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Subquery Factoring (WITH) Clause (Doc ID 1662498.1)

Last updated on JANUARY 23, 2020

Applies to:

Oracle Database - Enterprise Edition - Version 9.0.1.0 and later
Oracle Database Cloud Schema 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
Oracle Database Backup Service - Version N/A and later
Information in this document applies to any platform.

Purpose

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If similar subqueries appear more than once in a sql, it is worth trying to rewrite the query using WITH subquery.
There are some things we should consider in order to get the benefit from it.

Details

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In this Document
Purpose
Details
 Subquery Factoring
 Things to Consider when Deciding to Use Subquery Factoring
 Examples of Subquery Factoring
 Influencing the Plan with Hints and Parameters
 Hints
 Optimizer Parameter
 Demonstration
 Query 1 - Without Subquery Factoring
 Query 1 - With Subquery Factoring
 Query 2 - Without Subquery Factoring
 Query 2 - With Subquery Factoring
  Documentation
References

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