Hint list¶

The available hints are listed below.

Group	Format	Description
Scan method	`SeqScan(table)`	Forces sequential scan on the table.
	`TidScan(table)`	Forces TID scan on the table.
	`IndexScan(table[ index...])`	Forces index scan on the table. Restricts to specified indexes if any.
	`IndexOnlyScan(table[ index...])`	Forces index-only scan on the table. Restricts to specified indexes if any. Index scan may be used if index-only scan is not available.
	`BitmapScan(table[ index...])`	Forces bitmap scan on the table. Restricts to specified indexes if any.
	`IndexScanRegexp(table[ POSIX Regexp...])` `IndexOnlyScanRegexp(table[ POSIX Regexp...])` `BitmapScanRegexp(table[ POSIX Regexp...])`	Forces index scan, index-only scan (For PostgreSQL 9.2 and later) or bitmap scan on the table. Restricts to indexes that matches the specified POSIX regular expression pattern.
	`NoSeqScan(table)`	Forces to not do sequential scan on the table.
	`NoTidScan(table)`	Forces to not do TID scan on the table.
	`NoIndexScan(table)`	Forces to not do index scan and index-only scan on the table.
	`NoIndexOnlyScan(table)`	Forces to not do index only scan on the table.
	`NoBitmapScan(table)`	Forces to not do bitmap scan on the table.
Join method	`NestLoop(table table[ table...])`	Forces nested loop for the joins on the tables specified.
	`HashJoin(table table[ table...])`	Forces hash join for the joins on the tables specified.
	`MergeJoin(table table[ table...])`	Forces merge join for the joins on the tables specified.
	`NoNestLoop(table table[ table...])`	Forces to not do nested loop for the joins on the tables specified.
	`NoHashJoin(table table[ table...])`	Forces to not do hash join for the joins on the tables specified.
	`NoMergeJoin(table table[ table...])`	Forces to not do merge join for the joins on the tables specified.
Join order	`Leading(table table[ table...])`	Forces join order as specified.
	`Leading(<join pair>)`	Forces join order and directions as specified. A join pair is a pair of tables and/or other join pairs enclosed by parentheses, which can make a nested structure.
Behavior control on Join	`Memoize(table table[ table...])`	Allows the topmost join of a join among the specified tables to Memoize the inner result. Not enforced.
	`NoMemoize(table table[ table...])`	Inhibits the topmost join of a join among the specified tables from Memoizing the inner result.
Row number correction	`Rows(table table[ table...] correction)`	Corrects row number of a result of the joins on the tables specified. The available correction methods are absolute (#), addition (+), subtract (-) and multiplication (*). should be a string that strtod() can understand.
Parallel query configuration	`Parallel(table <# of workers> [soft\|hard])`	Enforces or inhibits parallel execution of the specified table. <# of workers> is the desired number of parallel workers, where zero means inhibiting parallel execution. If the third parameter is soft (default), it just changes max_parallel_workers_per_gather and leaves everything else to the planner. Hard enforces the specified number of workers.
GUC	`Set(GUC-param value)`	Sets GUC parameter to the value defined while planner is running.