Re: Sniffer to trace ODBC calls?

I have made some tests with very simple filters, like "param = 123", and filtering happens server-side all the time. I wonder is there could be a more complicated combination of criterias that would cause a filtering client-side, like with a Jet database backend? I don't think so...

Philippe

-----Message d'origine-----
De : pgsql-odbc-owner(at)postgresql(dot)org
[mailto:pgsql-odbc-owner(at)postgresql(dot)org]De la part de Philippe Lang
Envoyé : mercredi, 10. décembre 2003 08:39
À : Pgsql-Odbc (E-Mail)
Cc : Benjamin Riefenstahl
Objet : Re: [ODBC] Sniffer to trace ODBC calls?

Hello,

When an access database has linked tables with another MDB on the network, you can easily have situations where filtering is actually made client-side. All records are fetched from the network, and then only those that match the criteria appear on the screen.

Now, I still have linked tables, but through ODBC, and a postgresql backend. I agree this is not the same, and filtering is likely to occur server-side, but I just wanted to make sure with an SQL Sniffer. I don't know exactly how access exactly filters data.

I'll check that today...

Philippe

-----Message d'origine-----
De : Benjamin Riefenstahl [mailto:Benjamin(dot)Riefenstahl(at)epost(dot)de]
Envoyé : mardi, 9. décembre 2003 19:36
À : Philippe Lang
Cc : Pgsql-Odbc (E-Mail)
Objet : Re: Sniffer to trace ODBC calls?

Hi Philippe,

"Philippe Lang" <philippe(dot)lang(at)attiksystem(dot)ch> writes:

> I'm opening Access forms with a filter, and I'd like to know where
> the filtering is actually taking place: on the server, or on the
> client?

AFAIK ODBC itself doesn't do *anything* except forward your calls to
the ODBC driver and probably some repackaging to support outdated
driver versions with comptibility code.

So where do you think the filtering may take place? In the database
ODBC driver? That wouldn't make sense. If the database vendor can do
the filtering in the driver, it can just as well do it on the server.

In Access? Than the ODBC trace will tell you. If Access does the
filtering itself, the SQL queries will have no filtering clauses. If
Access doesn't do filtering itself but asks the server, the SQL
statements will contain WHERE clauses to do it.

benny

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