Miscellaneous Parameters

server_version

Parameter description: Specifies the server version number.

This parameter is a fixed INTERNAL parameter and cannot be modified. This parameter is inherited from the PostgreSQL kernel, indicating that the current database kernel is compatible with PostgreSQL's server_version. This parameter is reserved to ensure the ecosystem compatibility of the northbound external tool APIs (which will be queried when the tool is connected). This parameter is not recommended. You can use the opengauss_version() function to obtain the kernel version.

Value range: a string

Default value: 9.2.4

server_version_num

Parameter description: Specifies the server version number.

This parameter is a fixed INTERNAL parameter and cannot be modified. This parameter is inherited from the PostgreSQL kernel, indicating that the current database kernel is compatible with PostgreSQL's server_version_num. This parameter is reserved to ensure the ecosystem compatibility of the northbound external tool APIs (which will be queried when the tool is connected).

Value range: an integer

Default value: 90204

block_size

Parameter description: Specifies the block size of the current database.

This parameter is a fixed INTERNAL parameter and cannot be modified. This parameter is inherited from the PostgreSQL kernel, indicating that the current database kernel is compatible with PostgreSQL's server_version_num. This parameter is reserved to ensure the ecosystem compatibility of the northbound external tool APIs.

Default value: 8192

segment_size

Parameter description: Specifies the segment file size of the current database.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Default value: 1 GB

max_index_keys

Parameter description: Specifies the maximum number of index keys supported by the current database.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Default value: 32

integer_datetimes

Parameter description: Specifies whether the date and time are in the 64-bit integer format.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Value range: Boolean

• on indicates that the 64-bit integer format is used.
• off indicates that the 64-bit integer format is not used.

Default value: on

enable_cluster_resize

Parameter description: If an SQL statement involves tables belonging to different groups, you can enable this parameter to push the execution plan of the statement to improve performance.

This parameter is a SUSET parameter. Set it based on instructions provided in Table 1.

Value range: Boolean

• on indicates that the execution plan of the statement can be pushed.
• off indicates that the execution plan of the statement cannot be pushed.

Default value: off

This parameter is used for internal O&M. Do not set it to on unless absolutely necessary.

lc_collate

Parameter description: Specifies the locale in which sorting of textual data is done.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Default value: Determined by the configuration set during the cluster installation and deployment.

lc_ctype

Parameter description: Specifies the locale that determines character classifications. For example, it specifies what a letter and its upper-case equivalent are.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Default value: Determined by the configuration set during the cluster installation and deployment.

max_identifier_length

Parameter description: Specifies the maximum identifier length.

This parameter is a fixed INTERNAL parameter and cannot be modified.

Value range: an integer

Default value: 63

server_encoding

Parameter description: Specifies the database encoding (character set).

This parameter is a fixed INTERNAL parameter and cannot be modified.

Default value: Determined when the database is created.

enable_upgrade_merge_lock_mode

Parameter description: If this parameter is set to on, the delta merge operation internally increases the lock level, and errors can be prevented when update and delete operations are performed at the same time.

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

Value range: Boolean

• If this parameter is set to on, the delta merge operation internally increases the lock level. In this way, when the DELTAMERGE operation is concurrently performed with the UPDATE or DELETE operation, one operation can be performed only after the previous one is complete.
• If this parameter is set to off and the DELTAMERGE operation is concurrently performed with the UPDATE or DELETE operation to the data in a row in the delta table of the table, errors will be reported during the later operation, and the operation will stop.

Default value: off

transparent_encrypted_string

Parameter description: Specifies a sample string that is transparently encrypted. Its value is generated by encrypting TRANS_ENCRYPT_SAMPLE_STRING using a database secret key. The ciphertext is used to check whether the DEK obtained during secondary startup is correct. If the DEK is incorrect, CNs and DNs reject the startup. This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1. This parameter applies only to the DWS scenario in the current version.

Value range: a string. An empty string indicates that the entire cluster is encrypted.

Default value: empty

Do not set this parameter manually. Otherwise, the cluster may become faulty.

transparent_encrypt_kms_url

Parameter description: Specifies the URL for obtaining the database secret key to be transparently encrypted. It must contain only the characters specified in RFC3986, and the maximum length is 2047 bytes. The format is kms://Protocol@KMS host name 1;KMS host name 2:KMS port number/kms, for example, kms://https@linux175:29800/. This parameter applies only to the DWS scenario in the current version.

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

Value range: a string

Default value: empty

transparent_encrypt_kms_region

Parameter description: Specifies the deployment region of the entire cluster. It must contain only the characters specified in RFC3986, and the maximum length is 2047 bytes. This parameter applies only to the DWS scenario in the current version.

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

Value range: a string

Default value: empty

datanode_heartbeat_interval

Parameter description: Specifies the interval at which heartbeat messages are sent between heartbeat threads. You are advised to set this parameter to a value no more than wal_receiver_timeout/2.

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

Value range: an integer ranging from 1000 to 60000. The unit is ms.

Default value: 1s

dfs_partition_directory_length

Parameter description: Specifies the maximum directory name length for the partition directory of a table partitioned by VALUE in the HDFS.

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

Value range: 92 to 7999

Default value: 512

max_concurrent_autonomous_transactions

Parameter description: Specifies the maximum number of autonomous transaction connections, that is, the maximum number of concurrent autonomous transactions executed at the same time. If this parameter is set to 0, autonomous transactions cannot be executed.

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

Value range: 0–1024

Default value: 10

mot_config_file

This parameter is unavailable in a distributed system.