Sending Server

max_wal_senders

Parameter description: Specifies the maximum number of concurrent connections of the Xlog sender. The value must be smaller than that of max_connections.

The prerequisite for setting max_wal_senders is as follows: wal_level must be set to archive, hot_standby, or logical to allow the connection to the standby node.

Parameter type: integer.

Unit: none

Value range: 0 to 1024. The recommended value range is 8 to 100.

Default value: 20

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion:

• This parameter can be set to 0 only when a single DN is used and there is no primary/standby instance.
• When HA replication, backup and restoration, and logical decoding are used, you are advised to set this parameter to: Number of current standby nodes + Number of backup connections + Number of required logical replication connections.

Risks and impacts of improper settings: If this parameter is set to a value less than the recommended value range, these functions may be unavailable or abnormal.

wal_keep_segments

Parameter description: Specifies the minimum number of Xlog files that can be retained in the pg_xlog directory. The standby node obtains the Xlogs from the primary node to perform streaming replication.

Parameter type: integer.

Unit: none

Value range: 2 to 2147483647

Default value: 128

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion:

• During WAL archiving or recovery from a checkpoint on the server, the system may retain more log files than the number specified by wal_keep_segments.
• If the HA system uses asynchronous transmission, increase the value of wal_keep_segments when data greater than 4 GB is continuously imported in COPY mode. Take T6000 board as an example. If the data to be imported reaches 50 GB, you are advised to set this parameter to 1000. You can dynamically restore the setting of this parameter after data import is complete and the log synchronization is normal.
• If the synchronous_commit level is lower than LOCAL_FLUSH, you are advised to set this parameter to 1000 when rebuilding the standby node to prevent rebuilding failures caused by primary node log recycling during the rebuilding.

Risks and impacts of improper settings: If the value is too large, the pg_xlog folder may occupy too much disk space. If the value is too small, the transaction log may have been overwritten by a new one before requested by the standby node. As a result, the request fails and the connection between the primary and standby nodes is terminated.

wal_sender_timeout

Parameter description: Specifies the maximum duration that the node waits for the receiver to receive transaction logs. This parameter can be set at the PDB level.

• If the data volume on the primary node is huge, the value of this parameter must be increased for rebuilding. For example, if the data volume on the primary node reaches 500 GB, you are advised to set this parameter to 600s.
• This parameter cannot be set to a value larger than the value of wal_receiver_timeout or the timeout parameter for database rebuilding.

Parameter type: integer.

Unit: millisecond

Value range: 0 to 2147483647

Default value: 6000. In the PDB scenario, if this parameter is not set, the global setting is inherited.

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: If the value is too small, the system is more sensitive to network fluctuation and intermittent disconnection. As a result, the connection between the primary and standby nodes may be abnormal. If the value is too large, the response to exceptions is slower.

max_replication_slots

Parameter description: Specifies the maximum number of log replication slots on the primary node.

Parameter type: integer.

Unit: none

Value range: 0 to 1024. The recommended value range is 8 to 100.

Default value: 20

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion:

When HA replication, backup and restoration, and logical decoding are used, you are advised to set this parameter to a value by referring to the following formula: Number of current physical streaming replication slots + Number of backup slots + Number of required logical replication slots. If the actual value is smaller than the recommended value, these functions may be unavailable or abnormal.

• Physical streaming replication slots provide an automatic method to ensure that Xlogs are not removed from a primary node before they are received by all the standby nodes. Therefore, physical streaming replication slots are used to support primary/standby HA. The number of physical streaming replication slots required by a database is equal to the ratio of the number of standby nodes to that of the primary node. For example, if an HA database has one primary node and one standby node, the number of required physical streaming replication slots will be one. If an HA database has one primary node and three standby nodes, the number of required physical streaming replication slots will be three.
• Backup slot records replication information during backup execution. Full backup and incremental backup correspond to two independent backup slots.
• Plan the number of logical replication slots as follows:
  • A logical replication slot can carry changes of only one database for decoding. If multiple databases are involved, create multiple logical replication slots.
  • If logical replication is needed by multiple target databases, create multiple logical replication slots in the source database. Each logical replication slot corresponds to one logical replication link.
  • A maximum of 20 logical replication slots can be enabled for decoding on the same instance.

Risks and impacts of improper settings: If the value is too small, the standby node cannot be connected, or logical decoding and backup archiving cannot be enabled. If the value is too large, the performance will be affected.

enable_slot_log

Parameter description: Specifies whether to enable primary/standby synchronization for replication slots. Only logical replication slots, archive slots, and backup slots are involved. This parameter can be set at the PDB level.

Parameter type: Boolean.

Unit: none

Value range:

• on: Primary/standby synchronization is enabled for replication slots.
• off: Primary/standby synchronization is disabled for replication slots.

Default value: on. In the PDB scenario, if this parameter is not set, the global setting is inherited.

Setting method: This is a USERSET parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Enable the function of creating archive/backup slots on the primary node and disable the function of creating archive/backup slots on the standby node.

