Re: Input and Output data traffic - Mailing list psycopg

From Karsten Hilbert
Subject Re: Input and Output data traffic
Date
Msg-id 20110511114322.GI6613@hermes.hilbert.loc
Whole thread Raw
In response to Input and Output data traffic  (Israel Ben Guilherme Fonseca <israel.bgf@gmail.com>)
Responses Re: Input and Output data traffic  (Israel Ben Guilherme Fonseca <israel.bgf@gmail.com>)
List psycopg
On Wed, May 11, 2011 at 08:18:40AM -0300, Israel Ben Guilherme Fonseca wrote:

> LOL, sorry I wasn't explicit in my text. But i did the same test with
> psycopg2 too. :P

:-)       That makes better sense now.

> "For simple inserts/updates/deletes i got a difference of about 15% between
> sent and received data."

...

> If someone could say: "well, sent/received data should be significantly
> different and there is something wrong there", or "no it's normal". That
> would be helpful.

It very much depends on the exact queries used:

    1) INSERT INTO my_table (a, b) VALUES (1, 2);

    2) INSERT INTO my_table (a, b) VALUES (1, 2) RETURNING a, b;

I would expect a lot more data to be returned with 2) than
with 1).

(That difference in testing setup does not explain the
differences between drivers, though, if one assumes you've
been using the very same queries with each.)

The other thing is that one driver may be using server-side
cursors while another driver will use client-side cursors.
The latter will transfer a lot more data.

I think you'd have to be more specific about the exact
testing methodology to get useful advice.

Karsten
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