Re: bad performance with a simple select statement
Keep in mind that activating PDQ (Parallel Database Query) parameter forces
informix to do sequential scan with hash join. Of course before turning the
PDQ parameter off (if activated), try other advises.
Gursoy YERLI
lol007@my-dejanews.com wrote:
> Hello:
> I run INFORMIX-Universal Server Version 9.14.UC1X3 on a SGI/IRIX 6.2 INDY
> RS5000SC box.
> I create a buffered-logging database in a mirrored dbspace.
> I create the following table :
> create table test (
> f1 int,
> f2 smallfloat,
> f3 smallfloat,
> f4 smallfloat,
> f5 smallfloat,
> f6 smallfloat,
> f7 smallfloat,
> f8 smallfloat,
> f9 smallfloat,
> f10 smallfloat,
> PRIMARY KEY (f1)
> );> I load the table with a 400K records file.
> The following simple statement :
> select * from test where f1=200000;> takes 10 seconds !?
>
> I even tried the following :
> begin work;
> set isolation to dirty read;> select {+ USE_INDEX(test,100_1) } * from test where f1=1;
> commit work;
> Still 10" long !
>
> The same query on MS SQL 6.5 is almost instantaneous ... :-(
>
> Any idea ?
> LL
>
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