifies the crash recovery mode for repairing the data of the damaged InnoDB storage engine. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_replication_delay	Specifies the delay of the replication threads on the replication server when the value of the `innodb_thread_concurrency` variable is reached, in milliseconds. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_large_prefix	Specifies whether to allow index key prefixes longer than 767 bytes (up to 3072 bytes) for InnoDB tables that use the DYNAMIC or COMPRESSED row format. The default value is `ON`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_sort_buffer_size	Specifies the size of the buffer for sorting operations. The default value is `1048576`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
default_tmp_storage_engine	Specifies the default temporary table storage engine. The default value is `InnoDB`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_tmpdir	Specifies the directory for storing temporary files of InnoDB. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
mecab_rc_file	Specifies the path of the MeCab configuration file. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_temp_data_file_path	Specifies the storage path for temporary data files of InnoDB. The default value is `ibtmp1:12M:autoextend`, which indicates that InnoDB will use a temporary data file named ibtmp1, with an initial size of 12 MB, and the file will automatically expand as needed to store additional temporary data. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_data_file_path	Specifies the storage path and filename for InnoDB data files, with the default value of `ibdata1:12M:autoextend`. This indicates that InnoDB will use a temporary data file named ibdata1, with an initial size of 12 MB, and the file will automatically expand as needed to store additional temporary data. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_data_home_dir	Specifies the root directory for InnoDB data files. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.

Variable	Description
ob_capability_flag	The capabilities of an OBServer node. This variable is used to negotiate capabilities with the proxy. It informs the proxy of the features supported by the current OBServer node.
ob_compatibility_mode	The compatibility mode of the tenant.
ob_route_policy	The routing strategy for selecting a data replica on an OBServer node.
performance_schema	Specifies whether to support queries for performance information. The default value is `OFF`. Note This variable is only for compatibility with MySQL 8.0. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
resource_manager_plan	The resource management plan. If you specify different plans, different CPU quotas are used to limit user activities in a resource group.
license	The type of the license.
ob_proxy_partition_hit	Specifies whether to send SQL statements to the OBServer node that hosts the primary partition where the data is located.
ob_org_cluster_id	The `CLUSTER_ID` of the OceanBase cluster.
server_uuid	The UUID of the OBServer node.
default_storage_engine	The default storage engine of the OBServer node.
slave_allow_batching	Specifies whether to enable batch updates for the replication thread. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Variable	Description
datadir	The local disk path for storing data.
plugin_dir	The path for storing plugin DLLs.
secure_file_priv	The path that can be accessed when importing or exporting to a file.
ob_enable_hash_group_by	Specifies whether to enable Hash Group by.

Variable	Description
delay_key_write	Specifies whether to delay the writing of index keys for MyISAM tables. The default value is `ON`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_buffer_size	Specifies the size of the key buffer for the MyISAM storage engine. The default value is `8388608`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_age_threshold	Specifies the threshold for degrading the hot sublists of the key cache to the warm sublists. A lower value means faster degradation. The default value is `300`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_block_size	Specifies the size of each block in the MyISAM key cache. The default value is `1024`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_division_limit	Specifies the division limit for the MyISAM key cache. The default value is `100`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
max_seeks_for_key	Specifies the maximum number of address operations performed in a MyISAM query. The default value is `18446744073709551615`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.

Temporary files

Variable	Description
max_tmp_tables	The maximum number of temporary tables that a user session can hold simultaneously. The default value is `32`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not trigger an error but also does not take effect.

Memory

Variable	Description
ob_sql_work_area_percentage	The percentage of tenant memory that is allocated for SQL execution.
ob_sql_audit_percentage	The maximum percentage of tenant memory that is allocated for SQL audit.
ob_reserved_meta_memory_percentage	The percentage of tenant memory that is reserved for storing meta-related structural information.
ob_temp_tablespace_size_percentage	The percentage of tenant memory that is allocated for temporary tablespaces.

System logs

Variable	Description
binlog_row_image	Specifies whether to record full-column logs.
ob_enable_show_trace	Specifies whether to use trace logs.
ob_log_level	The log level of the session. If not specified, the system log level is used.
tracefile_identifier	Specifies the content to be added to the log for filtering row iteration trace logs.
master_verify_checksum	Specifies whether to enable checksum verification. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not trigger an error but also does not take effect.

Variable name	Description
innodb_ft_enable_diag_print	Specifies whether to enable or disable diagnostic output for InnoDB full-text indexing. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_num_word_optimize	Specifies the minimum number of words to be processed during an OPTIMIZE TABLE operation. The default value is `2000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_result_cache_limit	Specifies the size of the result cache for InnoDB full-text indexing. The default value is `2000000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_server_stopword_table	Specifies the server stopword table for InnoDB full-text indexing. The default value is `NULL`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_optimize_fulltext_only	Specifies whether to perform an OPTIMIZE TABLE operation only on InnoDB tables that contain FULLTEXT indexes. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_cache_size	Specifies the size of the InnoDB full-text index cache. The default value is `8000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
innodb_ft_sort_pll_degree	Specifies the number of parallel threads for sorting full-text indexes. The default value is `2`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
innodb_ft_total_cache_size	Specifies the total size of the InnoDB full-text index cache. The default value is `640000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
ft_stopword_file	Specifies the path of the file that contains stop words to be excluded. The default value is `built-in`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.

Variable name	Description
runtime_filter_type	Specifies the type of runtime filter for a tenant.
runtime_filter_wait_time_ms	Specifies the maximum wait time for a runtime filter.
runtime_filter_max_in_num	Specifies the number of NDV (number of distinct values) for a runtime in filter.
runtime_bloom_filter_max_size	Specifies the maximum memory size of a runtime Bloom filter, in bytes.

Variable name	Description
avoid_temporal_upgrade	Specifies the behavior of upgrading time-sensitive data (such as dates and times). The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Time zones and dates

Variable name	Description
time_zone	Specifies the time zone for the current tenant session. Valid values are in the offset format, such as `'+08:00'`, and the region format, such as `Asia/Shanghai`.
timestamp	`TIMESTAMP` is a timestamp in seconds. This variable affects the result of `select now(6)`.
system_time_zone	Specifies the system time zone of the server.
error_on_overlap_time	Specifies whether to return an error when the time zone overlaps occur.
nls_language	Specifies the default language for database internationalization support. This variable is used to specify the default values for prompts, dates, month names, `NLS_SORT`, and `NLS_DATE_LANGUAGE`.
nls_territory	Specifies the current region for database internationalization support. This variable is used in combination with `nls_language`.
nls_date_language	Specifies the default language for dates in database internationalization support.
nls_calendar	Specifies the calendar system used by the database.
ob_timestamp_service	Specifies the timestamp service to be used.

Variable name	Description
autocommit	Specifies whether to automatically commit a transaction.
tx_isolation	Specifies the transaction isolation level.
ob_proxy_set_trx_executed	Specifies whether to send the `START TRANSACTION Syntax` statement to the OBServer node through obproxy.
ob_early_lock_release	Specifies whether to enable the early lock release (ELR) feature for a transaction. Note This variable is deprecated in V2.2.30. The ELR feature is now controlled by the tenant-level configuration item `enable_early_lock_release`.
ob_trx_idle_timeout	Specifies the transaction idle timeout period, which is the time interval between the execution of two statements in a transaction that exceeds the timeout period.
transaction_isolation	Specifies the transaction isolation level.
transaction_read_only	Specifies whether to allow only read-only transactions.
ob_trx_lock_timeout	Specifies the timeout period for a transaction to wait for a lock.
tx_read_only	Specifies whether to set a transaction to read-only.
ob_trx_timeout	Specifies the transaction timeout period.
ob_trace_info	Specifies whether to pass trace information, which can be persisted to the redo log.

