Postgres Vacuum vs Autovacuum

Tuning vacuum.

Overview

Postgres autovacuum runs by default; that does not make it tuned. The discipline is recognising when default autovacuum suffices, when per-table tuning is required, and when explicit manual vacuum is the right move.

• Autovacuum default. Postgres runs autovacuum on its own schedule. Sufficient for low-write tables.
• Per-table tuning. High-write tables need aggressive autovacuum settings. The defaults are too lazy under heavy write load.
• Manual vacuum. Before bulk operations or after large batch updates. Autovacuum will not run on the timeline a bulk operation needs.
• VACUUM ANALYZE. Updates planner statistics in addition to reclaiming space. Run after large data changes for accurate query plans.

The approach

Three habits keep Postgres vacuum healthy: per-table tuning for the high-write tables, continuous bloat monitoring, and manual vacuum at known stress points.

• Per-table tuning. autovacuum_vacuum_scale_factor at 0.05 or lower for write-heavy tables. The defaults are too generous.
• Monitor bloat. Per-table dead-tuple percentage on the database dashboard. Alert at 20 percent for high-traffic tables.
• Manual vacuum at known points. Before bulk inserts or after large update batches. VACUUM (ANALYZE) updates statistics at the same time.
• Monthly ANALYZE plus documented strategy. Manual ANALYZE monthly catches statistics drift; per-table strategy lives in the runbook.

Why this compounds

Each tuned table produces ongoing query-performance benefit. Patterns transfer across Postgres deployments; new tables ship with the right settings instead of the global defaults.

• Faster queries. Less bloat means more index-scans where index-scans should happen. p99 query time benefits.
• Storage efficiency. Less bloat means less storage. The savings continue every month.
• Stability. Aggressive autovacuum prevents transaction-wraparound emergencies that show up as full-database freezes.
• Year-one investment, year-two habit. The first tuning is heavy lift. By the third table, the team knows the knobs and the right values reflexively.