This topic describes the system variables of OceanBase Database based on the functions of the system variables.
Global level
| Variable name |
Description |
| version_comment |
Displays the version of the OBServer node. |
| version |
Displays the server version number. |
| ob_last_schema_version |
Specifies the latest schema version used in the current 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 data packet checksum verification between the OBProxy and the OBServer node. This setting takes effect immediately after it is applied. |
| Variable name |
Description |
| debug_sync |
Specifies the synchronization point for debugging and is compatible with MySQL. |
| ob_global_debug_sync |
Specifies the synchronization point for debugging. Unlike debug_sync, setting this variable affects all sessions. |
| Variable |
Description |
| query_cache_size |
The size of memory allocated for storing the results of queries, which is the unused memory. |
| query_cache_type |
The type of the query cache. |
| ob_query_timeout |
The timeout period for a query. |
| is_result_accurate |
When a query contains the topk hint, the is_result_accurate variable indicates whether the result is accurate. |
| net_buffer_length |
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 |
The read consistency level. |
| ob_max_read_stale_time |
The maximum latency threshold (in microseconds) for weak-consistency reads. |
| net_read_timeout |
The number of seconds that an OBServer node waits for other data to be read before interrupting the read. |
| net_write_timeout |
The number of seconds that an OBServer node waits for block writes before interrupting the write. |
| 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 |
The request queuing time threshold. If the request queuing time is greater than or equal to this value, queries are not executed. |
| parallel_servers_target |
The conditions for queuing a large query on each server. |
| cte_max_recursion_depth |
The maximum recursion depth of a common table expression (CTE). The server terminates any operation that exceeds this CTE value. |
| regexp_stack_limit |
The maximum available memory for the internal stack of a regular expression matching operation. |
| regexp_time_limit |
The time limit for a regular expression matching operation. |
Event Scheduler
| Variable |
Description |
| event_scheduler |
Specifies whether to enable the event scheduler. |
Foreign keys
| Variable |
Description |
| foreign_key_checks |
Specifies whether to check foreign key constraints during DML or DDL operations. |
Replicas
Recycle bin
Caching
Functions
| Variable |
Description |
| interactive_timeout |
Specifies the number of seconds the server waits for activity before closing an interactive connection. |
| wait_timeout |
Specifies the number of seconds 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. |
Cluster
| Variable |
Description |
| ob_capability_flag |
The capabilities of the OBServer node, which are used to negotiate capabilities with the Proxy. This variable informs the Proxy of the features supported and not supported by the current OBServer node. |
| ob_compatibility_mode |
Specifies the compatibility mode of the tenant. |
| ob_route_policy |
Specifies the routing strategy for selecting data replicas on OBServer nodes. |
| performance_schema |
Specifies whether to support performance information queries. 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, but the setting does not take effect and no error is returned.
|
| resource_manager_plan |
Activates a resource management plan. Different plans use different CPU quotas to limit user activities in a resource group. |
| license |
Specifies the license type. |
| ob_proxy_partition_hit |
Specifies whether to send SQL statement requests to the OBServer node that hosts the primary partition of the data. |
| ob_org_cluster_id |
Specifies the CLUSTER_ID of the OceanBase cluster. |
| server_uuid |
Specifies the UUID of the OBServer node. |
| default_storage_engine |
Specifies the default storage engine of the OBServer node. |
Directories
Memory
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 for the session. If not specified, the system log level is used. |
| tracefile_identifier |
Specifies the content to add to the log for easier filtering of row iteration trace logs. |
| Variable |
Description |
| time_zone |
Specifies the time zone for the current tenant session. Valid values: '+08:00' (offset) and Asia/Shanghai (region). |
| timestamp |
A timestamp in seconds. The value of 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 a time zone overlap occurs. |
| nls_language |
Specifies the default language for database internationalization. This variable affects the default values of prompts, dates, month names, NLS_SORT, and NLS_DATE_LANGUAGE. |
| nls_territory |
Specifies the current region for database internationalization. This variable is used in combination with nls_language. |
| nls_date_language |
Specifies the default language for dates in database internationalization. |
| nls_calendar |
Specifies the calendar system used in the database. |
| ob_timestamp_service |
Specifies the timestamp service to be used. |
| Variable name |
Description |
| autocommit |
Specifies whether to automatically commit transactions. |
| 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 transactions.
Note
This variable is deprecated starting from 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. A transaction times out if the execution interval between two statements exceeds this 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 waiting for a lock. |
| tx_read_only |
Specifies whether the transaction is a read-only transaction. |
| 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 CHAR and VARCHAR2 types. |
| nls_nchar_conv_excp |
Specifies whether to report an error when data is lost during conversion between NCHAR/NVARCHAR2 and CHAR/VARCHAR2. |
| nls_numeric_characters |
Specifies the characters used as decimal and thousand separators in string representations of numbers. |
| nls_currency |
Specifies the local currency symbol for the number format element L. |
| nls_iso_currency |
Specifies the local currency symbol for the number format element C. |
| nls_dual_currency |
Specifies the local currency symbol for the number format element U. |
| nls_date_format |
Specifies the format for converting the date 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 type to a string and for implicitly converting a string to a TIMESTAMP or TIMESTAMP_LTZ. |
| nls_timestamp_tz_format |
Specifies the format for converting the TIMESTAMP_TZ type to a string and for implicitly converting a string to a TIMESTAMP_TZ. |
| explicit_defaults_for_timestamp |
Specifies whether to enable non-standard behavior for the TIMESTAMP data type when handling default values and null values. |
| ob_default_lob_inrow_threshold |
Specifies the default in-row storage threshold for LOB fields when creating a table. |
| 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. |
| 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. Setting this to 0 indicates no limit. |
| max_sp_recursion_depth |
Specifies the maximum level of recursion for 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 allow block nested loop joins. |
| parallel_max_servers |
Specifies the maximum number of threads in the parallel execution (PX) thread pool on each server. |
Auto-increment columns
| Variable |
Description |
| auto_increment_increment |
Specifies the auto-increment step size. This variable is applicable only to MySQL clients. |
| auto_increment_offset |
Specifies the starting value for the AUTO_INCREMENT column. |
| last_insert_id |
Returns the last auto-increment field value inserted in the current session. |
| identity |
The identity variable is a synonym for the last_insert_id variable. You can execute the select @@identity statement to query it. |
| 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 cached auto-increment values. |
| 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
Session level
| Variable name |
Description |
| ob_last_schema_version |
The schema version used in the latest operation in the session. |
| Variable name |
Description |
| is_result_accurate |
When a query contains the topk hint, the is_result_accurate variable indicates whether the result is accurate. |
| Variable name |
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 by the current OBServer node. |
| ob_proxy_partition_hit |
Specifies whether to send SQL statements to the OBServer node hosting the primary partition of the data. |
| ob_org_cluster_id |
The CLUSTER_ID of the OceanBase cluster. |
Time zones and dates
| Variable name |
Description |
| timestamp |
TIMESTAMP indicates the timestamp in seconds. This variable affects the result of the select now(6) statement. |
| nls_language |
This variable indicates 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 |
This variable specifies whether to send the START TRANSACTION Syntax statement to the OBServer through obproxy. |
| ob_trace_info |
This variable is used to pass trace information, which can be persisted to the REDO log. |
Auto-increment columns
| Variable name |
Description |
| last_insert_id |
This variable returns the value of the last auto-increment column in the current session. |
