Cookbook recipe

The visibility map and freezing explained

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.

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Estimated investigation4 min

Scenario

Index-only scans and fast vacuums both depend on the visibility map. Understanding it explains a lot of PostgreSQL behavior. Diagnose it See frozen/all-visible info indirectly via vacuum verbose: VACUUM (VERBOSE) orders; -- reports pages skipped via…

Investigation Path

Index-only scans and fast vacuums both depend on the visibility map. Understanding it explains a lot of PostgreSQL behavior.

Diagnose it

See frozen/all-visible info indirectly via vacuum verbose:

VACUUM (VERBOSE) orders;  -- reports pages skipped via visibility map

Why it happens

The visibility map marks pages where every tuple is visible to all transactions (all-visible) and, separately, all-frozen. VACUUM can skip all-visible pages, and index-only scans can avoid the heap for them.

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Related & next steps

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Concepts on this page

Visibility map Autovacuum Transaction ID wraparound VACUUM Tuple
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