Cookbook recipe

What ANALYZE collects and why plans depend on it

Applies to PostgreSQL 13–17 Last reviewed May 2026 Grounded in source

What This Is

A production experience capsule based on real incident patterns.

Why It Matters

Builds production judgment under pressure.

Next Step

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Estimated investigation4 min

Scenario

After a big data load, queries suddenly pick terrible plans. The statistics are stale — ANALYZE fixes the planner's view of your data. Diagnose it See when stats were last gathered: SELECT relname, last_analyze, last_autoanalyze FROM…

Investigation Path

After a big data load, queries suddenly pick terrible plans. The statistics are stale — ANALYZE fixes the planner’s view of your data.

Diagnose it

See when stats were last gathered:

SELECT relname, last_analyze, last_autoanalyze
FROM pg_stat_user_tables ORDER BY last_analyze NULLS FIRST;

Why it happens

The planner estimates costs from statistics: row counts, most-common values, histograms, and distinct counts. After bulk changes those stats are stale, so estimates — and the chosen plans — go wrong until ANALYZE refreshes them.

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Career Impact

This scenario builds production judgment and operational confidence under pressure.

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Concepts on this page

Statistics target Extended statistics Autovacuum Query planner Schema
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