Risks and impacts of improper settings: Functions (except replication and synchronization between the primary and standby nodes) such as backup, archiving, and building, will be affected.

enable_wal_shipping_compression

Parameter description: Specifies whether to enable cross-database instance log compression in streaming DR mode.

This parameter applies only to a pair of WAL sender and WAL receiver for cross-database instance transmission in streaming DR and is configured on the primary database instance.

Parameter type: Boolean.

Unit: none

Value range:

• on: Cross-database instance log compression is enabled for streaming DR.
• off: Cross-database instance log compression is disabled for streaming DR.

Default value: off

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Manually enable this function in DR scenarios.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_wal_replication_compression

Parameter description: Specifies whether to enable the Xlog compression function during physical replication between the primary and standby DNs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The log compression function is enabled.
• off: The log compression function is disabled.

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter applies only to a pair of WAL Sender and WAL Receiver threads for data transmission between the primary and standby DNs. Configure this parameter on the primary DN. You are advised not to enable this parameter in scenarios with small Xlogs and delay sensitivity.

Risks and impacts of improper settings: After this parameter is enabled, performance and resources are consumed. Therefore, you need to set wal_replication_compression_thread_settings and wal_replication_compression_settings properly.

• Impact on performance: For details, see the description of the wal_replication_compression_settings parameter.
• Configurations in different resource scenarios: For details, see the description of the wal_replication_compression_thread_settings parameter.

This parameter has the following restrictions:

• Do not modify the compression algorithm during the upgrade.
• DCF is not supported.
• DR databases are not supported.
• You are advised not to enable this function in small specifications (for example, 4 or 8 vCPUs).

wal_replication_compression_thread_settings

Parameter description: Specifies the number of parallel compression threads and single-thread queue depth of the primary and standby databases. This parameter takes effect only when enable_wal_replication_compression is enabled.

Parameter type: string.

Unit: none

Value range: a string of two integers separated by a comma (,). The value ranges of both integer parameters are 1 to 16.

Default value: '1,6'

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter and walsender_max_send_size are used together to specify the memory usage of the compression thread. You need to use this parameter with caution. You are advised to set this parameter to a small value for low-performance machines.

Risks and impacts of improper settings: If this parameter is set to a large value, a large amount of dynamic memory is occupied. As a result, the process cannot be started or the service fails to apply for memory.

wal_replication_compression_settings

Parameter description: Specifies the algorithm rule used for Xlog compression of the primary and standby databases.

Parameter type: string. The parameter value consists of the compression algorithm and compression parameter. The format is 'string,int', for example, 'zstd,5'. Other formats are incorrect, which will cause the setting failure.

Unit: none

Value range: The first parameter (compression algorithm) can be set to lz4 or zstd. Other values are invalid.

• If the first parameter is set to lz4, the second parameter is the acceleration factor and the value ranges from 1 to 300.
• If the first parameter is set to zstd, the second parameter is the compression level and the value ranges from 1 to 15.

Default value: 'lz4,3'

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion:

• A larger acceleration factor of the LZ4 algorithm indicates a lower compression ratio and better performance.
• A higher compression level of the zstd algorithm indicates a higher compression ratio and poorer performance.
• Increasing the compression ratio will reduce the network bandwidth, but the TPS performance will also deteriorate. You are advised to set the compression ratio to the minimum compression ratio that meets the bandwidth requirements.
• The zstd algorithm has a higher compression ratio and more performance degradation, while the lz4 algorithm has a lower compression ratio and less performance degradation.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

repl_auth_mode

Parameter description: Specifies the validation mode for primary/standby replication and standby node rebuilding.

• If UUID validation is enabled on the primary node and a non-null repl_uuid validation code is configured, UUID validation must also be enabled on the standby node and the same repl_uuid validation code must be configured on the standby node. Otherwise, requests for log replication between the primary and standby nodes and standby node rebuilding will be rejected by the primary node.
• The SIGHUP parameter can dynamically load new values. The modification does not affect the established primary/standby connection and takes effect for subsequent primary/standby replication requests and primary/standby rebuilding requests.
• It supports the standby node rebuild validation under the Quorum and DCF protocols and the primary/standby replication validation under the Quorum protocol. It does not support primary/standby replication validation under the DCF protocol.
• Authentication between the primary and standby database instances is not supported, including primary and standby Dorado instances and DR instances.
• The UUID validation function is used to prevent data crosstalk and pollution caused by incorrect connection between the primary and standby nodes. It is not used for security purposes.
• This parameter cannot be automatically synchronized between the primary and standby nodes.

Value type: enumerated type

Unit: none

Value range:

• off: UUID validation is disabled.
• default: UUID validation is disabled.
• uuid: UUID validation is enabled.

Default value: default

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Determine whether to enable this function based on the restrictions in the notice and requirements.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

repl_uuid

Parameter description: Specifies the UUID used for primary/standby UUID validation.

