Horton

Re: Retrieving query results

Igor Korot <ikorot01@gmail.com>

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From: Igor Korot <ikorot01@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Michael Paquier <michael.paquier@gmail.com>, pgsql-general <pgsql-general@postgresql.org>
Date: 2017-08-25T00:00:53Z
Lists: pgsql-general 
Hi,

On Thu, Aug 24, 2017 at 7:18 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Igor Korot <ikorot01@gmail.com> writes:
>> So there is no way to retrieve an arbitrary number of rows from the query?
>> That sucks...
>
> The restriction is on the number of rows in one PGresult, not the total
> size of the query result.  You could use single-row mode, or use a cursor
> and fetch some reasonable number of rows at a time.  If you try to inhale
> all of a many-gigarow result at once, you're going to have OOM problems
> anyway, even if you had the patience to wait for it.  So I don't think the
> existence of a limit is a problem.  Failure to check it *is* a problem,
> certainly.

Is there a sample of using single-row mode?
How to turn it on and turn it off?

Is there a cursor example with the Prepared Statements?
The one in the documentation doesn't use them - it uses PQexec().

Thank you.

>
>                         regards, tom lane

Commits

  1. Doc: document libpq's restriction to INT_MAX rows in a PGresult.

  2. Teach libpq to detect integer overflow in the row count of a PGresult.