Slow Performance for Parallel Queries After Upgrading the Database to 126.96.36.199 or 188.8.131.52
Last updated on JUNE 12, 2017
Applies to:Oracle Database - Enterprise Edition - Version 184.108.40.206 to 220.127.116.11 [Release 11.2 to 12.1]
Information in this document applies to any platform.
- Application runs more slowly after having upgraded the database to 18.104.22.168 or 22.214.171.124.
- On analysis the performance of application jobs running parallel queries has become degraded and execution plan for these SQL statements have changed.
- Prior to 126.96.36.199, with parallelism enabled the SQL statements use Full Table Scan or Index Fast Full Scan.
- On 188.8.131.52 or 184.108.40.206, the execution plan changed from a Full Table Scan or Index Fast Full Scan to Index Full Scan.
- The index scans result in huge waits for 'db file sequential read' and the number of physical reads are higher due to table lookup following index rowid.
- Setting the OPTIMIZER_FEATURES_ENABLE to 220.127.116.11 does not help.
Database is upgraded to 18.104.22.168. or 22.214.171.124.
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