Date: 2026-05-20
Time: 15:30–15:55
Room: Canfor
Level: Intermediate
How does PostgreSQL actually handle EXISTS and IN clauses? This talk explores the internals of Semi-Join optimization, comparing the native JOIN_SEMI execution against the strategy of unique-ifying the right-hand side. We will discuss the implications of these strategies on join reordering and query performance. We will also cover some evolutions regarding semi-join planning in recent releases.