After Upgrade to 12c from 11g, Query Uses Nested Loop Instead Of Merge Join, Causing Slow Performance
(Doc ID 2250039.1)
Last updated on JANUARY 15, 2019
Applies to:
Oracle Database - Enterprise Edition - Version 12.1.0.2 and laterOracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
- After upgrading our database from 11.2.0.4 to 12.1.0.2, sql is not using merge join anymore, instead it uses nested loop and the script runs forever
Changes
Upgraded from 11.2.0.4 to 12.1.0.2
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |