My Oracle Support Banner

Complete Refresh of Materialized View Uses Nested Loops Instead of Hash Joins when Remote Objects Queried over DBLINK (Doc ID 2052843.1)

Last updated on NOVEMBER 07, 2023

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.4 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 Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.

Symptoms

 The complete refresh of a materialized view with many rows uses nested loops to refresh instead of hash joins.   The select statement itself uses hash joins.

Here is an example of an explain plan for the complete refresh.  Notice that the estimated cardinality is 1.

  

 

Cause

To view full details, sign in with your My Oracle Support account.

Don't have a My Oracle Support account? Click to get started!

In this Document
Symptoms
Cause
Solution
References


My Oracle Support provides customers with access to over a million knowledge articles and a vibrant support community of peers and Oracle experts.