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Query with Analytic Windowing Function, Such as ROW_NUMBER OVER PARTITION BY, is Slower in Release 12.1.0.2 (Doc ID 2118138.1)

Last updated on FEBRUARY 18, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 12.1.0.2 and later
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud 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
Information in this document applies to any platform.

Symptoms

On 12.1.0.2, a query containing an analytic windowing function (such as ROW_NUMBER () OVER PARTITION BY) is performing poorly.  Following is an example:

Notice how the cardinality estimate at line one has changed from one to 77,330.

Changes

There may have been a recent upgrade to Oracle Database Release 12.1.0.2.  The performance of the query is worse now than it was on the prior release.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References


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