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PostgreSQL Reference Manual - Volume 3 - Server Administration Guide
by The PostgreSQL Global Development Group
Paperback (6"x9"), 204 pages
ISBN 0954612043
RRP £13.95 ($24.95)

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4.6.1 Planner Method Configuration

These configuration parameters provide a crude method of influencing the query plans chosen by the query optimizer. If the default plan chosen by the optimizer for a particular query is not optimal, a temporary solution may be found by using one of these configuration parameters to force the optimizer to choose a different plan. Turning one of these settings off permanently is seldom a good idea, however. Better ways to improve the quality of the plans chosen by the optimizer include adjusting the section 4.6.2 Planner Cost Constants, running ANALYZE more frequently, increasing the value of the default_statistics_target configuration parameter, and increasing the amount of statistics collected for specific columns using ALTER TABLE SET STATISTICS.

enable_bitmapscan (boolean)
Enables or disables the query planner's use of bitmap-scan plan types. The default is on.
enable_hashagg (boolean)
Enables or disables the query planner's use of hashed aggregation plan types. The default is on.
enable_hashjoin (boolean)
Enables or disables the query planner's use of hash-join plan types. The default is on.
enable_indexscan (boolean)
Enables or disables the query planner's use of index-scan plan types. The default is on.
enable_mergejoin (boolean)
Enables or disables the query planner's use of merge-join plan types. The default is on.
enable_nestloop (boolean)
Enables or disables the query planner's use of nested-loop join plans. It's not possible to suppress nested-loop joins entirely, but turning this variable off discourages the planner from using one if there are other methods available. The default is on.
enable_seqscan (boolean)
Enables or disables the query planner's use of sequential scan plan types. It's not possible to suppress sequential scans entirely, but turning this variable off discourages the planner from using one if there are other methods available. The default is on.
enable_sort (boolean)
Enables or disables the query planner's use of explicit sort steps. It's not possible to suppress explicit sorts entirely, but turning this variable off discourages the planner from using one if there are other methods available. The default is on.
enable_tidscan (boolean)
Enables or disables the query planner's use of TID scan plan types. The default is on.
ISBN 0954612043PostgreSQL Reference Manual - Volume 3 - Server Administration GuideSee the print edition