[Qt-interest] QODBC seems very slow connecting to MSSQL

[Bill King]

 On 07/13/2010 06:08 PM, ext Christian Dähn wrote:
> Hi,
>
> I used the TDS sql driver from Qt up to this year for a big MS SQL
> Server 2005 with many
> connections / queries per second. The funny thing is: everybody claims
> TDS to be dead already,
> but there's no alternative to this native client.
>
> ODBC is and stays much slower than TDS and: I had to move to QODBC due
> to the dropped
> support by Qt (I've patched the QTDS massively for SQL Server 2005 -
> so, if anybody needs
> an up to date QTDS driver: ask me).
Please feel free to make merge requests on gitorious. They will be
gladly accepted.
>
> If you have slow QODBC connections/queries, check out this:
> a) is the tracing / logging for ODBC enabled? then turn it off.
> b) are your queries quite complex? do you have sufficient indexes?
> c) did you set QSqlQuery::setForwardOnly(TRUE) before executing your
> query?
>
> The setForwardOnly() should be set (by my experience) always to TRUE
> for all MS SQL Servers -
> otherwise the query results are fetched as single rows from the
> database which slows down
> your queries by factor 100 ore more.
>
> Example:
> I had a big client database and requested a result set of clients with
> only 100 entries.
> Due to the setForwardOnly(false) (which is Qt's default), the QODBC
> asked the database
> (a MS SQL Server 2008) exactly 100 times for the next result (row) -
> this took me up to 800 ms!
> When I turned on the forward only mode, I got all 100 rows as one
> reply - in only 25 ms!
>
> ciao,
> Chris
>
>
> Am Di 06.07.2010 11:13 schrieb Harry Sfougaris <hsfougaris at gmail.com>:
>
> > > Unfortunatly TDS doesn't support latest versions of MSSQL server (and
> > > it looks like project is dead or almost dead).
> > Looking at the FreeTDS mailing list it doesn't look that dead as
> everyone makes it out to be.
> > And of course it supports all version of MSSQL server; it just
> doesn't support some very fancy new options
> >
> > > And more sadly thing is that TDS is the only MSSQL driver for
> other platforms than windows...
> > I think that is exactly the issue here. People claim TDS is dead so
> we should use ODBC, but all ODBC drivers (outside Windows) is based on
> TDS anyway....
> > If TDS really dies, so will all the ODBC drivers. Meanwhile, we are
> stuck with inefficient access to one of the world's most popular DBMS
> (unfortunately)...
> >
> > Harry
> >
> > >
> > >
> > > 2010/7/5 Harry Sfougaris <hsfougaris at gmail.com>:
> > >>
> > >> On 5 ???? 2010, at 20:42, "Scott Aron Bloom"
> <Scott.Bloom at onshorecs.com> wrote:
> > >>
> > >>> The TDS system is very old, and much slower than the ODBC
> connection...
> > >>
> > >> I think this statement is only accurate when running under Windows.
> > >> All ODBC drivers I have seen under Mac and Linux are based on TDS.
> > >>
> > >> And I agree odbc is slower than tds even under windows.
> > >> It was very sad for me to see Qt dropping support for it, thus
> leaving no decent support for MSSQL when not running under windows.
> > >>
> > >> Harry
> > >>
> > >>
> > >>>
> > >>> Read about its problems here.
> > >>>
> > >>> http://labs.trolltech.com/blogs/2010/02/09/tds-driver-deprecation/
> > >>>
> > >>> Scott
> > >>>
> > >>> -----Original Message-----
> > >>> From: qt-interest-bounces at trolltech.com
> > >>> [mailto:qt-interest-bounces at trolltech.com] On Behalf Of Stephen
> Jackson
> > >>> Sent: Monday, July 05, 2010 10:15 AM
> > >>> To: Qt-interest
> > >>> Subject: Re: [Qt-interest] QODBC seems very slow connecting to MSSQL
> > >>>
> > >>> On 5 July 2010 12:53, Roland Tollenaar wrote:
> > >>>>
> > >>>> We seem to experience that using QODBC with QSqlQuery can be rather
> > >>> slow
> > >>>> when used with MSSQL.
> > >>>>
> > >>>> Is there a native plugin for mssql that is faster?
> > >>>>
> > >>>> We are using Qt 4.5.2.
> > >>>>
> > >>>> Thanks in advance,
> > >>>>
> > >>>
> > >>> The native driver is TDS
> > >>>
> > >>> qt/src/sql/drivers/tds
> > >>>
> > >>> However, I don't know how it performs compared to ODBC.
> > >>>
> > >>> --
> > >>>
> > >>> Stephen Jackson
> > >>> _______________________________________________
> > >>> Qt-interest mailing list
> > >>> Qt-interest at trolltech.com
> > >>> http://lists.trolltech.com/mailman/listinfo/qt-interest
> > >>>
> > >>> _______________________________________________
> > >>> Qt-interest mailing list
> > >>> Qt-interest at trolltech.com
> > >>> http://lists.trolltech.com/mailman/listinfo/qt-interest
> > >>
> > >> _______________________________________________
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> > >>
> > >
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> >
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>
>
> Mit freundlichen Grüssen,
> Christian Dähn
> Consultant
>
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-- 
Bill King, Software Engineer
Qt Development Frameworks, Nokia Pty Ltd
Brisbane Office