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 the difference between Seq Scan, Index Scan and Bitmap Heap Scan in a PostgreSQL plan?
Seq Scan reads the whole table, Index Scan follows the index row by row, and Bitmap Heap Scan collects matching row locations from the index first, then reads table pages in physical order. The planner picks by estimated selectivity and cost.
BeginnerQuick answer1 min read