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Data Dictionary View Queries are Slow - Potential Solutions (Doc ID 222671.1)

Last updated on SEPTEMBER 20, 2022

Applies to:

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


This article outlines the basic steps to take when queries against Data Dictionary Views


Prior to Oracle 10g, the data dictionary was optimized to use the Rule-Based Optimizer (RBO). By default the dictionary had no statistics and queries used RBO or CBO (Cost Based Optimizer) if hints were present in the underlying dictionary views. With large databases, this tended not to scale and so some queries against the data dictionary performed sub-optimally. 

In later releases, enhancements were made to improve the performance. This document outlines some of these and also available workarounds and their advantages and disadvantages in the case of problems.


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