Interview Q&A / PostgreSQL
PostgreSQL interview questions
Indexes, EXPLAIN, transactions and isolation, JSONB and the Postgres specifics backend interviews probe.
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- How does a recursive CTE work? Show one that counts from 1 to 5.
A recursive CTE has an anchor query that produces the starting rows and a recursive query that refers to the CTE itself, joined with UNION or UNION ALL. PostgreSQL repeats the recursive step on the latest rows until it returns nothing.
BeginnerQuick answer1 min read - What is a CTE (WITH clause) and why would you use one?
A common table expression names a subquery at the top of a statement so you can read it in steps and reuse it more than once. It improves readability; since PostgreSQL 12 a simple CTE is usually inlined like a subquery.
BeginnerQuick answer1 min read