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Re: Retrieve all the returned rows in one call

From: Sean Davis <sdavis2(at)mail(dot)nih(dot)gov>
To: pgsql-interfaces(at)postgresql(dot)org
Cc: "Andreas Gidlund" <vaxis(at)hotmail(dot)com>
Subject: Re: Retrieve all the returned rows in one call
Date: 2006-10-09 15:30:06
Message-ID: 200610091130.06335.sdavis2@mail.nih.gov (view raw or flat)
Thread:
Lists: pgsql-interfaces
On Monday 09 October 2006 10:58, Andreas Gidlund wrote:
> I am right now using the libpq interface and struggling with efficiently
> retrieve the result from a query.
>
> Let's say I run a select statement with some where clauses and then
> retrieve the result into a PGresult. I want to know if there is an
> efficient way to retrieve all the rows at once? I am going to return a
> char*** from my function, i.e. a two-dimensional array of char pointers.
> I have seen the COPY sql command, but up to v8.1 i cannot use a select
> statement with it, the only way to customize COPY is to choose which
> columns to return, but still, the only option is to return the whole table.
> Furthermore, when using PQgetCopyData I get the whole row at once, but I
> still have to loop through all rows.
> I have also seen in the PGresult structure that it has a member called
> tuples, which is a two-dimensional array of the structure PGresAttValue.
> This is a way to recieve all the data at once, but it is in a format which
> is specific for PostgreSQL and I am developing a database interface
> including other databases two, so I want to use a general structure
> returned from the function, i.e. a char***. This means that I would have to
> loop through the tuples array to convert into the char array structure, and
> hence lose the whole meaning with recieving all the rows at once.
>
> So my question is if it is possible in any way to retrieve the result in
> the form of char***?

I think the answer is no.  

Sean

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