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 are the three join algorithms in PostgreSQL and when does the planner choose each?
Nested Loop probes the inner side once per outer row and suits small inputs or indexed lookups. Hash Join builds a hash table of one side and suits large unsorted equality joins. Merge Join walks two sorted inputs and suits large sorted ones.
IntermediateQuick answer1 min read