Performance Difference Between 'select' And 'insert into..as select' For The Same Query
Last updated on SEPTEMBER 15, 2016
Applies to:Oracle Database - Enterprise Edition - Version 126.96.36.199.0 and later
Information in this document applies to any platform.
a) Select query runs fine and performance is as expected.
select .... from ....
b) When the same query is used in an 'insert into .. as select' statement the plan changes and performance is much slower.
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 :
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