This topic lists the system variables of OceanBase Database in detail based on their intended use.
Global variables
Security variables
Version variables
Debugging variables
| Variable |
Description |
| debug_sync |
The synchronization point during debugging, which is compatible with MySQL. |
| ob_global_debug_sync |
The synchronization point during debugging. Unlike debug_sync, this variable takes effect on all sessions. |
Case sensitivity variables
| Variable |
Description |
| lower_case_table_names |
Specifies whether object names are case-sensitive for storage comparison. |
Read/Write and query variables
Scheduler variables
| Variable |
Description |
| event_scheduler |
Specifies whether the event scheduler is enabled and running on the OBServer node. |
FOREIGN KEY constraint variables
| Variable |
Description |
| foreign_key_checks |
Specifies whether to enable FOREIGN KEY constraint check for DML or DDL statements. |
Replica variables
Recycle bin variables
Cache variables
Function variables
| Variable |
Description |
| interactive_timeout |
The number of seconds that the OBServer node waits for an interactive idle connection to become active before closing it. |
| wait_timeout |
The number of seconds that the OBServer node waits for a non-interactive idle connection to become active before closing it. |
| group_concat_max_len |
The maximum length of the result of the GROUP_CONCAT() function. |
Cluster variables
| Variable |
Description |
| ob_capability_flag |
The capabilities that the OBServer node can provide. It is used to inform ODP of the features supported and features not supported by the OBServer node during capability negotiation between the OBServer node and ODP. |
| ob_compatibility_mode |
The compatibility mode of a tenant. |
| ob_route_policy |
The routing strategy for internal retries between ODP or the Java client and the OBServer node. |
| performance_schema |
Declares to the client whether performance queries are supported. |
| resource_manager_plan |
Activates a resource management plan. The CPU quota for limiting the user activities in a resource group varies based on the resource management plan. |
| license |
The license type. |
| ob_proxy_partition_hit |
Specifies whether to enable ODP to send the data requested by SQL statements to the OBServer node where the primary partition of the data is located. |
| ob_org_cluster_id |
The CLUSTER_ID of an OceanBase cluster. |
| server_uuid |
The UUID of the OBServer node. |
| default_storage_engine |
The default storage engine of an OBServer node. |
Directory variables
Memory variables
System log variables
| Variable |
Description |
| binlog_row_image |
Specifies whether to record full column logs. |
| ob_enable_show_trace |
Specifies whether to enable trace logs. |
| ob_log_level |
The level of session logs. If this variable is not specified, the system log level is used. |
| tracefile_identifier |
The custom identifier that becomes part of the log so that a row iteration trace log can be identified with ease. |
Runtime filter variables
Time zone and date variables
| Variable |
Description |
| time_zone |
The session time zone of the current tenant. The value can be an offset, such as '+08:00', or a geographical location, such as Asia/Shanghai. |
| timestamp |
The timestamp in seconds. This variable affects the result of SELECT NOW(6). |
| system_time_zone |
The system time zone of the server. |
| error_on_overlap_time |
Specifies whether to report an error in the case of an ambiguous overlap timestamp. |
| nls_language |
The default language of prompt messages, date, month, and the default values of nls_sort and nls_date_language. |
| nls_territory |
The current territory, which is used in combination with nls_language. |
| nls_date_language |
The default date language. |
| nls_calendar |
The calendar system used by the database. |
| ob_timestamp_service |
The timestamp service. |
Transaction and transaction log variables
| Variable |
Description |
| autocommit |
Specifies whether to automatically commit transactions. |
| tx_isolation |
The isolation level of transactions. |
| ob_proxy_set_trx_executed |
Specifies whether to send START TRANSACTION Syntax to OBServer through ODP. |
| ob_early_lock_release |
Specifies whether to enable the early lock release (ELR) feature for transactions. |
| ob_trx_idle_timeout |
The idle timeout period in which no transactions are executed. A timeout occurs if the execution interval between two consecutive statements exceeds the value of this variable. |
| transaction_isolation |
The isolation level of transactions. |
| transaction_read_only |
Specifies whether to enable just read-only transactions. |
| ob_trx_lock_timeout |
The lock wait timeout period for transactions. |
| tx_read_only |
Specifies whether the transaction is read-only. |
| ob_trx_timeout |
The transaction timeout period. |
| ob_trace_info |
Trace information to be transparently transferred, which can be stored in REDO logs. |
Audit variables
| Variable |
Description |
| ob_enable_sql_audit |
Specifies whether to enable SQL audit for the current tenant. |
Data type variables
| Variable |
Description |
| nls_length_semantics |
The length semantics of the CHAR and VARCHAR2 data types. |
| nls_nchar_conv_excp |
Specifies whether to report an error when data is lost during the conversion between NCHAR/NVARCHAR2 and CHAR/VARCHAR2. |
