Markus Winand's "Use The Index, Luke" site is the classic reference. It covers most of the major DBs, but also gets into PG specifics. https://use-the-index-lu

Markus Winand's "Use The Index, Luke" site is the classic reference. It covers most of the major DBs, but also gets into PG specifics. https://use-the-index-luke.com/sql/explain-plan/postgresql/operations https://use-the-index-luke.com/sql/explain-plan/postgresql/o... Understanding query plans is a universal skill that mostly transcends database particulars, so even this Planetscale article will serve as a good primer too.