Query is Slow, Explain Plan Shows "MERGE JOIN CARTESIAN" Operation Which is Taking Most of the Time
(Doc ID 2032840.1)
Last updated on AUGUST 04, 2018
Oracle Database - Enterprise Edition - Version 10.2.0.5 and later Information in this document applies to any platform.
Query performs slowly: this can manifest in a number of different ways dependent on the environment and the amount of data involved (e.g. high memory and temporary table usage, high CPU etc. )
Execution plan shows that a MERGE JOIN CARTESIAN operation is involved:
All the objects in the query are joined to one of the other objects - there are no missing joins
The MERGE JOIN CARTESIAN operation is taking most of the time in the query or sparks off slow activity in the following steps.
The row counts for the MERGE JOIN CARTESIAN operation bear no relationship with reality. For example, the E-Rows for the MERGE JOIN CARTESIAN operation are inaccurate compared to the real number of rows that these steps involve.
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