The PostgreSQL Query Planner

Robert Haas

Why does my query need a plan? Sequential scan vs. index scan. Join strategies. Join reordering. Joins you can't reorder. Join removal. Aggregates and DISTINCT. Using EXPLAIN. Row count and cost estimation. Things the query planner doesn't understand. Other ways the planner can fail. Parameters you can tune. Things that are nearly always slow. Redesigning your schema. Upcoming features and future work.

The PostgreSQL Query Planner.odp293.67 KB