Miscellaneous Parameters¶
enable_cluster_resize¶
Parameter description: Indicates whether the current session is a scale-out redistribution session. This parameter applies only to scale-out redistribution sessions. Do not set this parameter for other service sessions.
Type: SUSET
Value range: Boolean
on indicates that the current session is for scaling or redistributing data, and allows the execution of specific SQL statements for redistribution.
off indicates that the current session is not for scaling or redistributing data, and does not allow the execution of specific SQL statements for redistribution.
Default value: off
Note
This parameter is used for internal O&M. Do not set it to on unless absolutely necessary.
dfs_partition_directory_length¶
Parameter description: Specifies the largest directory name length for the partition directory of a table partitioned by VALUE in the HDFS.
Type: USERSET
Value range: 92 to 7999
Default value: 512
enable_hadoop_env¶
Parameter description: Sets whether local row- and column-store tables can be created in a database while the Hadoop feature is used. In the GaussDB(DWS) cluster, it is set to off by default to support local row- and column- based storage and cross-cluster access to Hadoop. You are not advised to change the value of this parameter.
Type: USERSET
Value range: Boolean
on or true, indicating that local row- and column-store tables cannot be created in a database while the Hadoop feature is used.
off or false, indicating that local row- and column-based tables can be created in a database while the Hadoop feature is used.
Default value: off
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 avoided when update and delete operations are performed at the same time.
Type: USERSET
Value range: Boolean
If this parameter is set to on, the delta merge operation internally increases the lock level. In this way, when any two of the DELTAMERGE, UPDATE, and DELETE operations are concurrently performed, an 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
job_queue_processes¶
Parameter description: Specifies the number of jobs that can be concurrently executed.
Type: POSTMASTER
Value range: 0 to 1000
Functions:
Setting job_queue_processes to 0 indicates that the scheduled task function is disabled and that no job will be executed. (Enabling scheduled tasks may affect the system performance. At sites where this function is not required, you are advised to disable it.)
Setting job_queue_processes to a value that is greater than 0 indicates that the scheduled task function is enabled and this value is the maximum number of tasks that can be concurrently processed.
After the scheduled task function is enabled, the job_scheduler thread at a scheduled interval polls the pg_jobs system catalog. The scheduled task check is performed every second by default.
Too many concurrent tasks consume many system resources, so you need to set the number of concurrent tasks to be processed. If the current number of concurrent tasks reaches job_queue_processes and some of them expire, these tasks will be postponed to the next polling period. Therefore, you are advised to set the polling interval (the interval parameter of the submit interface) based on the execution duration of each task to avoid the problem that tasks in the next polling period cannot be properly processed because overlong task execution time.
Note: If the number of parallel jobs is large and the value is too small, these jobs will wait in queues. However, a large parameter value leads to large resource consumption. You are advised to set this parameter to 100 and change it based on the system resource condition.
Default value: 10
ngram_gram_size¶
Parameter description: Specifies the length of the ngram parser segmentation.
Type: USERSET
Value range: an integer ranging from 1 to 4
Default value: 2
ngram_grapsymbol_ignore¶
Parameter description: Specifies whether the ngram parser ignores graphical characters.
Type: USERSET
Value range: Boolean
on: Ignores graphical characters.
off: Does not ignore graphical characters.
Default value: off
ngram_punctuation_ignore¶
Parameter description: Specifies whether the ngram parser ignores punctuations.
Type: USERSET
Value range: Boolean
on: Ignores punctuations.
off: Does not ignore punctuations.
Default value: on
zhparser_dict_in_memory¶
Parameter description: Specifies whether Zhparser adds a dictionary to memory.
Type: POSTMASTER
Value range: Boolean
on: Adds the dictionary to memory.
off: Does not add the dictionary to memory.
Default value: on
zhparser_multi_duality¶
Parameter description: Specifies whether Zhparser aggregates segments in long words with duality.
Type: USERSET
Value range: Boolean
on: Aggregates segments in long words with duality.
off: Does not aggregate segments in long words with duality.
Default value: off
zhparser_multi_short¶
Parameter description: Specifies whether Zhparser executes long words composite divide.
Type: USERSET
Value range: Boolean
on: Performs compound segmentation for long words.
off: Does not perform compound segmentation for long words.
Default value: on
zhparser_multi_zall¶
Parameter description: Specifies whether Zhparser displays all single words individually.
Type: USERSET
Value range: Boolean
on: Displays all single words separately.
off: Does not display all single words separately.
Default value: off
zhparser_multi_zmain¶
Parameter description: Specifies whether Zhparser displays important single words separately.
Type: USERSET
Value range: Boolean
on: Displays important single words separately.
off: Does not display important single words separately.
