Poor Performance for Query with ROWNUM predicate and NESTED LOOPS.
Last updated on JANUARY 25, 2018
Applies to:Oracle Database - Enterprise Edition - Version 22.214.171.124 to 126.96.36.199 [Release 11.1]
Information in this document applies to any platform.
- Queries which include a ROWNUM predicate may get a suboptimal plan, typically including an expensive NESTED LOOPS join.
- Explain plan shows a join to a subquery or view which has incorrectly assumed that the cardinality returned will be that of the rownum predicate.
- Users might see a nested loop join in the plan when the query has a rownum predicate and contains a view.
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