Variable name	Description
ob_enable_sql_audit	Specifies whether to enable the SQL audit feature for the current tenant.

Data types

Variable name	Description
nls_length_semantics	Specifies the length semantics for the CHAR and VARCHAR2 data types.
nls_nchar_conv_excp	Specifies whether to return an error when data is lost during conversion between the NCHAR and NVARCHAR2 data types and the CHAR and VARCHAR2 data types.
nls_numeric_characters	Specifies the characters used for decimal and thousand separators in string representations of numbers.
nls_currency	Specifies the local currency symbol for the `L` format element in the number format.
nls_iso_currency	Specifies the local currency symbol for the `C` format element in the number format.
nls_dual_currency	Specifies the local currency symbol for the `U` format element in the number format.
nls_date_format	Specifies the format for converting the date data type to a string and for implicitly converting a string to a date.
nls_timestamp_format	Specifies the format for converting the TIMESTAMP or TIMESTAMP_LTZ data types to a string and for implicitly converting a string to a TIMESTAMP or TIMESTAMP_LTZ data type.
nls_timestamp_tz_format	Specifies the format for converting the TIMESTAMP_TZ data type to a string and for implicitly converting a string to a TIMESTAMP_TZ data type.
explicit_defaults_for_timestamp	Specifies whether to enable non-standard behavior for the TIMESTAMP data type when handling default values and null values.
log_row_value_options	Specifies whether to enable partial updates for LOBs.
ob_default_lob_inrow_threshold	Specifies the default in-row storage threshold for LOB fields when a table is created.

Variable	Description
connect_timeout	Specifies the connection timeout period.
ob_pl_block_timeout	Specifies the maximum timeout period for PL.
cursor_sharing	Specifies whether to parameterize SQL statements.
have_profiling	Specifies whether performance analysis is supported. The default value is `NO`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query this variable, but cannot set it.
profiling	Specifies whether to enable the statement analysis feature. The default value is `0`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
profiling_history_size	Specifies the number of records to be saved for query performance information. The default value is `15`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_strict_mode	Specifies the SQL check mode for specific syntaxes.
max_connections	Specifies the maximum number of connections for the tenant.
sql_mode	Specifies the SQL mode, which has a significant impact on operations such as data insertion.
sql_quote_show_create	Specifies whether to enable identifier quoting for `SHOW CREATE TABLE` and `SHOW CREATE DATABASE` statements.
ob_enable_rich_error_msg	Specifies whether to display information such as svr_ip, time, and trace_id when an SQL execution error occurs.
sql_throttle_current_priority	Specifies the throttling priority. Only requests from sessions where `sql_throttle_current_priority` is less than `sql_throttle_priority` will be throttled.
sql_throttle_priority	Specifies the throttling priority.
sql_throttle_rt	Specifies the response time (RT) value.
max_allowed_packet	Specifies the maximum size of network packets.
max_user_connections	Specifies the maximum number of connections that a single user can establish with an OBServer node. A value of `0` indicates no limit.
max_sp_recursion_depth	Specifies the maximum number of recursive calls to any specified stored procedure.
sql_select_limit	Specifies the maximum number of rows that a single SELECT query can return.
max_connections	Specifies the maximum number of connections for the tenant.
ob_enable_blk_nestedloop_join	Specifies whether to enable block nested loop join.
parallel_max_servers	Specifies the maximum number of threads in the parallel execution (PX) thread pool on each server.

Variable name	Description
metadata_locks_cache_size	Specifies the cache size for metadata locks. The default value is `1024` bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.
metadata_locks_hash_instances	Specifies the number of instances for the metadata lock hash table. The default value is `8`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.

Variable name	Description
foreign_key_checks	Specifies whether to check foreign key constraints during DML or DDL operations.

Variable name	Description
optimizer_use_sql_plan_baselines	Controls whether the optimizer uses plan baselines.
optimizer_capture_sql_plan_baselines	Controls whether to automatically capture new plans to plan baselines.
parallel_degree_policy	Specifies the parallelism selection strategy.
parallel_degree_limit	Specifies the maximum degree of parallelism that the optimizer selects when the auto DOP strategy is used.
parallel_min_scan_time_threshold	Specifies the minimum estimated execution time for parallel processing of base table scans.
optimizer_dynamic_sampling	Controls the level of dynamic sampling.
optimizer_features_enable	Specifies the optimizer features of different OceanBase versions.
ob_enable_transformation	Specifies whether to enable the rewrite feature of the SQL optimizer.
ob_table_access_policy	Controls the optimizer to prefer specific storage formats when generating base table plans.

Auto-increment columns

Variable	Description
auto_increment_increment	Specifies the auto-increment step, which is only used when a MySQL client logs in.
auto_increment_offset	Specifies the starting value of the `AUTO_INCREMENT` column.
last_insert_id	Returns the last auto-increment field value inserted in the current session.
identity	`identity` and `last_insert_id` are synonyms. You can run `select @@identity` to query the value.
sql_auto_is_null	Specifies whether to retrieve the auto-increment column value of the last inserted row.
auto_increment_cache_size	Specifies the number of auto-increment values cached.
div_precision_increment	Specifies the increment of the precision of the result of a division operation based on the precision of the dividend. This is a MySQL-compatible feature.

Character sets and strings

Variable	Description
character_set_client	Specifies the character set for statements sent by the client.
character_set_connection	Specifies the character set for statements received by the server.
character_set_database	Specifies the character set for the default database.
character_set_results	Specifies the character set for converting results or error messages sent to the client.
character_set_server	Specifies the character set for the server.
character_set_system	Specifies the character set used by the server.
collation_connection	Specifies the character set and collation for the connection.
collation_database	Specifies the default character set and collation for creating databases.
collation_server	Specifies the default character set and collation for the server.
character_set_filesystem	Specifies the character set for the file system.
sql_warnings	Controls whether to generate an information string for single-line INSERT statements when an alert is triggered.
init_connect	Specifies the string executed by the server for each client connection, which consists of one or more SQL statements separated by semicolons.
nls_sort	Specifies the collation for the string value.
nls_comp	Specifies the comparison rule for the string value.
nls_characterset	Specifies the default character set for CHAR, VARCHAR2, CLOB, and other data types in the database.
nls_nchar_characterset	Specifies the default character set for NCHAR, NVARCHAR2, and NCLOB data types in the database.

