This section describes the settings and value ranges of cluster transaction parameters.
transaction_isolation
Parameter description: Specifies the isolation level of the current transaction.
Type: USERSET
Value range:
- READ COMMITTED: Only committed data is read. This is the default.
- READ UNCOMMITTED: GaussDB(DWS) does not support READ UNCOMMITTED. If READ UNCOMMITTED is set, READ COMMITTED is executed instead.
- REPEATABLE READ: Only the data committed before transaction start is read. Uncommitted data or data committed in other concurrent transactions cannot be read.
- SERIALIZABLE: GaussDB(DWS) does not support SERIALIZABLE. If SERIALIZABLE is set, REPEATABLE READ is executed instead.
Default value: READ COMMITTED
transaction_read_only
Parameter description: Specifies that the current transaction is a read-only transaction.
Type: USERSET
Value range: Boolean
- on indicates that the current transaction is a read-only transaction.
- off indicates that the current transaction can be a read/write transaction.
Default value: off for CNs and on for DNs
xc_maintenance_mode
Parameter description: Specifies whether the system is in maintenance mode.
Type: SUSET
Value range: Boolean
- on indicates that maintenance mode is enabled.
- off indicates that the maintenance mode is disabled.
Default value: off
Enable the maintenance mode with caution to avoid cluster data inconsistencies.
allow_concurrent_tuple_update
Parameter description: Specifies whether to allow concurrent update.
Type: USERSET
Value range: Boolean
- on indicates it is enabled.
- off indicates it is disabled.
Default value: on
gtm_backup_barrier
Parameter description: Specifies whether to create a restoration point for the GTM starting point.
Type: SUSET
Value range: Boolean
- on indicates that a restoration point will be created for the GTM starting point.
- off indicates that a restoration point will not be created for the GTM starting point.
Default value: off
gtm_conn_check_interval
Parameter description: Sets the CN to check whether the connection between the local thread and the primary GTM is normal.
Parameter type: SIGHUP
Value range: an integer ranging from 0 to INT_MAX/1000. The unit is second.
Default value: 10s
transaction_deferrable
Parameter description: Specifies whether to delay the execution of a read-only serial transaction without incurring an execution failure. Assume this parameter is set to on. When the server detects that the tuples read by a read-only transaction are being modified by other transactions, it delays the execution of the read-only transaction until the other transactions finish modifying the tuples. Currently, this parameter is not used in GaussDB(DWS). Similar to this parameter, the default_transaction_deferrable parameter is used to specify whether to allow delayed execution of a transaction.
Type: USERSET
Value range: Boolean
- on indicates that the execution of a read-only serial transaction can be delayed.
- off indicates that the execution of a read-only serial transaction cannot be delayed.
Default value: off
enforce_two_phase_commit
Parameter description: This parameter is reserved for compatibility with earlier versions. This parameter is invalid in the current version.
enable_show_any_tuples
Parameter description: This parameter is available only in a read-only transaction and is used for analysis. When this parameter is set to on/true, all versions of tuples in the table are displayed.
Type: USERSET
Value range: Boolean
- on/true indicates that all versions of tuples in the table are displayed.
- off/false indicates that no versions of tuples in the table are displayed.
Default value: off
gtm_connect_retries
Parameter description: Specifies the number of GTM reconnection attempts.
Type: SIGHUP
Value range: an integer ranging from 1 to 2147483647.
Default value: 30
enable_redistribute
Parameter description: Specifies whether unmatched nodes are redistributed.
Type: SUSET
Value range: Boolean
- on indicates that unmatched nodes are redistributed.
- off indicates that unmatched nodes are not redistributed.
Default value: off