TLDR Tech / Data
HOT Updates in Postgres
HOT Updates in PostgreSQL is a clever storage optimization that allows UPDATEs on unindexed columns to avoid touching indexes entirely when the new tuple fits on the same page as the old one. Instead of creating new index entries, PostgreSQL marks the old tuple as HOT_UPDATED and places a HEAP_ONLY tuple on the same page, forming a chain that scans can follow, which reduces WAL traffic, index maintenance, and vacuuming overhead.
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