Re: Improve ODBC Throughput ?

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От Ludek Finstrle
Тема Re: Improve ODBC Throughput ?
Дата
Msg-id 20061020091152.GC29380@soptik.pzkagis.cz
обсуждение исходный текст
Ответ на Re: Improve ODBC Throughput ?  (Arnaud Lesauvage <thewild@freesurf.fr>)
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Hello,

> >UseDeclareFetch and UseServerSidePrepare are disjoint options.
> >If I remember it the right way the UseServerSidePrepare disallow
> >UseDeclareFetch. Please try UseServerSidePrepare=0 when you want
> >using DeclareFetch.
> >
> >Why you set Fetch so high? How many rows do you expect?
> >The UseDeclareFetch declare the select statement as cursor (using
> >declare statement) and then get the rows using fetch statement
> >(see postgresql manual).
> >I see no usage for UseDeclareFetch with so high Fetch.
> >
> >The UseServerSidePrepare use prepare and execute statement (also
> >see postgresql manual).
>
> I thought that since memory consumption was not an issue, I
> could fetch a lot of rows at once. I read the ODBC

Yes, it could. When you have UseDeclareFetch=0 it get all rows at once.
But sometimes it take too long when you need few of them ASAP and
others later (so it's good time to use UseDeclareFetch=1).

> documentation about that but not PostgreSQL's, but I'll
> correct this ASAP.

That's no problem. I only point you to the documentation to fully
understand what psqlODBC makes for you internally ;o) It's always
the good start point when you need some tuning.
BTW the start reference point is:
http://www.postgresql.org/docs/8.1/interactive/sql-commands.html

> What is your advice in fact ?

I don't know what you really want. Sometimes is better UseDeclareFetch=1,
sometimes is better UseServerSidePrepare=1 and sometimes is better
UseDeclareFetch=0 and UseServerSidePrepare=0.

I don't know how internally works Access or CAD so I have no advice.

Regards,

Luf

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