Default value: off
zhparser_punctuation_ignore¶
Parameter description: Specifies whether the Zhparser segmentation result ignores special characters including punctuations (\r and \n will not be ignored).
Type: USERSET
Value range: Boolean
on: Ignores all the special characters including punctuations.
off: Does not ignore all the special characters including punctuations.
Default value: on
zhparser_seg_with_duality¶
Parameter description: Specifies whether Zhparser aggregates segments in long words with duality.
Type: USERSET
Value range: Boolean
on: Aggregates segments in long words with duality.
off: Does not aggregate segments in long words with duality.
Default value: off
acceleration_with_compute_pool¶
Parameter description: Specifies whether to use the computing resource pool for acceleration when OBS is queried.
Type: USERSET
Value range: Boolean
on indicates that the query covering OBS is accelerated based on the cost when the computing resource pool is available.
off indicates that no query is accelerated using the computing resource pool.
Default value: off
redact_compat_options¶
Parameter description: Specifies the compatibility option for calculation using masked data. This parameter is supported only by clusters of version 8.1.3.310 or later.
Type: USERSET
Value range: a string
none indicates that compatibility options are specified.
disable_comparison_operator_mask indicates that comparison operators that do not expose raw data can bypass the data masking check and generate the actual calculation result.
Default value: none
table_skewness_warning_threshold¶
Parameter description: Specifies the threshold for triggering a table skew alarm.
Type: SUSET
Value range: a floating point number ranging from 0 to 1
Default value: 1
table_skewness_warning_rows¶
Parameter description: Specifies the minimum number of rows for triggering a table skew alarm.
Type: SUSET
Value range: an integer ranging from 0 to INT_MAX
Default value: 100000
auto_process_residualfile¶
Parameter description: Specifies whether to enable the residual file recording function.
Type: SIGHUP
Value range: Boolean
on indicates that the residual file recording function is enabled.
off indicates that the residual file recording function is disabled.
Default value: off
enable_view_update¶
Parameter description: Enables the view update function or not.
Type: POSTMASTER
Value range: Boolean
on indicates that the view update function is enabled.
off indicates that the view update function is disabled.
Default value: off
view_independent¶
Parameter description: Decouples views from tables, functions, and synonyms or not. After the base table is restored, automatic association and re-creation are supported.
Type: SIGHUP
Value range: Boolean
on indicates that the view decoupling function is enabled. Tables, functions, synonyms, and other views on which views depend can be deleted separately (except temporary tables and temporary views). Associated views are reserved but unavailable.
off indicates that the view decoupling function is disabled. Tables, functions, synonyms, and other views on which views depend cannot be deleted separately. You can only delete them in the cascade mode.
Default value: off
bulkload_report_threshold¶
Parameter description: Sets the threshold for reporting import and export statistics. When the data volume exceeds this threshold, the PGXC_BULKLOAD_STATISTICS view can be used to query synchronized data volume, record count, execution time, and other information.
Type: SIGHUP
Value range: an integer ranging from 0 to INT_MAX
Default value: 50
assign_abort_xid¶
Parameter description: Determines the transaction to be aborted based on the specified XID in a query.
Type: USERSET
Value range: a character string with the specified XID
Caution
This parameter is used only for quick restoration if a user deletes data by mistake (DELETE operation). Do not use this parameter in other scenarios. Otherwise, visible transaction errors may occur.
default_distribution_mode¶
Parameter description: Specifies the default distribution mode of a table. This feature is supported only in 8.1.2 or later.
Type: USERSET
Value range: enumerated values
roundrobin: If the distribution mode is not specified during table creation, the default distribution mode is selected according to the following rules:
If the primary key or unique constraint is included during table creation, hash distribution is selected. The distribution column is the column corresponding to the primary key or unique constraint.
If the primary key or unique constraint is not included during table creation, round-robin distribution is selected.
hash: If the distribution mode is not specified during table creation, the default distribution mode is selected according to the following rules:
If the primary key or unique constraint is included during table creation, hash distribution is selected. The distribution column is the column corresponding to the primary key or unique constraint.
If the primary key or unique constraint is not included during table creation but there are columns whose data types can be used as distribution columns, hash distribution is selected. The distribution column is the first column whose data type can be used as a distribution column.
If the primary key or unique constraint is not included during table creation and no column whose data type can be used as a distribution column exists, round-robin distribution is selected.
Default value: roundrobin
Note
The default value of this parameter is roundrobin for a new GaussDB(DWS) 8.1.2 cluster and is hash for an upgrade to GaussDB(DWS) 8.1.2.
max_volatile_tables¶
Parameter description: Specifies the maximum number of volatile tables created for each session, including volatile tables and their auxiliary tables. This parameter is supported by version 8.2.0 or later clusters.
Type: USERSET
Value range: an integer ranging from 0 to INT_MAX
Default value: 300