Change In Plans With Different Statistics Collection Method For Function Based Index (Doc ID 458076.1)

Last updated on SEPTEMBER 15, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 8.1.7.0 to 10.2.0.1 [Release 8.1.7 to 10.2]
Information in this document applies to any platform.
This problem can occur on any platform.

Symptoms

Table has a function based index. Query on this table goes for an Index Range scan when statistics are gathered at table level with cascade as TRUE. However, if the index is dropped and recreated and only index stats gathered this time, query goes for Full Table Scan.

The issue can be illustrated as follows:

Create table, index and gather statistics on both:

 

Cause

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