This topic lists all the system variables of OceanBase Database based on the functions of the system variables.
Global level
| Variable name |
Description |
| debug_sync |
Specifies the synchronization point during Debug mode, and is compatible with MySQL. |
| ob_global_debug_sync |
Specifies the synchronization point during Debug mode. It differs from debug_sync in that setting this variable affects all sessions. |
| Variable name |
Description |
| query_cache_size |
Specifies the memory allocated for storing the results of 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 to wait for other data to be received before interrupting the read. |
| net_write_timeout |
Specifies the number of seconds to wait 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 |
Specifies the request queuing time. If the queuing time exceeds this value, queries will not be executed. |
| parallel_servers_target |
Specifies the conditions for queuing large queries on each server. |
| cte_max_recursion_depth |
Specifies the maximum recursion depth for common table expressions (CTEs). The server will terminate any operations exceeding this CTE value. |
| regexp_stack_limit |
Specifies the maximum amount of available memory for the internal stack used in regular expression matching. |
| regexp_time_limit |
Specifies the time limit for regular expression matching operations. |
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
Caches
Functions
| Variable |
Description |
| interactive_timeout |
The number of seconds the server waits for activity on an interactive connection before closing the connection. |
| wait_timeout |
The number of seconds the server waits for activity on a non-interactive connection before closing the connection. |
| group_concat_max_len |
The maximum length of the result of the GROUP_CONCAT() function. |
Cluster
| Variable |
Description |
| ob_capability_flag |
The capabilities that an OBServer node provides for connection with a Proxy. This variable is used for capability negotiation with a Proxy to inform the Proxy of the features supported and not supported by the current OBServer node. |
| ob_compatibility_mode |
The compatibility mode of the tenant. |
| ob_route_policy |
The routing strategy for selecting data replicas on an OBServer node. |
| 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. However, the setting does not take effect and no error is reported.
|
| resource_manager_plan |
The resource management plan to be activated. Different plans use different CPU quotas 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 data partition. |
| 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. |
| 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 current session. If not specified, the system log level is used. |
| tracefile_identifier |
The content to be added to the log for easy filtering of row iteration trace logs. |
| Variable |
Description |
| time_zone |
Specifies the time zone for the current tenant session. Valid values are in the +08:00 offset format and the Asia/Shanghai region format. |
| timestamp |
A TIMESTAMP is 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 ambiguity occurs in daylight saving time overlap zones. |
| nls_language |
Specifies the default language for database internationalization, which is used for prompts, dates, month names, and the default values of NLS_SORT and NLS_DATE_LANGUAGE. |
| nls_territory |
Specifies the current region for database internationalization, which 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 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 idle timeout period for a transaction. A transaction times out when the time interval between two statements exceeds this value. |
| transaction_isolation |
Specifies the transaction isolation level. |
| transaction_read_only |
Specifies whether to allow only read-only transactions. |
| ob_trx_lock_timeout |
Specifies the lock wait timeout period for a transaction. |
| 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 return an error when data is lost during conversion between NCHAR and CHAR or NVARCHAR2 and VARCHAR2. |
| nls_numeric_characters |
Specifies the characters used as the decimal separator and the thousand separator 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 the date type. |
| nls_timestamp_format |
Specifies the format for converting the TIMESTAMP or LTZ subtypes to a string and for implicitly converting a string to the TIMESTAMP or LTZ subtypes. |
| nls_timestamp_tz_format |
Specifies the format for converting the TIMESTAMP TZ type to a string and for implicitly converting a string to the TIMESTAMP TZ 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 use partial updates for LOBs. |
| ob_default_lob_inrow_threshold |
Specifies the default in-row storage threshold for LOB columns 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 perform parameterization when processing SQL statements. |
| innodb_strict_mode |
Specifies the SQL check mode for specific syntaxes. |
| max_connections |
Specifies the maximum number of connections for the entire tenant. |
| sql_mode |
Specifies the SQL mode, which has a significant impact on behaviors such as inserting data. |
| sql_quote_show_create |
Specifies whether to enable identifier quoting for the 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 error occurs during SQL execution. |
| 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 can be established from a single user to an OBServer node. If set to 0, the connection number is not limited. |
| 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 entire 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. |
Auto-increment columns
| Variable |
Description |
| auto_increment_increment |
Specifies the auto-increment step size, which applies only to MySQL clients. |
| auto_increment_offset |
Specifies the starting value for the AUTO_INCREMENT column. |
| last_insert_id |
Returns the value of the auto-increment field for the last inserted row in the current session. |
| identity |
identity is a synonym for the variable last_insert_id. You can use select @@identity to query it. |
| sql_auto_is_null |
Controls 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 |
| 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 nodes where the primary partitions of the requested data are located. |
| ob_org_cluster_id |
The CLUSTER_ID of the OceanBase cluster. |
Time zones and dates
| Variable name |
Description |
| timestamp |
TIMESTAMP is a timestamp, in seconds. 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 to send the START TRANSACTION syntax to the OBServer through obproxy. |
| ob_trace_info |
Specifies whether to pass trace information through. This information can be persisted to the redo log. |
Auto-increment columns
| Variable name |
Description |
| last_insert_id |
Returns the value of the auto-increment column inserted in the last operation in the current session. |
