Re: [HACKERS] PQdeleteTuple function in libpq

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Andrew Chernow <ac(at)esilo(dot)com>
Cc: Pavel Golub <pavel(at)gf(dot)microolap(dot)com>, Pavel Golub <pavel(at)microolap(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, pgsql-interfaces <pgsql-interfaces(at)postgresql(dot)org>
Subject: Re: [HACKERS] PQdeleteTuple function in libpq
Date: 2011-06-02 15:02:08
Message-ID: 1307026778-sup-415@alvh.no-ip.org
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Excerpts from Andrew Chernow's message of jue jun 02 10:12:40 -0400 2011:

> > Andrew, why we have PQmakeEmptyPGresult, PQcopyResult,
> > PQsetResultAttrs, PQsetvalue and PQresultAlloc in this case? Of course
> > there's no big deal with their absence but let's be consistent.
>
> I'm not entirely sure what you are trying to do, but can't you use
> PQmakeEmptyPGresult, PQsetResultAttrs and PQsetvalue to construct a
> result that excludes the tuples you don't want followed by a
> PQclear(initial_result)?

Seems pretty wasteful if you want to delete a single tuple from a large
result. I think if you desired to compact the result to free some
memory after deleting a large fraction of the tuples in the result it
could be useful to do that, otherwise just live with the unused holes in
the storage area as suggested by Pavel.

--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

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