Variable name	Description
group_replication_allow_local_disjoint_gtids_join	Specifies whether to allow a server to join the group if the server has local transactions that are not in the group. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_allow_local_lower_version_join	Specifies whether to allow a server to join the group if the server is running a MySQL Server version that is earlier than the version of other members in the group. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_auto_increment_increment	Specifies the auto-increment value step for each member in the group to ensure that the auto-increment values of the group members are ordered and non-overlapping in multi-primary mode. The default value is `7`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_bootstrap_group	Specifies whether to use the current server to bootstrap the group. This variable can be set on only one server and can be set on only one of the servers when the group is being bootstrapped or re-bootstrapped. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_components_stop_timeout	Specifies the timeout period for each component when the group is being shut down, in seconds. The default value is `2`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_compression_threshold	Specifies the threshold for the number of messages sent between group members. When the threshold is exceeded, the messages are compressed. The default value is `1000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_enforce_update_everywhere_checks	Specifies whether to enable or disable strict consistency checks for multi-primary updates at any time. The default value is `OFF`, which specifies to disable the checks. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_exit_state_action	Specifies the behavior of group replication when a server instance leaves the group due to an exception. The default value is `READ_ONLY`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_applier_threshold	Specifies the number of transactions waiting in the application queue that triggers flow control. The default value is `25000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_certifier_threshold	Specifies the number of transactions waiting in the certifier queue that triggers flow control. The default value is `25000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_mode	Specifies the mode for flow control. The default value is `QUOTA`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_force_members	Specifies the list of member addresses in the format of `host1:port1,host2:port2`. This variable is used to forcibly establish a new group. After this variable is set, members not specified in this variable will not receive new view messages and will be blocked (write operations are blocked). The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_name	Specifies the name of the group replication group to which the current server belongs. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_seeds	Specifies the list of seed member addresses in the format of `host1:port1,host2:port2`. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_gtid_assignment_block_size	Specifies the number of consecutive GTIDs to reserve for each member. The default value is `1000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ip_whitelist	Specifies the hosts (IP addresses or hostnames) that are allowed to connect to the group. The allowed addresses are called the allowlist. The default value is `AUTOMATIC`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_local_address	Specifies the network address for group replication members to provide to other members in the group for connection access. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_member_weight	Specifies the percentage weight for a group member, which affects the likelihood of the member being elected as the primary node during a failover (only relevant for groups in single-primary mode). In a group in single-primary mode, if the primary node leaves the group, the member with a higher weight is more likely to be elected as the primary node. The default value is `50`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_poll_spin_loops	Specifies the number of times the group replication communication thread waits for the communication engine's mutex to be released before it proceeds to wait for more network messages. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_complete_at	Specifies the strategy for applying cached transactions after the completion of state transfer during distributed recovery. The default value is `TRANSACTIONS_APPLIED`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_reconnect_interval	Specifies the interval between reconnection attempts when a new server cannot find a suitable donor for distributed recovery. The default value is `60` seconds. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_retry_count	Specifies the number of reconnection attempts when a new server cannot find a suitable donor for distributed recovery. The default value is `10`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_ca	Specifies the path of the file that contains the list of trusted SSL certificate authorities for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_capath	Specifies the directory path of the file that contains the certificates issued by the trusted SSL certificate authorities for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cert	Specifies the name of the SSL certificate file required to establish a secure connection for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cipher	Specifies the list of encryption algorithms allowed for SSL encryption. The available encryption algorithms depend on the SSL library version used when MySQL Server was compiled. Different SSL libraries support different encryption algorithms. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crl	Specifies the file name that contains the certificate revocation list. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crlpath	Specifies the directory path of the file that contains the certificate revocation list. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_key	Specifies the name of the SSL key file required to establish a secure connection for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_verify_server_cert	Specifies whether to verify the server common name in the donor certificate during distributed recovery. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_use_ssl	Specifies whether to use SSL for the connection channel during distributed recovery of group replication members. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_single_primary_mode	Specifies whether the group is in single-primary mode and whether to automatically select a server to handle read and write workloads. If this variable is set to `ON`, only one writable primary node exists, and other group members are all secondary nodes. If this variable is set to `OFF`, single-primary mode is disabled, and multi-primary mode is enabled. In multi-primary mode, all group members are usually writable primary nodes. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ssl_mode	Specifies the security state of SSL connections between group replication members. The default value is `DISABLED`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_start_on_boot	Specifies whether to start group replication when the server is started. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_transaction_size_limit	Specifies the maximum transaction size that can be received in group replication, in bytes. The default value is `150000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_unreachable_majority_timeout	Specifies the wait time before a group member leaves the group when the member is disconnected from the majority of members in the group due to a network partition. The default value is `0` seconds. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Session-level

Variable name	Description
ob_last_schema_version	Specifies the latest schema version used in the session.
old_alter_table	Specifies whether to enable the ALTER TABLE syntax and operation mode of the earlier version. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
debug	Specifies the debugging options. The default value is `d:t:i:o,/tmp/mysqld.trace`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.
debug_sync	Specifies the synchronization points when debugging. The default value is an empty string. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
is_result_accurate	When a query contains the `topk` hint, `is_result_accurate` indicates whether the result is correct.
long_query_time	Specifies the threshold for slow queries.

Variable name	Description
master_info_repository	Specifies whether to record the metadata in the InnoDB table mysql of the system database or as a file in the data directory. The default value is `FILE`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
table_definition_cache	Specifies the number of memory spaces for caching table definitions. The default value is `-1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable	Description
ob_capability_flag	The capabilities of the OBServer node, which are used for capability negotiation with the Proxy. This variable informs the Proxy of the features supported and not supported by the current OBServer node.
ob_proxy_partition_hit	Specifies whether to send SQL statements to the OBServer nodes hosting the primary partitions of the data.
ob_org_cluster_id	The `CLUSTER_ID` of the OceanBase cluster.

Variable	Description
have_profiling	Indicates whether performance analysis is supported. The default value is `NO`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.
profiling	Specifies whether to enable statement analysis. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried and set, but setting it does not result in an error or take effect.
profiling_history_size	The number of historical records for query performance information. The default value is `15`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried and set, but setting it does not result in an error or take effect.

Variable	Description
ob_enable_show_trace	Specifies whether to use trace logs.
tracefile_identifier	Specifies content to add to the log for easy filtering of row iteration trace logs.

Variable name	Description
pseudo_slave_mode	Specifies whether to switch the server to a pseudo slave mode. Default value is `OFF`. Note This variable is for backward compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. No error is returned when you set this variable, but the variable does not take effect.
pseudo_thread_id	The ID of the session thread. The default value is `2147483647`. Note The variable is used only to support compatibility with MySQL 5.7. You can query and set the variable. However, setting the variable does not trigger an error or take effect.
rbr_exec_mode	Specifies whether the session thread runs in the IDEMPOTENT or STRICT mode. Default value is

STRICT.

Note

This variable is supported only for compatibility with MySQL 5.7. You can query the value of the variable but cannot set it. If you set the variable, an error is not reported, but the setting does not take effect.

Time zones and dates

Variable Name	Description
timestamp	`TIMESTAMP` specifies the timestamp in seconds. The value of this variable affects the result of `SELECT NOW(6)`.
nls_language	Specifies the default language for database internationalization support, which is used for prompts, dates, month names, and the default values of `NLS_SORT` and `NLS_DATE_LANGUAGE`.

Transactions and transaction logs

Variable Name	Description
ob_proxy_set_trx_executed	Specifies whether a `START TRANSACTION Syntax` statement is sent to an OBServer node through an OBProxy.
ob_trace_info	Specifies a trace information field to be persisted to the redo logs.

Variable Name	Description
ob_table_access_policy	Specifies the default preferred storage format for the optimizer to generate base table plans.

Auto-increment columns

Variable	Description
last_insert_id	Returns the auto-increment field value of the last insertion in the current session.

