Interview Q&A / PostgreSQL
PostgreSQL interview questions
Indexes, EXPLAIN, transactions and isolation, JSONB and the Postgres specifics backend interviews probe.
Prefer rapid revision? Practise PostgreSQL short interview answers →
- What is the difference between SERIAL and IDENTITY columns, and when would you use a UUID primary key?
SERIAL is an older PostgreSQL shorthand that creates a sequence and sets it as the column default. IDENTITY (GENERATED ALWAYS or BY DEFAULT AS IDENTITY) is the SQL-standard replacement and is preferred for new tables. Use a UUID when IDs must be generated outside the database, merged across systems, or must not be guessable.
BeginnerIn-depth3 min read - How do you generate and store UUIDs in PostgreSQL?
Use the uuid type, which stores 16 bytes, and generate values with the built-in gen_random_uuid() (available without an extension since PostgreSQL 13). Store them as uuid, not as 36-character text.
BeginnerQuick answer1 min read