Sets the planner’s estimate of the cost of transferring one tuple from a parallel worker process to another process.
At a glance
| Property | Value |
|---|---|
| Parameter | parallel_tuple_cost |
| Category | Query Planning |
| Default | 0.1 |
| Value type | floating point |
| Change scope | Per-session (SET) |
| Available in | PostgreSQL 12, 13, 14, 15, 16, 17, 18, 19 (added in 12) |
What it does
Sets the planner’s estimate of the cost of transferring one tuple from a parallel worker process to another process. The default is 0.1.
(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 parallel_tuple_cost; or SELECT name, setting, unit, context, source FROM pg_settings WHERE name = 'parallel_tuple_cost';.
Tuning guidance
Reduce it to encourage parallel plans that move many rows from workers to the leader; raise it when Gather is the bottleneck. Tune together with parallel_setup_cost.