Interview Q&A / PostgreSQL
PostgreSQL interview questions
Indexes, EXPLAIN, transactions and isolation, JSONB and the Postgres specifics backend interviews probe.
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- What is a covering index and what does the INCLUDE clause do?
A covering index holds every column a query needs, so PostgreSQL can answer from the index alone with an index-only scan. INCLUDE adds extra payload columns to the index leaf without making them part of the sort key or uniqueness.
IntermediateQuick answer1 min read