Interview Q&A / PostgreSQL
PostgreSQL interview questions
Indexes, EXPLAIN, transactions and isolation, JSONB and the Postgres specifics backend interviews probe.
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- Why can a quick ALTER TABLE freeze every query on a busy table?
ALTER TABLE needs a strong lock that waits behind any running query on the table, and every new query then queues behind the ALTER. One long transaction can therefore stall the entire table. Set lock_timeout so the DDL gives up quickly.
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