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 an expression index, and how do you make WHERE lower(email) = 'x' fast?
An expression index stores the result of a function or expression instead of the raw column. Create an index on lower(email) and queries that use exactly lower(email) can use it; a plain index on email cannot help.
BeginnerQuick answer1 min read