enable_bitmapscan — PostgreSQL configuration parameter

Enables or disables the query planner’s use of bitmap-scan plan types.

At a glance

What it does

Enables or disables the query planner’s use of bitmap-scan plan types. The default is on.

(Description quoted from the official PostgreSQL documentation.)

How to apply a change

Can be set per session with SET, per role/database with ALTER ROLE/DATABASE ... SET, or globally in postgresql.conf.

Inspect the current value and source with SHOW enable_bitmapscan; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'enable_bitmapscan';.

Tuning guidance

This is a diagnostic switch, not a production tuning knob. Turn it off briefly (per session) to confirm why the planner avoids or prefers a plan, then leave it on. Forcing it off in production masks bad estimates instead of fixing them — fix statistics, costs or indexes instead.

Reference

PostgreSQL documentation — enable_bitmapscan.