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.
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
idle_in_transaction_timeout
Parameter description: duration during which a transaction is allowed to be in the idle state. When a transaction is in the idle state for a period specified by this parameter, the transaction is terminated. This function takes effect only for client connections that are directly connected to CNs and does not take effect for direct DNs or internal connections. This parameter is supported only by clusters of version 8.2.1.100 or later.
Type: USERSET
Value range: 0 to 86400, in second. Value 0 indicates that this feature is disabled.
Default value: 0