Performance Difference Between 'select' And 'insert into..as select' For The Same Query (Doc ID 1303570.1)

Last updated on SEPTEMBER 15, 2016

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.2.0 and later
Information in this document applies to any platform.

Symptoms

a) Select query runs fine and performance is as expected.
Example:
   select .... from ....

b) When the same query is used in an 'insert into .. as select' statement the plan changes and performance is much slower.
Example:
   insert  into table ... as select ... from ....

Change noticed in the plans of 'select' compared to the 'insert into ... as select' :

1. The select used Bloom Filters while the 'insert into .. as  select' does not use Bloom Filters:

- In the name column of the explain plan you will see references like the following which indicate the use of Bloom Filters :

     :BF0000

Changes

None

Cause

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