Postgres vacuum cheat sheet.md

PostgreSQL VACUUM ANALYZE & Debug Cheatsheet

Last updated: 2025-05-10 14:16:59 UTC

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✅ Connect to a Different Database with Elevated Permissions

\c your_db your_writer_user

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🧼 Run VACUUM ANALYZE on the Current DB

VACUUM ANALYZE;

⚠️ If you see permission denied, you need to connect as a user with elevated rights.

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🔍 Check Tables Not Yet Vacuumed/Analyzed

SELECT
  current_database() AS db,
  COUNT(*) FILTER (
    WHERE last_vacuum IS NULL OR last_analyze IS NULL
  ) AS tables_not_vacuumed,
  COUNT(*) AS total_tables
FROM
  pg_stat_user_tables;

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📋 See Last Vacuum and Analyze Timestamps

SELECT relname, last_vacuum, last_analyze
FROM pg_stat_user_tables
ORDER BY last_analyze DESC;

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🔧 Check Autovacuum Settings

SHOW autovacuum;
SHOW autovacuum_vacuum_threshold;
SHOW autovacuum_analyze_threshold;
SHOW autovacuum_vacuum_scale_factor;
SHOW autovacuum_analyze_scale_factor;

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🔁 Script to VACUUM Across Multiple Databases

For each database:

psql -U your_writer_user -d dbname -h writer.cluster-xyz.rds.amazonaws.com -c "VACUUM ANALYZE;"

Or interactively inside psql:

\c dbname your_writer_user
VACUUM ANALYZE;

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🔐 Optional: Setup .pgpass to Avoid Repeated Password Prompts

Create ~/.pgpass with:

your-host:5432:*:your_writer_user:yourpassword

Then:

chmod 600 ~/.pgpass

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