Variable name	Description
group_replication_force_members	Specifies the list of member addresses in the format of `host1:port1,host2:port2`. This variable is used to forcibly establish a new group. After this variable is set, members not specified in this variable will not receive new view messages and will be blocked (from writing). The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_name	Specifies the name of the group replication group to which the current server belongs. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_gtid_assignment_block_size	Specifies the number of consecutive GTIDs to be reserved for each member. The default value is `1000000`. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ip_whitelist	Specifies the host (IP address or host name) that is allowed to connect to the group. The allowed address is called a white list address. The default value is `AUTOMATIC`. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_local_address	Specifies the network address for a group replication member to provide to other members in the group for connection access. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_ca	Specifies the path of the file that contains the list of trusted SSL certificate authorities for distributed recovery connections. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_capath	Specifies the directory path of the certificate issued by the trusted SSL certificate authorities for distributed recovery connections. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cert	Specifies the name of the SSL certificate file for establishing a secure connection required for distributed recovery. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cipher	Specifies the list of encryption algorithms that can be used for SSL encryption. The available encryption algorithms depend on the version of the SSL library used when MySQL Server was compiled. Different SSL libraries support different encryption algorithms. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crl	Specifies the name of the file that contains the certificate revocation list. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crlpath	Specifies the directory path of the certificate revocation list file. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_key	Specifies the name of the SSL key file for establishing a secure connection required for distributed recovery. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

This topic describes the system variables of OceanBase Database based on the functions of the system variables.

Global level

Variable	Description
validate_password_check_user_name	Specifies whether a user password can be the same as the username.
validate_password_length	Specifies the minimum length of a user password.
validate_password_mixed_case_count	Specifies the minimum number of uppercase and lowercase letters in a user password.
validate_password_number_count	Specifies the minimum number of digits in a user password.
validate_password_policy	Specifies the password check strategy.
validate_password_special_char_count	Specifies the minimum number of special characters in a user password.
ob_tcp_invited_nodes	Specifies the IP address list of a tenant, which serves as the IP address whitelist. The IP address list supports the percent sign (%), hyphen (-), and IP address. Multiple IP addresses are separated with commas (,). The IP address list supports IP address list matching, mask matching, and fuzzy matching.
default_password_lifetime	Specifies the password expiration period.
block_encryption_mode	Specifies the encryption algorithm used in the AES encryption and decryption functions.
sql_safe_updates	Specifies whether to enable the MySQL SQL security mode. The default value is `OFF`.
super_read_only	Specifies the read/write permissions of the database. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.

Variable name	Description
version_comment	Displays the version information of the OBServer node.
version	Displays the server version number.
ob_last_schema_version	Specifies the latest schema version used in the session.
ob_proxy_global_variables_version	Specifies the latest version of global variables that the OBServer node returns to the OBproxy.
ob_enable_transmission_checksum	Specifies whether to perform packet checksum verification between the obproxy and the OBServer node. This setting takes effect immediately.
ob_compatibility_control	Controls the behavior mode when compatibility conflicts occur between MySQL 5.7 and MySQL 8.0.
ob_compatibility_version	Specifies the OceanBase Database version that the product is compatible with when its behavior changes.
ob_security_version	Specifies the OceanBase Database version that the security feature is compatible with. The compatible version is specified when the tenant is created and cannot be modified after the tenant is created.
old_alter_table	Specifies whether to use the ALTER TABLE syntax and operation mode of the earlier version. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Variable name	Description
debug	Specifies the debug options. The default value is `d:t:i:o,/tmp/mysqld.trace`. Note This variable is supported only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
debug_sync	Specifies the synchronization points when Debug is enabled. The default value is an empty string. Note This variable is supported only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
ob_global_debug_sync	Specifies the synchronization points when Debug is enabled. This variable differs from `debug_sync` in that setting this variable affects all sessions.

Case sensitivity

Variable name	Description
lower_case_table_names	Specifies whether to use case-sensitive table names.

Variable name	Description
query_cache_size	Specifies the memory size allocated for storing the results of historical queries, which is the unused memory.
query_cache_type	Specifies the query cache type.
ob_query_timeout	Specifies the query timeout period.
is_result_accurate	When a query contains the `topk` hint, `is_result_accurate` indicates whether the result is accurate.
net_buffer_length	Specifies the maximum size of an SQL query that an OBServer node can accept.
read_only	Specifies whether the tenant is in read-only mode.
ob_read_consistency	Specifies the read consistency level.
ob_max_read_stale_time	Specifies the maximum latency threshold (in microseconds) for weak-consistency reads.
net_read_timeout	Specifies the number of seconds that a connection waits for other data to be read before it is interrupted.
net_write_timeout	Specifies the number of seconds that a connection waits for block writes before it is interrupted.
ob_enable_index_direct_select	Specifies whether to allow users to directly query index tables.
ob_enable_aggregation_pushdown	Specifies whether to allow aggregation operations to be pushed down.
ob_enable_jit	Specifies the JIT execution engine mode.
sql_throttle_network	Specifies the request queuing time. If the queuing time exceeds or equals this value, queries are not executed.
parallel_servers_target	Specifies the large query queuing conditions on each server.
cte_max_recursion_depth	Specifies the maximum recursion depth of common table expressions (CTEs). The server terminates any operation that exceeds this CTE value.
regexp_stack_limit	Specifies the maximum available memory size for the internal stack used in regular expression matching operations.
regexp_time_limit	Specifies the time limit for regular expression matching operations.
long_query_time	Specifies the threshold for slow queries.

Event Scheduler

Variable	Description
event_scheduler	Specifies whether the event scheduler is enabled and running on the server.

Variable	Description
ob_create_table_strict_mode	Specifies the strict mode for table creation.
ob_default_replica_num	Specifies the default number of replicas for each table in a cluster.
master_info_repository	Specifies whether to store replica metadata in an InnoDB table of the MySQL system database or as a file in the data directory. The default value is `FILE`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
replication_optimize_for_static_plugin_config	Specifies whether to enable shared locks to improve the performance of semi-synchronous replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
replication_sender_observe_commit_only	Specifies whether to enable restricted callbacks to improve the performance of semi-synchronous replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_semi_sync_slave_enabled	Specifies whether to enable semi-synchronous replication on the replica. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_semi_sync_slave_trace_level	Specifies the debugging trace level for semi-synchronous replication on the replica. The default value is `32`, which indicates the network wait level. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
rpl_stop_slave_timeout	Specifies the time to wait for more data or a heartbeat signal from the source before the STOP SLAVE operation times out, in seconds. The default value is `31536000`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_checkpoint_group	Specifies the maximum number of transactions that can be processed by multi-threaded replication before a checkpoint operation is called to update the progress status. The default value is `512`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_checkpoint_period	Specifies the maximum time allowed, in milliseconds, between the start of a checkpoint operation and the start of the next one to update the progress status of multi-threaded replication. The default value is `300`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_compressed_protocol	When both the source and the replica support compression, specifies whether to use the compression of the source or the replica. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_exec_mode	Specifies how the replication threads resolve conflicts and errors during replication. Setting this variable to `IDEMPOTENT` suppresses errors for duplicate and not-found keys. Setting this variable to `STRICT` does not suppress errors for duplicate and not-found keys. The default value is `STRICT`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_max_allowed_packet	Specifies the maximum size of data packets for the replication SQL and I/O threads, in bytes. The default value is `1073741824`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_net_timeout	Specifies the time to wait for more data or a heartbeat signal from the source before the replica considers the connection to be disconnected, aborts reading, and attempts to reconnect, in seconds. The default value is `60`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_parallel_type	Specifies the type of parallelism to use for executing replication transactions when multi-threaded replication is enabled. The default value is `DATABASE`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_parallel_workers	Specifies the number of threads to use for parallel execution of replication transactions. The default value is `0`, which disables parallel execution of replication transactions. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_pending_jobs_size_max	For multi-threaded replication, specifies the maximum length of the work queue for events that have not been applied, in bytes. The default value is `16777216`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_preserve_commit_order	For multi-threaded replication, specifies whether to commit transactions in the order of the relay logs. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_rows_search_algorithms	Specifies the algorithm that the replica uses to search for related rows. The default value is `TABLE_SCAN,INDEX_SCAN`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_sql_verify_checksum	Specifies whether to use the checksums read from the relay logs to verify data during replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_transaction_retries	Specifies the number of times the system automatically re-executes a transaction when the replication SQL thread fails due to a deadlock or the transaction execution time exceeds the value specified by the `innodb_lock_wait_timeout` variable. The default value is `10`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
slave_type_conversions	Specifies the type conversion mode on the replica when using row-based replication. The default value is empty, which specifies to prohibit type conversion between the source and the replica. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
sql_slave_skip_counter	Specifies the number of events to skip from the source for the replica. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. However, setting this variable does not take effect and does not generate an error.
skip_slave_start	Specifies whether to skip the startup of the replication thread when the replica server starts. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.
slave_load_tmpdir	Specifies the directory name for temporary files created by the replica. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.
slave_skip_errors	Specifies which errors to skip during replication. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related features are not supported. You can query this variable, but you cannot set it.

