pg_plan_alternatives: Tracing PostgreSQL’s Query Plan Alternatives using eBPF

PostgreSQL uses a cost-based optimizer (CBO) to determine the best execution plan for a given query. The optimizer considers multiple alternative plans during the planning phase. Using the EXPLAIN command, a user can only inspect the chosen plan, but not the alternatives that were considered. To address this gap, I developed pg_plan_alternatives, a tool that uses eBPF to instrument the PostgreSQL…