enable_nestloop

Inflates the cost of Nested Loop joins. Useful to verify whether a slow nested-loop plan was chosen because of a row-estimate mistake — if turning this off produces a fast hash/merge join, the planner's estimate is wrong.

Leave on. Off is for diagnosis only — nested loops are exactly the right join for some queries (small outer with indexed inner), and globally disabling them hurts those.

• Nested Loop Join
• Hash Join
• Merge Join

• enable_hashjoin
• enable_mergejoin