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Session-level optimizer parameter to disable Nested Loops joins

On a large data warehouse and when running non-interactive, batch jobs, nested loops joins are almost always a bad idea.

Most often, they result from an incorrect execution plan based on incorrect cardinality estimates, caused by incorrect and/or stale statistics.

There should be either a session-level or a system-level parameter (or both) to instruct the optimizer never to use a nested loops join, as if the NO_USE_NL hint was being used on every table in the SQL query.

William Robertson
1 votes

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