Variable name	Description
rpl_semi_sync_master_enabled	Specifies whether to enable semi-synchronous replication on the source. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_timeout	Specifies the time in milliseconds that the source waits for a replica to confirm the transaction after the transaction is committed. The default value is `10000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_trace_level	Specifies the debug trace level for semi-synchronous replication on the source. The default value is `32`, which indicates the network wait level. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_for_slave_count	Specifies the number of replica acknowledgments that each transaction must receive before the source continues. The default value is `1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_no_slave	Specifies whether to wait for the timeout period specified by the `rpl_semi_sync_master_timeout` variable when the number of replicas falls below the value set by the `rpl_semi_sync_master_wait_for_slave_count` variable. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
rpl_semi_sync_master_wait_point	Specifies the point in time at which the semi-synchronous source waits for replica acknowledgment of transaction reception before returning the status to the client that committed the transaction. The default value is `AFTER_SYNC`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Variable name	Description
recyclebin	Specifies whether to enable the recycle bin feature.
ob_enable_truncate_flashback	Specifies whether to enable flashback for table truncation.

Variable name	Description
ob_enable_plan_cache	Specifies whether to enable the plan cache.
ob_plan_cache_percentage	Specifies the percentage of memory available to the plan cache out of the total memory of the tenant.
ob_plan_cache_evict_high_percentage	Specifies the percentage of memory at which plan cache eviction is triggered, relative to the absolute maximum memory.
ob_plan_cache_evict_low_percentage	Specifies the percentage of memory at which plan cache eviction is stopped, relative to the absolute maximum memory.
ob_bnl_join_cache_size	Specifies the number of data records to cache for each batch in a Batch Nest Loop Join operation.
stored_program_cache	Specifies the number of cached stored procedures and functions. The default value is `256`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.
table_definition_cache	Specifies the number of memory spaces for caching table definitions. The default value is `-1`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Variable name	Description
interactive_timeout	Specifies the number of seconds that the server waits for activity before closing an interactive connection.
wait_timeout	Specifies the number of seconds that the server waits for activity before closing a non-interactive connection.
group_concat_max_len	Specifies the maximum length of the result of the `GROUP_CONCAT()` function.

Variable name	Description
innodb_change_buffering_debug	Specifies the debugging level for changing the InnoDB buffer. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_compress_debug	Specifies the debugging level for adjusting and controlling the compression behavior. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_disable_resize_buffer_pool_debug	Specifies whether to enable the adjustment of the InnoDB buffer pool size. The default value is `1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_fil_make_page_dirty_debug	Specifies the number of pages to dirty in the InnoDB buffer for debugging. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_limit_optimistic_insert_debug	Specifies the number of records on each B-tree page. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_merge_threshold_set_all_debug	Specifies the page full percentage of index pages. The default value is `50`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_saved_page_number_debug	Specifies the number of page numbers to save in the InnoDB buffer for debugging. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_trx_purge_view_update_only_debug	Specifies the debugging level for updating only the purge view during transaction cleanup. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_trx_rseg_n_slots_debug	Specifies the number of slots in the transaction rollback segment (transaction rollback segment). Each slot stores the rollback information of a transaction. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_stats_persistent	Specifies whether to persist the InnoDB index statistics to the disk.
innodb_force_recovery	Specifies the crash recovery mode for repairing the data of the damaged InnoDB storage engine. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_replication_delay	Specifies the delay of the replication threads on the replication server when the value of the `innodb_thread_concurrency` variable is reached, in milliseconds. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_large_prefix	Specifies whether to allow index key prefixes longer than 767 bytes (up to 3072 bytes) for InnoDB tables that use the DYNAMIC or COMPRESSED row format. The default value is `ON`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_sort_buffer_size	Specifies the size of the buffer for sorting operations. The default value is `1048576`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
default_tmp_storage_engine	Specifies the default temporary table storage engine. The default value is `InnoDB`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_tmpdir	Specifies the directory for storing temporary files of InnoDB. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
mecab_rc_file	Specifies the path of the MeCab configuration file. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_temp_data_file_path	Specifies the storage path for temporary data files of InnoDB. The default value is `ibtmp1:12M:autoextend`, which indicates that InnoDB will use a temporary data file named ibtmp1, with an initial size of 12 MB, and the file will automatically expand as needed to store additional temporary data. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_data_file_path	Specifies the storage path and filename for InnoDB data files, with the default value of `ibdata1:12M:autoextend`. This indicates that InnoDB will use a temporary data file named ibdata1, with an initial size of 12 MB, and the file will automatically expand as needed to store additional temporary data. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.
innodb_data_home_dir	Specifies the root directory for InnoDB data files. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable but cannot set it.

Variable	Description
ob_capability_flag	The capabilities of an OBServer node. This variable is used to negotiate capabilities with the proxy. It informs the proxy of the features supported by the current OBServer node.
ob_compatibility_mode	The compatibility mode of the tenant.
ob_route_policy	The routing strategy for selecting a data replica on an OBServer node.
performance_schema	Specifies whether to support queries for performance information. The default value is `OFF`. Note This variable is only for compatibility with MySQL 8.0. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
resource_manager_plan	The resource management plan. If you specify different plans, different CPU quotas are used to limit user activities in a resource group.
license	The type of the license.
ob_proxy_partition_hit	Specifies whether to send SQL statements to the OBServer node that hosts the primary partition where the data is located.
ob_org_cluster_id	The `CLUSTER_ID` of the OceanBase cluster.
server_uuid	The UUID of the OBServer node.
default_storage_engine	The default storage engine of the OBServer node.
slave_allow_batching	Specifies whether to enable batch updates for the replication thread. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Variable	Description
datadir	The local disk path for storing data.
plugin_dir	The path for storing plugin DLLs.
secure_file_priv	The path that can be accessed when importing or exporting to a file.
ob_enable_hash_group_by	Specifies whether to enable Hash Group by.

