From: Timothy H. Keitt <Timothy.Keitt@StonyBrook.Edu>
To: alexey@price.ru
Cc: pgsql-interfaces@postgresql.org
Subject: Re: Subject: unbuffered results from libpq?
Date: Mon, 21 May 2001 11:05:41 -0400
Message-ID: <3B092EC5.9060906@StonyBrook.Edu> (raw)
References: <01051819460400.12019@workshop.price.ru>
I realized after this post that one solution is to use a cursor. You
can then fetch in small chuncks and write to a local buffer. The
problem for a general interface applicaiton such as mine is nested
transactions --- cursors can only be used within transactions which will
fail if the the user has independently initiated a transaction (unless
this has been fixed).
Tim
Alexey Nalbat wrote:
> Hello.
>
> I have exactly the same question. Could anybody answer it?
>
> My impression is that it can't be maid. Even use of functions PQsetnonblocking,
> PQsendQuery, PQgetResult, PQconsumeInput,.. doesn't help. Is it so?
>
> Thanks.
>
>
>>My impression is that libpq buffers all results of a query. Is there a
>>way to get a "result stream" from the backend instead of having libpq
>>read everything into a local buffer first? Currently, my application,
>>after a query, simply copies the entire buffer from the libpq side into
>>storage on the application side. This seems expensive for large
>>queries. I'd rather read results directly into storage on the
>>application side, i.e., "while input get next value from backend". (I
>>know about libpqeasy, but this only iterates over the libpq buffer.)
>>
>
--
Timothy H. Keitt
Department of Ecology and Evolution
State University of New York at Stony Brook
Stony Brook, New York 11794 USA
Phone: 631-632-1101, FAX: 631-632-7626
http://life.bio.sunysb.edu/ee/keitt/
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To: pgsql-interfaces@postgresql.org
Cc: Timothy.Keitt@StonyBrook.Edu, alexey@price.ru
Subject: Re: Subject: unbuffered results from libpq?
In-Reply-To: <3B092EC5.9060906@StonyBrook.Edu>
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