Queries Using ANSI Joins Run Slow In 12C
Last updated on MARCH 01, 2018
Applies to:Oracle Database - Standard Edition - Version 220.127.116.11 and later
Information in this document applies to any platform.
- After upgrading the database to 12c, the queries using ANSI joins are running slower.
- The same SQLs used to run faster in pre-12c environment.
- Optimizer chooses inefficient plan in 12c for SQLs having ANSI joins and scalar subqueries.
- The non-ANSI version of the same SQLs run fine even in 12c environment.
- Setting OPTIMIZER_FEATURES_ENABLE = 18.104.22.168 gives the good plan and resolves the problem.
Upgrading to 12c including 12.2 and 18.1.
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