Using Case Insensitive Searches and Setting NLS_SORT to Anything Other than BINARY (e.g. BINARY_CI) with NLS_COMP set to ANSI or LINGUISTIC Causes Full Table Scans Instead of Using Indexes
(Doc ID 2008186.1)
Last updated on MAY 19, 2022
Applies to:
Oracle Database - Enterprise Edition - Version 11.1.0.6 and laterOracle Database Cloud Schema Service - Version N/A and later
Gen 1 Exadata Cloud at Customer (Oracle Exadata Database 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
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- Queries are performing more slowly following the introduction of case insensitive searches (in this case using NLS_SORT=BINARY_CI) in the database
- With NLS_SORT set to anything other than BINARY (here NLS_SORT=BINARY_CI), queries are perform full table scans and ignore index based searches.
- NLS_COMP is set to ANSI or LINGUISTIC
Changes
Cause
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In this Document
| Symptoms |
| Changes |
| Cause |
| Solution |
| References |