pg_repack in POSTGRESQL DBA

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• 12 Jun, 2025
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• 1 Min Read

pg_repack in POSTGRESQL DBA

pg_repack is a powerful PostgreSQL extension that allows you to reclaim space and optimize table performance without requiring heavy locks or downtime. It’s especially useful for removing table and index bloat caused by frequent UPDATE and DELETE operations.`

What is pg_repack?

• A non-blocking tool that physically rewrites tables and indexes to remove dead tuples.

• Unlike VACUUM FULL, it does not lock writes, making it safe for production use.

• Rebuilds tables/indexes in the background using a shadow copy, then swaps it in.

Why is it needed?

• PostgreSQL uses MVCC (Multi-Version Concurrency Control) to handle concurrent updates/deletes.

• When rows are deleted or updated, old row versions remain as dead tuples, leading to bloat.

• VACUUM clears these, but doesn’t shrink the physical table size.

• VACUUM FULL reclaims space but locks the table, which is not suitable for production.

• pg_repack solves this by:

  • Creating a shadow copy of the table.

  • Rebuilding it in the background.

  • Swapping it in with minimal locking.

 

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