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A query has FROM orders o JOIN customers c ON o.customer_id = c.id. The planner can choose between hash join, merge join, and nested loop. Which is typically chosen for two large tables with no indexes on the join keys?

Nested loop (slowest)Hash join — builds an in-memory hash of one table and probes from the other; usually fastest for large unsorted joins without supporting indexesMerge join — but only if both sides are pre-sortedIndex scan