Re: libpq, PQexecPrepared, data size sent to FE vs. FETCH_COUNT

From: Yeb Havinga <yebhavinga(at)gmail(dot)com>
To: Alex Goncharov <alex-goncharov(at)comcast(dot)net>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: libpq, PQexecPrepared, data size sent to FE vs. FETCH_COUNT
Date: 2010-05-25 12:08:51
Message-ID: 4BFBBDD3.5070509@gmail.com
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Alex Goncharov wrote:
> ,--- I/Alex (Mon, 24 May 2010 12:25:18 -0400) ----*
> | No equivalent of FETCH_COUNT is available at the libpq level, so I
> | assume that the interface I am using is smart enough not to send
> | gigabytes of data to FE.
> |
> | Where does the result set (GBs of data) reside after I call
> | PQexecPrepared? On BE, I hope?
>
> Sorry for asking again...
>
> No sarcasm meant: is there no straightforward answer here? Or nobody
> is certain? Or a wrong list?
>
The straighforward answer is that the libpq frontend c-library does not
support something like the JDBC client's setFetchSize.

The GBs of data are gathered at the site of the libpq client (pgresult
object gathered/allocated while consuming result input from backend).

regards,
Yeb Havinga

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