Обсуждение: Bad performance using ODBC

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Bad performance using ODBC

От
Albert Cervera Areny
Дата:
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Hi,
  I have a performance problem using postgresql when the connection is made
via ODBC with a windows machine using the latests ODBC drivers (Windows) and
PostgreSQL 7.3.3 (Linux).

  The queries made by my Visual Basic program are very very simple. It queries
with as Select if a record exists and if so, it reduces stock with an Update.
For the benchmarks I do it 200 times.

  If I test it against an Access database (located in a SMB server) it spends
3 seconds but against PostgreSQL 17 !! Exactly the same test programmed in C
(with pgsql libraries) and run within the same machine or another Linux
spends less than a second!!

  So the problem seems to be whether with the ODBC drivers or with Windows
ODBC itself. Are there any parameters in the ODBC drivers that might help
reducing that big overhead added or do you have any suggestions to speed it
up?

Thanks in advance!
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Re: Bad performance using ODBC

От
Tom Lane
Дата:
Albert Cervera Areny <albertca@jazzfree.com> writes:
>   I have a performance problem using postgresql when the connection is made
> via ODBC with a windows machine using the latests ODBC drivers (Windows) and
> PostgreSQL 7.3.3 (Linux).

Do you have logging turned on in the ODBC driver?  I recall hearing that
that adds a heck of a lot of overhead...

            regards, tom lane

Re: [ODBC] Bad performance using ODBC

От
Albert Cervera Areny
Дата:
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A Dimecres 16 Juliol 2003 16:38, Tom Lane va escriure:
> Albert Cervera Areny <albertca@jazzfree.com> writes:
> >   I have a performance problem using postgresql when the connection is
> > made via ODBC with a windows machine using the latests ODBC drivers
> > (Windows) and PostgreSQL 7.3.3 (Linux).
>
> Do you have logging turned on in the ODBC driver?  I recall hearing that
> that adds a heck of a lot of overhead...

After trying too many things I've finally been able to make it run in just 1
or 2 seconds. I simply had to change the recordset type and set it to
dbOpenSnapshot (This one doesn't show changes made to the database once it's
been open) instead of the default dbDynaset (much more powerful but
unnecessary in this application).

Take note that though it might seem obvious the performance loss against
Access isn't that much and thus VB users aren't probably used to change the
recordset type. I think It would be nice a note with this performance
benchmarks (2 seconds against 15) in the Mini-Howto on Accessing PostgreSQL
from Visual Basic. I'll contact Dave Page directly in case he finds it
interesting.

I haven't seen any speed improvements desabling logging but thanks for your
suggestion anyway!

>
>             regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 7: don't forget to increase your free space map settings
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