CREATE INDEX CONCURRENTLY: Building Indexes Online
A normal CREATE INDEX quietly blocks every INSERT, UPDATE, and DELETE on the table until it finishes, which on a large table can mean minutes of frozen writes.
CREATE INDEX CONCURRENTLY builds the same index while writes keep flowing. It trades a little extra time and care for staying online.
Pro members see the rest of this lesson
- A 4-step state diagram: Announce → Build → Wait → Validate
- The full mechanism: what PostgreSQL does internally, in source terms
- 3 SQL queries you can run, each labelled by how it was verified
- 3 transcripts captured on PostgreSQL 17.10
- The closing insight, the mistake it prevents, and what it changes in your work
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Check it against the source1 citation in postgres/postgres · file, symbol and line verified on REL_17_STABLE
Primary symbol: DefineIndex · line 540
Anchored to postgres/postgres on REL_17_STABLE and cross-checked against the manual for PostgreSQL 15–18. Every query here was run and its output captured on a throwaway PostgreSQL 17.10 lab; corrections are noted inline. CREATE INDEX (CONCURRENTLY) in the official docs →
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