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Re: Connection function

From: Federico Di Gregorio <fog(at)dndg(dot)it>
To: psycopg(at)postgresql(dot)org
Subject: Re: Connection function
Date: 2012-03-26 07:52:02
Message-ID: 4F702022.5050109@dndg.it (view raw or flat)
Thread:
Lists: psycopg
On 25/03/12 17:14, Bill House wrote:
[snip]
> Sometimes it is helpful to know how many records one is working with.
>
>  From my reading in the psycopg2 documentation (2.4.4) and
> experimentation, I think that this information is only available if one
> uses an unnamed cursor (in which case all the data will have been
> fetched to the client) or with an named cursor (but only after all the
> data has been fetched).
>
> If there is a large amount of data, this may be problematic.

Not at all. You just need to MOVE to the end of the result set and count 
how many rows you skipped. At the moment psycopg doesn't use MOVE return 
value (that tells you what you want to know) but can just .execute() the 
MOVE and access the result on the cursor. Also, we could probably extend 
scroll() to return the number of scrolled rows in the future.

> In particular, I am interested in:
>      1) the python string substitution technique I used

Use bound parameters:

http://packages.python.org/psycopg2/usage.html#query-parameters

federico

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