| nls_numeric_characters |
The decimal and thousands separators used in a string during the conversion between a number and a string. |
| nls_currency |
The local currency symbol for the L number format element. |
| nls_iso_currency |
The local currency symbol for the C number format element. |
| nls_dual_currency |
The local currency symbol for the U number format element. |
| nls_date_format |
The format of converting a date to a string and the format of implicitly converting a string to a date. |
| nls_timestamp_format |
The format to use when you convert a timestamp or LTZ timestamp to a string, or when you implicitly convert a string to a timestamp or LTZ timestamp. |
| nls_timestamp_tz_format |
The format to use when you convert a timestamp or TZ timestamp to a string, or when you implicitly convert a string to a timestamp or TZ timestamp. |
| explicit_defaults_for_timestamp |
Specifies whether to enable non-standard behaviors for processing default values and NULL values in TIMESTAMP columns. |
| log_row_value_options |
Specifies whether the LOB fields use partial updates. |
| ob_default_lob_inrow_threshold |
The default INROW storage threshold for LOB fields in a table. |
SQL/PL variables
Optimizer variables
Auto-increment column variables
| Variable |
Description |
| auto_increment_increment |
The auto-increment step size. It is used only for MySQL client logon. |
| auto_increment_offset |
The start value of an auto-increment column. |
| last_insert_id |
The last inserted auto-increment value in the current session. |
| identity |
The identity variable is synonymous with the last_insert_id variable and can be queried by using select @@identity. |
| sql_auto_is_null |
Specifies whether to obtain the auto-increment column value of the last inserted row. |
| auto_increment_cache_size |
The number of cached auto-increment values. |
| div_precision_increment |
The number of digits by which to increase the scale of the result of a division operation based on the scale of the dividend. This variable is for compatibility with MySQL. |
Character set and string variables
| Variable |
Description |
| character_set_client |
The character set in which the statements are sent by the client. |
| character_set_connection |
The character set to which the received statements are converted. |
| character_set_database |
The character set of the default database. |
| character_set_results |
The character set to which the server converts the result sets or error messages before sending them to the client. |
| character_set_server |
The character set of the server. |
| character_set_system |
The character set of the system. |
| collation_connection |
The character set and collation for the connection. |
| collation_database |
The default character set and collation of the database. |
| collation_server |
The default character set and collation for the server. |
| character_set_filesystem |
The character set of the file system. |
| sql_warnings |
Specifies whether to generate an information string for single-row INSERT statements when warnings occur. |
| init_connect |
The character string that the server executes for each connected client. The string consists of one or more SQL statements which are separated by semicolons (;). |
| nls_sort |
The string value sorting rule. |
| nls_comp |
The string value comparison rule. |
| nls_characterset |
Allows you to view the default character set of the data types such as CHAR, VARCHAR2, and CLOB in the database. |
| nls_nchar_characterset |
The default character set of the database, which is used for data types such as NCHAR, NVARCHAR2, and NCLOB. |
Session-level variables
Version variables
Read/Write and query variables
| Variable |
Description |
| is_result_accurate |
Specifies whether the query result is correct when a query carries a topk hint. |
Cluster variables
| Variable |
Description |
| ob_capability_flag |
The capabilities that the OBServer node can provide. It is used to inform ODP of the features supported and features not supported by the OBServer node during capability negotiation between the OBServer node and ODP. |
| ob_proxy_partition_hit |
Specifies whether to enable ODP to send the data requested by SQL statements to the OBServer node where the primary partition of the data is located. |
| ob_org_cluster_id |
The CLUSTER_ID of an OceanBase cluster. |
System log variables
| Variable |
Description |
| ob_enable_show_trace |
Specifies whether to enable trace logs. |
| tracefile_identifier |
The custom identifier that becomes part of the log so that a row iteration trace log can be identified with ease. |
Time zone and date variables
| Variable |
Description |
| timestamp |
The timestamp in seconds. This variable affects the result of SELECT NOW(6). |
| nls_language |
The default language of prompt messages, date, month, and the default values of nls_sort and nls_date_language. |
Transaction and transaction log variables
| Variable |
Description |
| ob_proxy_set_trx_executed |
Specifies whether to send START TRANSACTION Syntax to OBServer through ODP. |
| ob_trace_info |
Trace information to be transparently transferred, which can be stored in REDO logs. |
Auto-increment column variables
| Variable |
Description |
| last_insert_id |
The last inserted auto-increment value in the current session. |
