Cookbook recipe

Speed up COUNT(*) on large tables

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

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Estimated investigation4 min

Scenario

SELECT COUNT(*) on a 200M-row table takes minutes. Exact counts are expensive in MVCC; pick the right trade-off. Diagnose it For an approximate live count, read the planner estimate: SELECT reltuples::bigint AS approx_rows FROM pg_class WHERE…

Investigation Path

SELECT COUNT(*) on a 200M-row table takes minutes. Exact counts are expensive in MVCC; pick the right trade-off.

Diagnose it

For an approximate live count, read the planner estimate:

SELECT reltuples::bigint AS approx_rows
FROM pg_class WHERE relname = 'events';

Why it happens

Because of MVCC, PostgreSQL must verify visibility of each row to count exactly, so COUNT(*) scans the table (or a covering index). There is no maintained row counter.

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Related & next steps

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