Variable	Description
delay_key_write	Specifies whether to delay the writing of index keys for MyISAM tables. The default value is `ON`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_buffer_size	Specifies the size of the key buffer for the MyISAM storage engine. The default value is `8388608`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_age_threshold	Specifies the threshold for degrading the hot sublists of the key cache to the warm sublists. A lower value means faster degradation. The default value is `300`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_block_size	Specifies the size of each block in the MyISAM key cache. The default value is `1024`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
key_cache_division_limit	Specifies the division limit for the MyISAM key cache. The default value is `100`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.
max_seeks_for_key	Specifies the maximum number of address operations performed in a MyISAM query. The default value is `18446744073709551615`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and no error is reported.

Temporary files

Variable	Description
max_tmp_tables	The maximum number of temporary tables that a user session can hold simultaneously. The default value is `32`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not trigger an error but also does not take effect.

Memory

Variable	Description
ob_sql_work_area_percentage	The percentage of tenant memory that is allocated for SQL execution.
ob_sql_audit_percentage	The maximum percentage of tenant memory that is allocated for SQL audit.
ob_reserved_meta_memory_percentage	The percentage of tenant memory that is reserved for storing meta-related structural information.
ob_temp_tablespace_size_percentage	The percentage of tenant memory that is allocated for temporary tablespaces.

System logs

Variable	Description
binlog_row_image	Specifies whether to record full-column logs.
ob_enable_show_trace	Specifies whether to use trace logs.
ob_log_level	The log level of the session. If not specified, the system log level is used.
tracefile_identifier	Specifies the content to be added to the log for filtering row iteration trace logs.
master_verify_checksum	Specifies whether to enable checksum verification. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not trigger an error but also does not take effect.

Variable name	Description
innodb_ft_enable_diag_print	Specifies whether to enable or disable diagnostic output for InnoDB full-text indexing. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_num_word_optimize	Specifies the minimum number of words to be processed during an OPTIMIZE TABLE operation. The default value is `2000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_result_cache_limit	Specifies the size of the result cache for InnoDB full-text indexing. The default value is `2000000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_server_stopword_table	Specifies the server stopword table for InnoDB full-text indexing. The default value is `NULL`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_optimize_fulltext_only	Specifies whether to perform an OPTIMIZE TABLE operation only on InnoDB tables that contain FULLTEXT indexes. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting it does not take effect and does not generate an error.
innodb_ft_cache_size	Specifies the size of the InnoDB full-text index cache. The default value is `8000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
innodb_ft_sort_pll_degree	Specifies the number of parallel threads for sorting full-text indexes. The default value is `2`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
innodb_ft_total_cache_size	Specifies the total size of the InnoDB full-text index cache. The default value is `640000000`, which is in bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.
ft_stopword_file	Specifies the path of the file that contains stop words to be excluded. The default value is `built-in`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query this variable, but you cannot set it.

Variable name	Description
runtime_filter_type	Specifies the type of runtime filter for a tenant.
runtime_filter_wait_time_ms	Specifies the maximum wait time for a runtime filter.
runtime_filter_max_in_num	Specifies the number of NDV (number of distinct values) for a runtime in filter.
runtime_bloom_filter_max_size	Specifies the maximum memory size of a runtime Bloom filter, in bytes.

Variable name	Description
avoid_temporal_upgrade	Specifies the behavior of upgrading time-sensitive data (such as dates and times). The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable, but the setting does not take effect and no error is reported.

Time zones and dates

Variable name	Description
time_zone	Specifies the time zone for the current tenant session. Valid values are in the offset format, such as `'+08:00'`, and the region format, such as `Asia/Shanghai`.
timestamp	`TIMESTAMP` is a timestamp in seconds. This variable affects the result of `select now(6)`.
system_time_zone	Specifies the system time zone of the server.
error_on_overlap_time	Specifies whether to return an error when the time zone overlaps occur.
nls_language	Specifies the default language for database internationalization support. This variable is used to specify the default values for prompts, dates, month names, `NLS_SORT`, and `NLS_DATE_LANGUAGE`.
nls_territory	Specifies the current region for database internationalization support. This variable is used in combination with `nls_language`.
nls_date_language	Specifies the default language for dates in database internationalization support.
nls_calendar	Specifies the calendar system used by the database.
ob_timestamp_service	Specifies the timestamp service to be used.

Variable name	Description
autocommit	Specifies whether to automatically commit a transaction.
tx_isolation	Specifies the transaction isolation level.
ob_proxy_set_trx_executed	Specifies whether to send the `START TRANSACTION Syntax` statement to the OBServer node through obproxy.
ob_early_lock_release	Specifies whether to enable the early lock release (ELR) feature for a transaction. Note This variable is deprecated in V2.2.30. The ELR feature is now controlled by the tenant-level configuration item `enable_early_lock_release`.
ob_trx_idle_timeout	Specifies the transaction idle timeout period, which is the time interval between the execution of two statements in a transaction that exceeds the timeout period.
transaction_isolation	Specifies the transaction isolation level.
transaction_read_only	Specifies whether to allow only read-only transactions.
ob_trx_lock_timeout	Specifies the timeout period for a transaction to wait for a lock.
tx_read_only	Specifies whether to set a transaction to read-only.
ob_trx_timeout	Specifies the transaction timeout period.
ob_trace_info	Specifies whether to pass trace information, which can be persisted to the redo log.

Variable name	Description
ob_enable_sql_audit	Specifies whether to enable the SQL audit feature for the current tenant.

Data types

Variable name	Description
nls_length_semantics	Specifies the length semantics for the CHAR and VARCHAR2 data types.
nls_nchar_conv_excp	Specifies whether to return an error when data is lost during conversion between the NCHAR and NVARCHAR2 data types and the CHAR and VARCHAR2 data types.
nls_numeric_characters	Specifies the characters used for decimal and thousand separators in string representations of numbers.
nls_currency	Specifies the local currency symbol for the `L` format element in the number format.
nls_iso_currency	Specifies the local currency symbol for the `C` format element in the number format.
nls_dual_currency	Specifies the local currency symbol for the `U` format element in the number format.
nls_date_format	Specifies the format for converting the date data type to a string and for implicitly converting a string to a date.
nls_timestamp_format	Specifies the format for converting the TIMESTAMP or TIMESTAMP_LTZ data types to a string and for implicitly converting a string to a TIMESTAMP or TIMESTAMP_LTZ data type.
nls_timestamp_tz_format	Specifies the format for converting the TIMESTAMP_TZ data type to a string and for implicitly converting a string to a TIMESTAMP_TZ data type.
explicit_defaults_for_timestamp	Specifies whether to enable non-standard behavior for the TIMESTAMP data type when handling default values and null values.
log_row_value_options	Specifies whether to enable partial updates for LOBs.
ob_default_lob_inrow_threshold	Specifies the default in-row storage threshold for LOB fields when a table is created.

