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Software Engineering Concept

PostgreSQL TOAST

JourneySoftware engineering Statuslearning Tags
  • database
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The Oversized-Attribute Storage Technique. PostgreSQL's mechanism for handling large column values that exceed the page size (8 KB).

How It Works ​

  • When a row contains a value larger than ~2 KB, PostgreSQL automatically compresses it and/or moves it to a separate TOAST table.

  • This happens transparently. The application does not need to know about TOAST.

  • The original row stores a pointer to the TOAST table.

Limits ​

  • Maximum 1 GB per value.

  • Maximum 4 billion (> 2 KB) entries per table.

What Uses TOAST ​

  • bytea columns (raw bytes).

  • text columns (character data).

  • jsonb columns.

  • Any variable-length type that can exceed ~2 KB.