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#1 (**permalink**) 04-16-2008, 01:50 AM

Philippe Lang a écrit :
> Why don't you use tcpdump, or another sniffer, in order to check that, and post the result here?

Hi,

Sure !
Here are the two dumps.
http://tehwild.free.fr/divers/dumps.zip
One is a TCP dump of the query through pgAdmin, the other one
through psqlODBC.
The first obvious difference is that the window size is not the
same, but I don't know how to interpret that.

Regards
--
Arnaud

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#2 (**permalink**) 04-16-2008, 01:51 AM

Arnaud Lesauvage <thewild@freesurf.fr> writes:
>
> Sure !
> Here are the two dumps.
> http://tehwild.free.fr/divers/dumps.zip
> One is a TCP dump of the query through pgAdmin, the other one
> through psqlODBC.
> The first obvious difference is that the window size is not the same,
> but I don't know how to interpret that.

The best free tools I know to analyze such issues is tcptrace + xplot

<http://www.tcptrace.org/>

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#3 (**permalink**) 04-16-2008, 01:51 AM

You may try "ethereal" which can give you more details than the TCP
dumps with a structured view of packets and protocol layers.

Olivier.

Marc Herbert wrote:

>Arnaud Lesauvage <thewild@freesurf.fr> writes:
>
>
>>Sure !
>>Here are the two dumps.
>>http://tehwild.free.fr/divers/dumps.zip
>>One is a TCP dump of the query through pgAdmin, the other one
>>through psqlODBC.
>>The first obvious difference is that the window size is not the same,
>>but I don't know how to interpret that.
>>
>>
>
>The best free tools I know to analyze such issues is tcptrace + xplot
>
><http://www.tcptrace.org/>
>
>
>
>
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> match
>
>
>
>

#4 (**permalink**) 04-16-2008, 01:51 AM

O B a écrit :
> You may try "ethereal" which can give you more details than the TCP
> dumps with a structured view of packets and protocol layers.

The included dumps *are* ethereal dumps, actually.
There must be a reason why psqlODBC sets a different RWIN than the
other frontends (psql and pgAdmin), but I don't know which one.

Regards
--
Arnaud

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#5 (**permalink**) 04-16-2008, 01:51 AM

O B <ob@kselnet.com> writes:

> You may try "ethereal" which can give you more details than the TCP
> dumps with a structured view of packets and protocol layers.

ethereal is a great general-purpose tool but is not good at analyzing
TCP performance issues, because you only get numbers. With
tcptrace/xplot you get graphical timelines of sequence numbers and of
window sizes; I don't think ethereal can't match that. It's the same
difference between an excel spreadsheet and the corresponding graph.

Of course you have to be sure that your performance issue is somewhat
related to TCP parameters, else there is no need to go into tcptrace.

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