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Re: 500 times slower

From: "Dave Page" <dpage(at)vale-housing(dot)co(dot)uk>
To: "Karol Szkudlarek" <karol(at)mikronika(dot)com(dot)pl>
Cc: <pgsql-odbc(at)postgresql(dot)org>
Subject: Re: 500 times slower
Date: 2005-02-09 13:17:17
Message-ID: E7F85A1B5FF8D44C8A1AF6885BC9A0E45289FE@ratbert.vale-housing.co.uk (view raw or flat)
Thread:
Lists: pgsql-odbc
 

> -----Original Message-----
> From: pgsql-odbc-owner(at)postgresql(dot)org 
> [mailto:pgsql-odbc-owner(at)postgresql(dot)org] On Behalf Of Karol Szkudlarek
> Sent: 09 February 2005 11:48
> To: Karol Szkudlarek
> Cc: pgsql-odbc(at)postgresql(dot)org
> Subject: Re: [ODBC] 500 times slower
> 
> Karol Szkudlarek wrote:
> > 
> > The problem exists only between windows client and remote windows 
> > server. The other configurations (for example remote linux server)
> > works ok. We are using stable version of psqlodbc driver.
> > 
> > ---------------------------(end of 
> broadcast)---------------------------
> > TIP 7: don't forget to increase your free space map settings
> 
> Hi!
> 
> My collegue spent some time to dig the following case and it 
> looks like 
> Nagle algorithm and delayed ACKs related problem.
> In psqlodbc.h
> #define SOCK_BUFFER_SIZE			4096
> 
> I changed that value to 8192 and driver works fine for me.
> I am not sure why this change helps.

Err, no neither am I. Why do you think it's got something to do with
Nagle/delayed ACKs?

The only thing that instantly rings bells for me is that the max size of
a text field is 8190 bytes at present (which really should be increased,
if not removed altogether), which won't fit in the default buffer. But
then, I wouldn't expect to see the performance drop you describe with a
4096 byte buffer, only one much smaller.

Anyone else got any ideas?

Regards, Dave

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