Schedule - PGConf.DE 2025
Modern VACUUM
Date: 2025-05-08
Time: 12:50–13:35
Room: Ballsaal 3
Level: Intermediate
One or two decades ago, PostgreSQL's VACUUM was a simple process that would scan an entire table and clean up no-longer-visible tuple versions from the table and its indexes. Once every 200 Million transactions, an additional full table scan was required to freeze old transaction IDs to prevent wraparound of the transaction counter.
Over time, this seemingly simple process was optimized. VACUUM now knows about which pages have to be visited for vacuuming and freezing. Runs can be sped up by skipping indexes and toast tables. Various phases of runs can profit from parallelization. Autovacuum has learned to process insert-only tables. Emergency freeze runs are much less scary than in the past.
In this talk, we shed light on these new modern VACUUM features and how DBAs profit from a much better performance.