Subject Re: [firebird-support] Re: FB 2.5.4 - new handling of IN SUBSELECT?
Author Josef_Koke=c5=a1
On 5.11.2015 13:25, Dmitry Yemanov dimitr@...
[firebird-support] wrote:
>
> 05.11.2015 14:12, Josef KokeŇ° j.kokes@... wrote:
> >
> > I wonder: Was there any change in FB 2.5.4 which would slow down
> > processing of WHERE field IN (subselect) a lot, compared to FB 2.5.3? I
> > have been performing tests because a user of mine complained about slow
> > speed of my database, and found out that my query in the form of:
> >
> > SELECT COUNT(*)
> > FROM a_complex_view
> > WHERE field1=1 AND field2<>2
> > AND key_field IN (SELECT key_field FROM key_field_list)
> >
> > went from 2 seconds in FB 2.5.0-2.5.3 to 4 minutes in FB 2.5.4.
>
> What is execution plan for v2.5.3 and v2.5.4? Also worth trying a v2.5.5
> snapshot.
>

Hi Dmitry,

the execution plans were exactly the same (diff) for all tested
versions: a long chain of PLAN JOIN (JOIN (... INDEX (name1)) INDEX
(name2)).

I will see about 2.5.5 how it performs.

Josef