All Your GUCs in a Row: max_parallel_maintenance_workers

A deep technical breakdown of PostgreSQL's max_parallel_maintenance_workers parameter explains how it caps parallel workers for index builds, VACUUM, and related commands. It covers the interaction with maintenance_work_mem, the table-size ladder that determines worker requests, differences between VACUUM and index build worker allocation, autovacuum's lack of parallelism through PostgreSQL 18 (and new support via autovacuum_max_parallel_workers in PostgreSQL 19), and practical pitfalls with pg_restore -j oversubscribing the worker pool. Includes concrete numbers, version history (11, 13, 17, 18, 19 beta 3), and diagnostic techniques using debug1 logging and pg_stat_activity.

Source: https://postgr.es/p/9v7. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.