Variable	Description
connect_timeout	Specifies the connection timeout period.
ob_pl_block_timeout	Specifies the maximum timeout period for PL.
cursor_sharing	Specifies whether to parameterize SQL statements.
have_profiling	Specifies whether performance analysis is supported. The default value is `NO`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query this variable, but cannot set it.
profiling	Specifies whether to enable the statement analysis feature. The default value is `0`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
profiling_history_size	Specifies the number of records to be saved for query performance information. The default value is `15`. Note This variable is supported only for MySQL 5.7 compatibility. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is returned.
innodb_strict_mode	Specifies the SQL check mode for specific syntaxes.
max_connections	Specifies the maximum number of connections for the tenant.
sql_mode	Specifies the SQL mode, which has a significant impact on operations such as data insertion.
sql_quote_show_create	Specifies whether to enable identifier quoting for `SHOW CREATE TABLE` and `SHOW CREATE DATABASE` statements.
ob_enable_rich_error_msg	Specifies whether to display information such as svr_ip, time, and trace_id when an SQL execution error occurs.
sql_throttle_current_priority	Specifies the throttling priority. Only requests from sessions where `sql_throttle_current_priority` is less than `sql_throttle_priority` will be throttled.
sql_throttle_priority	Specifies the throttling priority.
sql_throttle_rt	Specifies the response time (RT) value.
max_allowed_packet	Specifies the maximum size of network packets.
max_user_connections	Specifies the maximum number of connections that a single user can establish with an OBServer node. A value of `0` indicates no limit.
max_sp_recursion_depth	Specifies the maximum number of recursive calls to any specified stored procedure.
sql_select_limit	Specifies the maximum number of rows that a single SELECT query can return.
max_connections	Specifies the maximum number of connections for the tenant.
ob_enable_blk_nestedloop_join	Specifies whether to enable block nested loop join.
parallel_max_servers	Specifies the maximum number of threads in the parallel execution (PX) thread pool on each server.

Variable name	Description
metadata_locks_cache_size	Specifies the cache size for metadata locks. The default value is `1024` bytes. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.
metadata_locks_hash_instances	Specifies the number of instances for the metadata lock hash table. The default value is `8`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.

Variable name	Description
foreign_key_checks	Specifies whether to check foreign key constraints during DML or DDL operations.

Variable name	Description
optimizer_use_sql_plan_baselines	Controls whether the optimizer uses plan baselines.
optimizer_capture_sql_plan_baselines	Controls whether to automatically capture new plans to plan baselines.
parallel_degree_policy	Specifies the parallelism selection strategy.
parallel_degree_limit	Specifies the maximum degree of parallelism that the optimizer selects when the auto DOP strategy is used.
parallel_min_scan_time_threshold	Specifies the minimum estimated execution time for parallel processing of base table scans.
optimizer_dynamic_sampling	Controls the level of dynamic sampling.
optimizer_features_enable	Specifies the optimizer features of different OceanBase versions.
ob_enable_transformation	Specifies whether to enable the rewrite feature of the SQL optimizer.
ob_table_access_policy	Controls the optimizer to prefer specific storage formats when generating base table plans.

Auto-increment columns

Variable	Description
auto_increment_increment	Specifies the auto-increment step, which is only used when a MySQL client logs in.
auto_increment_offset	Specifies the starting value of the `AUTO_INCREMENT` column.
last_insert_id	Returns the last auto-increment field value inserted in the current session.
identity	`identity` and `last_insert_id` are synonyms. You can run `select @@identity` to query the value.
sql_auto_is_null	Specifies whether to retrieve the auto-increment column value of the last inserted row.
auto_increment_cache_size	Specifies the number of auto-increment values cached.
div_precision_increment	Specifies the increment of the precision of the result of a division operation based on the precision of the dividend. This is a MySQL-compatible feature.

Character sets and strings

Variable	Description
character_set_client	Specifies the character set for statements sent by the client.
character_set_connection	Specifies the character set for statements received by the server.
character_set_database	Specifies the character set for the default database.
character_set_results	Specifies the character set for converting results or error messages sent to the client.
character_set_server	Specifies the character set for the server.
character_set_system	Specifies the character set used by the server.
collation_connection	Specifies the character set and collation for the connection.
collation_database	Specifies the default character set and collation for creating databases.
collation_server	Specifies the default character set and collation for the server.
character_set_filesystem	Specifies the character set for the file system.
sql_warnings	Controls whether to generate an information string for single-line INSERT statements when an alert is triggered.
init_connect	Specifies the string executed by the server for each client connection, which consists of one or more SQL statements separated by semicolons.
nls_sort	Specifies the collation for the string value.
nls_comp	Specifies the comparison rule for the string value.
nls_characterset	Specifies the default character set for CHAR, VARCHAR2, CLOB, and other data types in the database.
nls_nchar_characterset	Specifies the default character set for NCHAR, NVARCHAR2, and NCLOB data types in the database.

Variable name	Description
group_replication_allow_local_disjoint_gtids_join	Specifies whether to allow a server to join the group if the server has local transactions that are not in the group. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_allow_local_lower_version_join	Specifies whether to allow a server to join the group if the server is running a MySQL Server version that is earlier than the version of other members in the group. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_auto_increment_increment	Specifies the auto-increment value step for each member in the group to ensure that the auto-increment values of the group members are ordered and non-overlapping in multi-primary mode. The default value is `7`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_bootstrap_group	Specifies whether to use the current server to bootstrap the group. This variable can be set on only one server and can be set on only one of the servers when the group is being bootstrapped or re-bootstrapped. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_components_stop_timeout	Specifies the timeout period for each component when the group is being shut down, in seconds. The default value is `2`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_compression_threshold	Specifies the threshold for the number of messages sent between group members. When the threshold is exceeded, the messages are compressed. The default value is `1000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_enforce_update_everywhere_checks	Specifies whether to enable or disable strict consistency checks for multi-primary updates at any time. The default value is `OFF`, which specifies to disable the checks. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_exit_state_action	Specifies the behavior of group replication when a server instance leaves the group due to an exception. The default value is `READ_ONLY`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_applier_threshold	Specifies the number of transactions waiting in the application queue that triggers flow control. The default value is `25000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_certifier_threshold	Specifies the number of transactions waiting in the certifier queue that triggers flow control. The default value is `25000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_flow_control_mode	Specifies the mode for flow control. The default value is `QUOTA`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_force_members	Specifies the list of member addresses in the format of `host1:port1,host2:port2`. This variable is used to forcibly establish a new group. After this variable is set, members not specified in this variable will not receive new view messages and will be blocked (write operations are blocked). The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_name	Specifies the name of the group replication group to which the current server belongs. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_seeds	Specifies the list of seed member addresses in the format of `host1:port1,host2:port2`. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_gtid_assignment_block_size	Specifies the number of consecutive GTIDs to reserve for each member. The default value is `1000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ip_whitelist	Specifies the hosts (IP addresses or hostnames) that are allowed to connect to the group. The allowed addresses are called the allowlist. The default value is `AUTOMATIC`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_local_address	Specifies the network address for group replication members to provide to other members in the group for connection access. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_member_weight	Specifies the percentage weight for a group member, which affects the likelihood of the member being elected as the primary node during a failover (only relevant for groups in single-primary mode). In a group in single-primary mode, if the primary node leaves the group, the member with a higher weight is more likely to be elected as the primary node. The default value is `50`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_poll_spin_loops	Specifies the number of times the group replication communication thread waits for the communication engine's mutex to be released before it proceeds to wait for more network messages. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_complete_at	Specifies the strategy for applying cached transactions after the completion of state transfer during distributed recovery. The default value is `TRANSACTIONS_APPLIED`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_reconnect_interval	Specifies the interval between reconnection attempts when a new server cannot find a suitable donor for distributed recovery. The default value is `60` seconds. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_retry_count	Specifies the number of reconnection attempts when a new server cannot find a suitable donor for distributed recovery. The default value is `10`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_ca	Specifies the path of the file that contains the list of trusted SSL certificate authorities for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_capath	Specifies the directory path of the file that contains the certificates issued by the trusted SSL certificate authorities for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cert	Specifies the name of the SSL certificate file required to establish a secure connection for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cipher	Specifies the list of encryption algorithms allowed for SSL encryption. The available encryption algorithms depend on the SSL library version used when MySQL Server was compiled. Different SSL libraries support different encryption algorithms. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crl	Specifies the file name that contains the certificate revocation list. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crlpath	Specifies the directory path of the file that contains the certificate revocation list. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_key	Specifies the name of the SSL key file required to establish a secure connection for distributed recovery. The default value is empty. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_verify_server_cert	Specifies whether to verify the server common name in the donor certificate during distributed recovery. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_use_ssl	Specifies whether to use SSL for the connection channel during distributed recovery of group replication members. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_single_primary_mode	Specifies whether the group is in single-primary mode and whether to automatically select a server to handle read and write workloads. If this variable is set to `ON`, only one writable primary node exists, and other group members are all secondary nodes. If this variable is set to `OFF`, single-primary mode is disabled, and multi-primary mode is enabled. In multi-primary mode, all group members are usually writable primary nodes. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ssl_mode	Specifies the security state of SSL connections between group replication members. The default value is `DISABLED`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_start_on_boot	Specifies whether to start group replication when the server is started. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_transaction_size_limit	Specifies the maximum transaction size that can be received in group replication, in bytes. The default value is `150000000`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_unreachable_majority_timeout	Specifies the wait time before a group member leaves the group when the member is disconnected from the majority of members in the group due to a network partition. The default value is `0` seconds. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Session-level

