Miscellaneous Parameters

enable_default_ustore_table

Parameter description: Specifies whether to enable the UStore storage engine by default. If this parameter is set to on, all created tables are UStore tables.

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

Value range: [off,on]

Default value: off

reserve_space_for_nullable_atts

Parameter description: Specifies whether to reserve space for the nullable attribute of an Ustore table. If this parameter is set to on, space is reserved for the nullable attribute of the Ustore table by default.

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

Value range: [off,on]

Default value: on

ustore_attr

Parameter description: Specifies the UStore test parameters.

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

You can set enable_ustore_partial_seqscan (copy selective columns only during sequential scanning in the ustore table), enable_candidate_buf_usage_count (whether dirty pages are evicted and added to the use count weight), and ustats_tracker_naptime (time for reloading the statistics file). umax_search_length_for_prune (number of blocks to be pruned before table extension) and ustore_unit_test (starting the UStore white box test). The setting method is ustore_att ='enable_ustore_partial_seqscan=on'.

Value range: a string

server_version

Parameter description: Specifies the server version number.

This parameter is a fixed parameter of the INTERNAL type. It can be viewed but cannot be modified. This parameter is inherited from the PostgreSQL kernel, indicating that the current database kernel is compatible with the server_version version corresponding to PostgreSQL. This parameter is reserved to ensure the ecosystem compatibility of the northbound external tool interface (query when the tool is connected). This parameter is not recommended. To query the server version, use the opengauss_version() function.

Value range: a string

Default value: 9.2.4

server_version_num

Parameter description: Specifies the server version number.

This parameter is a fixed parameter of the INTERNAL type. It can be viewed but cannot be modified. This parameter is inherited from the PostgreSQL kernel, indicating that the current database kernel is compatible with the server_version_num version corresponding to PostgreSQL. This parameter is reserved to ensure the ecosystem compatibility of the northbound external tool API. (query 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 an INTERNAL parameter. The value of this parameter cannot be modified.

Value:8192

Default value: 8192

segment_size

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

This parameter is an INTERNAL parameter. The value of this parameter cannot be modified.

Unit: 8 KB

Default value: 131072, that is, 1 GB

max_index_keys

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

This parameter is an INTERNAL parameter. The value of this parameter 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 an INTERNAL parameter. The value of this parameter 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

lc_collate

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

This parameter is an INTERNAL parameter. The value of this parameter cannot be modified.

Default value: Determined by the configuration set during the MogDB 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 an INTERNAL parameter. The value of this parameter cannot be modified.

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

max_identifier_length

Parameter description: Specifies the maximum identifier length.

This parameter is an INTERNAL parameter. The value of this parameter cannot be modified.

Value range: an integer

Default value: 63

server_encoding

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

By default, gs_initdb will initialize the setting of this parameter based on the current system environment. You can also run the locale command to check the current configuration environment.

This parameter is an INTERNAL parameter. The value of this parameter cannot be modified.

Default value: determined by the current system environment 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 GUC parameters.

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 any two of the DELTAMERGE, UPDATE, and DELETE operations are concurrently performed to data in a row in the delta table of the HDFS 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 it is incorrect, database nodes will not be started. This parameter is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: a string. An empty string indicates that MogDB is a not encrypted.

Default value: empty

NOTE: Do not set this parameter manually. Otherwise, MogDB 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 is a POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: a string

Default value: empty

transparent_encrypt_kms_region

Parameter description: Specifies the deployment region of MogDB. It must contain only the characters specified in RFC3986, and the maximum length is 2047 bytes.

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

Value range: a string

Default value: empty

basebackup_timeout

Parameter description: Specifies the timeout period for connection during which no read/write operations are performed after backup transmission is complete. When the gs_basebackup tool is used for transmission, if a higher compression rate is specified, the timeout may occur after the tablespace transmission is complete. (The transmission data needs to be compressed in the client.)

Value range: an integer ranging from 0 to INT_MAX. The unit is second. 0: indicates that the parameter is disabled.

Default value: 600s

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 GUC parameters.

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

Default value: 1s

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 an POSTMASTER parameter. Set it based on instructions provided in Table 1 GUC parameters.

Value range: 0-1024

Default value: 10