Interview Q&A / PostgreSQL

INTERVIEW Q&A · 69 QUESTIONS

PostgreSQL interview questions

Indexes, EXPLAIN, transactions and isolation, JSONB and the Postgres specifics backend interviews probe.

  1. What do MATERIALIZED and NOT MATERIALIZED do on a CTE?

    They control whether PostgreSQL computes the CTE once and stores the result (MATERIALIZED) or folds it into the outer query like a subquery (NOT MATERIALIZED). Before version 12, every CTE was materialized and acted as an optimisation fence.

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