autovacuum
Parameter description: Specifies whether to start the automatic cleanup process (autovacuum).
Type: SIGHUP
Value range: Boolean
- on indicates the database automatic cleanup process is enabled.
- off indicates that the database automatic cleanup process is disabled.
Default value: on
autovacuum_max_workers
Parameter description: Specifies the maximum number of autovacuum worker threads that can run at the same time. The upper limit of this parameter is related to the values of max_connections and job_queue_processes.
Type: SIGHUP
Value range: an integer
- The minimum value is 0, indicating that autovacuum is not automatically performed.
- The theoretical maximum value is 262143, and the actual maximum value dynamically changes. Formula: 262143 - max_inner_tool_connections - max_connections - job_queue_processes - auxiliary threads - Number of autovacuum launcher threads - 1. The number of auxiliary threads and the number of autovacuum launcher threads are specified by two macros. Their default values in the current version are 20 and 2, respectively.
Default value: 3
autovacuum_max_workers_hstore
Parameter description: Specifies the maximum number of concurrent automatic cleanup threads used for hstore tables in autovacuum_max_workers.
Type: SIGHUP
Value range: an integer
Default value: 0
To use HStore tables, set the following parameters, or the HStore performance will deteriorate severely. The recommended settings are as follows:
autovacuum_max_workers_hstore=3, autovacuum_max_workers=6, autovacuum=true
enable_hstore_lightupdate
Parameter description: Specifies whether to enable lightweight UPDATE for an HStore table. (When an UPDATE operation is performed on an HStore table, the system automatically determines whether lightweight UPDATE is required.)
Type: SIGHUP
Value range: Boolean
- on indicates that lightweight UPDATE is enabled for hstore tables.
- off indicates that lightweight UPDATE is disabled for hstore tables.
Default value: off
enable_hstore_merge_keepgtm
Parameter description: Specifies whether the MERGE in the autovacuum operation on column-store and hstore tables occupies slots in the GTM.
Type: SIGHUP
Value range: Boolean
- true indicates that it occupies slots in the GTM.
- false indicates that it does not occupy slots in the GTM.
Default value: true
hstore_buffer_size
Parameter description: Specifies the number of HStore CU slots. The slots are used to store the update chain of each CU, which significantly improves the update and query efficiency.
To prevent excessive memory usage, the system calculates a slot value based on the memory size, compares the slot value with the value of this parameter, and uses the smaller value of the two.
Type: POSTMASTER
Value range: an integer ranging from 100 to 10,000,000
Default value: 100,000