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Date: Thu, 16 Jul 1998 11:41:47 +0300
From: Hannu Krosing <hannu@trust.ee>
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To: Bruce Momjian <maillist@candle.pha.pa.us>
CC: David Hartwig <daveh@insightdist.com>, pgsql-interfaces@postgreSQL.org,
	hackers@postgreSQL.org
Subject: Re: [INTERFACES] Re: [HACKERS] changes in 6.4
References: <199807152339.TAA07145@candle.pha.pa.us>
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Bruce Momjian wrote:
> 
> > The results are profound.    Queries that used to scan tables because of the
> 
> How about if instead of doing:
> 
>         select * from tab1 where val = 3
>         union
>         select * from tab1 where val = 4
>         ...
> 
> you change it to:
> 
>         select * from tab1 where val in (
>                 select 3
>                 union
>                 select 4
>         )
> 

the explosion happens for ORs of multiple ANDs that get rewritten to:

select * from tabl wehere val1=1 and val2=1 and val3=1
union
select * from tabl wehere val1=1 and val2=1 and val3=2
union
...


And there is no way of doing (at least presently):

select * from table where (val1,val2,val3) in (select 1,1,1 union select
1,1,2);

Hannu