• If UUID validation is enabled on the primary node and a non-null repl_uuid validation code is configured, UUID validation must also be enabled on the standby node and the same repl_uuid validation code must be configured on the standby node. Otherwise, requests for log replication between the primary and standby nodes and standby node rebuilding will be rejected by the primary node.
• The SIGHUP parameter can dynamically load new values. The modification does not affect the established primary/standby connection and takes effect for subsequent primary/standby replication requests and primary/standby rebuilding requests.
• It supports the standby node rebuild validation under the Quorum and DCF protocols and the primary/standby replication validation under the Quorum protocol. It does not support primary/standby replication validation under the DCF protocol.
• Authentication between the primary and standby database instances is not supported, including primary and standby Dorado instances and DR instances.
• The UUID validation function is used to prevent data crosstalk and pollution caused by incorrect connection between the primary and standby nodes. It is not used for security purposes.
• This parameter cannot be automatically synchronized between the primary and standby nodes.

Parameter type: string.

Unit: none

Value range: a string of 0 to 63 case-insensitive letters and digits. It is converted to lowercase letters for storage. An empty string indicates that UUID validation is disabled.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Determine whether to enable this function based on the restrictions in the notice and requirements.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

replconninfo1

Parameter description: Specifies the information about the first node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo1 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the first node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo2

Parameter description: Specifies the information about the second node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo2 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the second node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo3

Parameter description: Specifies the information about the third node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo3 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the third node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo4

Parameter description: Specifies the information about the fourth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo4 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fourth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo5

Parameter description: Specifies the information about the fifth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo5 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fifth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo6

Parameter description: Specifies the information about the sixth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo6 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the sixth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo7

Parameter description: Specifies the information about the seventh node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo7 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the seventh node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo8

Parameter description: Specifies the information about the eighth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo8 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the eighth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo9

Parameter description: Specifies the information about the ninth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo9 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the ninth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo10

Parameter description: Specifies the information about the tenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo10 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the tenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo11

Parameter description: Specifies the information about the eleventh node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo11 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the eleventh node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo12

Parameter description: Specifies the information about the twelfth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo12 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the twelfth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo13

Parameter description: Specifies the information about the thirteenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo13 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the thirteenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo14

Parameter description: Specifies the information about the fourteenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo14 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fourteenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo15

Parameter description: Specifies the information about the fifteenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo15 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fifteenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo16

Parameter description: Specifies the information about the sixteenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo16 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the sixteenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo17

Parameter description: Specifies the information about the seventeenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo17 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the seventeenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

replconninfo18

Parameter description: Specifies the information about the eighteenth node to be listened on and authenticated by the current server. This parameter is automatically configured after the database is successfully installed.

Example:

replconninfo18 = "localhost=XXXX localport=XXXX localheartbeatport=XXXX localservice=XXXX remotehost=XXXX remoteport=XXXX remoteheartbeatport=XXXX remoteservice=XXXX"

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the eighteenth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo1

Parameter description: Specifies the information about the local first node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the first node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo2

Parameter description: Specifies the information about the local second node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the second node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo3

Parameter description: Specifies the information about the local third node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the third node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo4

Parameter description: Specifies the information about the local fourth node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fourth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo5

Parameter description: Specifies the information about the local fifth node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the fifth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo6

Parameter description: Specifies the information about the local sixth node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the sixth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo7

Parameter description: Specifies the information about the local seventh node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the seventh node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

cross_cluster_replconninfo8

Parameter description: Specifies the information about the local eighth node to be listened on and authenticated across database instances.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the eighth node is configured.

Default value: ""

Setting method: This is a SIGHUP parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: The incorrect connection information may cause the abnormal database instance status.

available_zone

Parameter description: Specifies the region where the local node is located.

Parameter type: string.

Unit: none

Value range: a string. An empty string indicates that no information about the node is configured.

Default value: ""

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: If this parameter is incorrectly set, the capability of automatically switching the cascaded standby AZ to another target AZ as the standby AZ is abnormal.

enable_availablezone

Parameter description: Specifies whether the local cascaded standby node can connect to standby nodes across AZs.

Parameter type: Boolean.

Unit: none

Value range:

• on: The cascaded standby node can connect to standby nodes across AZs.
• off: The cascaded standby node can only connect to standby nodes in the same AZ.

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: This parameter is automatically set during installation. You are advised not to change the value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

enable_time_report

Parameter description: Specifies whether to record the time consumed by each redo log.

Parameter type: Boolean.

Unit: none

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: You are advised not to enable the non-debugging mode because the performance deteriorates after the non-debugging mode is enabled.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

thread_top_level

Parameter description: Increases the priority of the WALWRITERAUXILIARY, WALWRITER, STARTUP,WALRECEIVER, WAL_NORMAL_SENDER, and PGSTAT threads to the highest.

Parameter type: Boolean.

Unit: none

Default value: off

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: Change the parameter value after fully understanding the parameter meaning and verifying it through testing.

page_work_queue_size

Parameter description: Specifies the length of the blocking queue of each redo worker.

Parameter type: integer.

Unit: none

Value range: 1 to 100000

Default value: 4096

Setting method: This is a POSTMASTER parameter. Set it based on instructions provided in Table 1.

Setting suggestion: Retain the default value.

Risks and impacts of improper settings: If the value is too small, the pipeline capability becomes invalid. If the value is too large, too much memory is occupied.