Re: Slow query through ODBC

> Magnus Hagander a écrit :
> > Since it works with different speeds in different clients, it 
> > *probably* isn't on the server side. I'm far from sure on 
> that though, 
> > there may be other paramters that are implicitly changed 
> when ODBC is used.
> 
> Yes, that was my first impression also. But the fact that the 
> server waits for an ACK from the client before it goes on 
> sending packet is quite strange, isn't it ?

Yes. Most definitly.


> > It's interesting to note that your problem is with a single 
> large field.
> > If you query for approximatly the same amount of data *but 
> in several 
> > small fields*, do you get the same behaviour? Or does it 
> happen only 
> > with large fields?
> 
> I have splitted the data into 4 fields.
> The largest field was ~23.000 characters long, so I made 4 
> fields containing. The first one contains the first 6000, the 
> second one from 6001 to 12000, etc...
> The query took about half the time to run !

Interesting. Did it make any difference to the timings in psql and/or pgadmin?


> > We enable TCP_NODELAY on both server and client, when 
> available. And 
> > it is available - I've double-checked and that code is 
> indeed compiled 
> > into both libpq and the server on 8.1 at least.
> 
> I run 8.1.2, so I assume that it is enabled on my workstation 
> and on the server.

Yup.


> > But I don't see how this can make a difference between pgadmin and 
> > odbc and psql, since they all use the same code!
> 
> Yes, I really don't understand either !
> But even though all use libpq.dll, they might not handle the 
> data the same way. Mayboe ODBC needs to check for data type, 
> field length, etc... and the other frontends do not need this 
> kind of information ?

Hm. That's an interesting observation. When you do a query with ODBC, does it do any "extra queries" automatically on the system tables? Enable statement logging on the server and see if something weird shows up.

//Magnus