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The PostgreSQL 9.0 Reference Manual - Volume 3 - Server Administration Guide
by The PostgreSQL Global Development Group
Paperback (6"x9"), 274 pages
ISBN 9781906966072
RRP £9.95 ($14.95)

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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 is to use one of these configuration parameters to force the optimizer to choose a different plan. Better ways to improve the quality of the plans chosen by the optimizer include adjusting the planer cost constants (see section 4.6.2 Planner Cost Constants), running ANALYZE manually, 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_material (boolean)
Enables or disables the query planner's use of materialization. It is impossible to suppress materialization entirely, but turning this variable off prevents the planner from inserting materialize nodes except in cases where it is required for correctness. 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 is impossible 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 is impossible 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 is impossible 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 9781906966072The PostgreSQL 9.0 Reference Manual - Volume 3 - Server Administration GuideSee the print edition