Re: JT400/JDBC performance issues

[Dieter.Bender@xxxxxxxxxxx]

Hi Mark,

where did you here this, that might have been true many years ago.
Today there is not any problem using views.

Dieter

Mark Phippard schrieb:
> Dieter,
> 
> >> To get performance that bad it seems like it would
> have to have 
> something
> >> to do with the JDBC statements you are executing.  Are
> you using SQL 
> Views
> >> in your SELECT?  Generally, these perform worse than
> Tables on the 
> iSeries.
> >
> > the diffrence is less than 0,1 sec
> 
> I will admit that I have never measured it and we only
> use Tables in our 
> statements.  I am basing this on statements I have seen
> elsewhere that 
> said when you use a View, the query optimizer is not able
> to take into 
> account the indexes that are over the table and in some
> cases this will 
> yield significantly worse performance.
> 
> Mark
> 
> 
> 
> 
> 
> 
> 
> Dieter.Bender@xxxxxxxxxxx (Dieter Bender)
> Sent by: java400-l-bounces@xxxxxxxxxxxx
> 02/19/2003 04:48 AM
> Please respond to Java Programming on and around the
> iSeries / AS400 
>  
>         To:     Java Programming on and around the
> iSeries / AS400 
> <java400-l@xxxxxxxxxxxx>
>         cc: 
>         Subject:        Re: JT400/JDBC performance
> issues
> 
> 
> Mark,
> 
> On Wednesday 19 February 2003 02:23, you wrote:
> > Suresh,
> >
> > To get performance that bad it seems like it would have
> to have 
> something
> > to do with the JDBC statements you are executing.  Are
> you using SQL 
> Views
> > in your SELECT?  Generally, these perform worse than
> Tables on the 
> iSeries.
> 
> the diffrence is less than 0,1 sec
> 
> >
> > You do not mention how large your tables are or how
> many records you are
> > selecting.
> >
> > Finally, once those issues are worked out, a big area
> where problems 
> will
> > occur with the iSeries is if you do not use Connection
> Pools. 
> Establishing
> > a connection to the iSeries has a high overhead.  Using
> a pool 
> eliminates
> > that problem.  However, we are talking seconds not
> minutes.
> 
> I've made measures on this, normally a connect shoul be <
> 0,3 sec and 
> making 
> 800 connections to a little 270 should not be a problem.
> 
> You should use connection pooling anyway, its easier to
> use for 
> transaction 
> handling and talking about web applications, you never
> know how many users 
> 
> wil connect, but in this case you won't see any
> improvement.
> 
> Dieter
> 
> >
> > Hope this helps,
> >
> > Mark
> >
> >
> > _______________________________________________
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> -- 
> mfG
> 
> Dieter Bender
> 
> 
> DV-Beratung Dieter Bender
> Wetzlarerstr. 25
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