Change In Plans With Different Statistics Collection Method For Function Based Index
Last updated on SEPTEMBER 15, 2016
Applies to:Oracle Database - Enterprise Edition - Version 188.8.131.52 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.
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:
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