Variable name	Description
ob_last_schema_version	Specifies the latest schema version used in the session.
old_alter_table	Specifies whether to enable the ALTER TABLE syntax and operation mode of the earlier version. The default value is `OFF`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
debug	Specifies the debugging options. The default value is `d:t:i:o,/tmp/mysqld.trace`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.
debug_sync	Specifies the synchronization points when debugging. The default value is an empty string. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
is_result_accurate	When a query contains the `topk` hint, `is_result_accurate` indicates whether the result is correct.
long_query_time	Specifies the threshold for slow queries.

Variable name	Description
master_info_repository	Specifies whether to record the metadata in the InnoDB table mysql of the system database or as a file in the data directory. The default value is `FILE`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable name	Description
table_definition_cache	Specifies the number of memory spaces for caching table definitions. The default value is `-1`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, setting this variable does not trigger an error, but the setting does not take effect.

Variable	Description
ob_capability_flag	The capabilities of the OBServer node, which are used for capability negotiation with the Proxy. This variable informs the Proxy of the features supported and not supported by the current OBServer node.
ob_proxy_partition_hit	Specifies whether to send SQL statements to the OBServer nodes hosting the primary partitions of the data.
ob_org_cluster_id	The `CLUSTER_ID` of the OceanBase cluster.

Variable	Description
have_profiling	Indicates whether performance analysis is supported. The default value is `NO`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried but cannot be set.
profiling	Specifies whether to enable statement analysis. The default value is `0`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried and set, but setting it does not result in an error or take effect.
profiling_history_size	The number of historical records for query performance information. The default value is `15`. Note This variable is only for compatibility with MySQL 5.7. The related feature is not supported. It can be queried and set, but setting it does not result in an error or take effect.

Variable	Description
ob_enable_show_trace	Specifies whether to use trace logs.
tracefile_identifier	Specifies content to add to the log for easy filtering of row iteration trace logs.

Variable name	Description
pseudo_slave_mode	Specifies whether to switch the server to a pseudo slave mode. Default value is `OFF`. Note This variable is for backward compatibility with MySQL 5.7. The related features are not supported. You can query and set this variable. No error is returned when you set this variable, but the variable does not take effect.
pseudo_thread_id	The ID of the session thread. The default value is `2147483647`. Note The variable is used only to support compatibility with MySQL 5.7. You can query and set the variable. However, setting the variable does not trigger an error or take effect.
rbr_exec_mode	Specifies whether the session thread runs in the IDEMPOTENT or STRICT mode. Default value is

STRICT.

Note

Time zones and dates

Variable Name	Description
timestamp	`TIMESTAMP` specifies the timestamp in seconds. The value of this variable affects the result of `SELECT NOW(6)`.
nls_language	Specifies the default language for database internationalization support, which is used for prompts, dates, month names, and the default values of `NLS_SORT` and `NLS_DATE_LANGUAGE`.

Transactions and transaction logs

Variable Name	Description
ob_proxy_set_trx_executed	Specifies whether a `START TRANSACTION Syntax` statement is sent to an OBServer node through an OBProxy.
ob_trace_info	Specifies a trace information field to be persisted to the redo logs.

Variable Name	Description
ob_table_access_policy	Specifies the default preferred storage format for the optimizer to generate base table plans.

Auto-increment columns

Variable	Description
last_insert_id	Returns the auto-increment field value of the last insertion in the current session.

Variable name	Description
group_replication_force_members	Specifies the list of member addresses in the format of `host1:port1,host2:port2`. This variable is used to forcibly establish a new group. After this variable is set, members not specified in this variable will not receive new view messages and will be blocked (from writing). The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_group_name	Specifies the name of the group replication group to which the current server belongs. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_gtid_assignment_block_size	Specifies the number of consecutive GTIDs to be reserved for each member. The default value is `1000000`. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_ip_whitelist	Specifies the host (IP address or host name) that is allowed to connect to the group. The allowed address is called a white list address. The default value is `AUTOMATIC`. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_local_address	Specifies the network address for a group replication member to provide to other members in the group for connection access. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_ca	Specifies the path of the file that contains the list of trusted SSL certificate authorities for distributed recovery connections. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_capath	Specifies the directory path of the certificate issued by the trusted SSL certificate authorities for distributed recovery connections. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cert	Specifies the name of the SSL certificate file for establishing a secure connection required for distributed recovery. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_cipher	Specifies the list of encryption algorithms that can be used for SSL encryption. The available encryption algorithms depend on the version of the SSL library used when MySQL Server was compiled. Different SSL libraries support different encryption algorithms. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crl	Specifies the name of the file that contains the certificate revocation list. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_crlpath	Specifies the directory path of the certificate revocation list file. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.
group_replication_recovery_ssl_key	Specifies the name of the SSL key file for establishing a secure connection required for distributed recovery. The default value is empty. Note This variable is only supported for compatibility with MySQL 5.7. The related feature is not supported. You can query and set this variable. However, the setting does not take effect and no error is reported.

Customer Stories

Documentation

Overview of system variables

Global level

Security-related variables

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Variables related to version information

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Debug-related variables

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Case sensitivity

Read and write/Query-related

Event Scheduler

Replica-related variables

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Variables related to the source

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Variables related to the recycle bin

Cache-related

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Function-related

InnoDB storage engine-related variables

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Cluster-related variables

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System variables related to directory paths

System variables related to the MyISAM storage engine

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