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 does it mean when estimated rows and actual rows differ a lot in EXPLAIN ANALYZE?
The planner chose its plan from a wrong guess about row counts. Usual causes are stale statistics, correlated columns, or expressions it cannot estimate. Run ANALYZE, raise the statistics target, or create extended statistics.
IntermediateQuick answer1 min read