Обсуждение: Re: [HACKERS] PL/Perl list value return causes segfault

On Fri, Jul 29, 2005 at 11:24:37PM -0400, Bruce Momjian wrote:
>
> Would someone who knows perl update plperl.sgml and send me a patch?
>
> Also, is this still true in 8.1:
>
>       In the current implementation, if you are fetching or returning
>       very large data sets, you should be aware that these will all go
>       into memory.

That's no longer true.  Please find enclosed a new patch :)

Cheers,
D
--
David Fetter david@fetter.org http://fetter.org/
phone: +1 510 893 6100   mobile: +1 415 235 3778

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David Fetter wrote:

>*** 716,724 ****
>
>      <listitem>
>       <para>
>!       In the current implementation, if you are fetching or returning
>!       very large data sets, you should be aware that these will all go
>!       into memory.
>       </para>
>      </listitem>
>     </itemizedlist>
>--- 766,776 ----
>
>      <listitem>
>       <para>
>!       If you are fetching or returning very large data sets using
>!       <literal>spi_exec_query</literal>, you should be aware that
>!       these will all go into memory.  You can avoid this by using
>!       <literal>spi_query</literal>/<literal>spi_fetchrow</literal> as
>!       illustrated earlier.
>       </para>
>      </listitem>
>     </itemizedlist>
>
>
>
>

You have rolled 2 problems into one - spi_query+spi_fetchrow does not
address the issue of returning large data sets.

Suggest instead:

<para>

       If you are fetching very large data sets using
       <literal>spi_exec_query</literal>, you should be aware that
       these will all go into memory.  You can avoid this by using
       <literal>spi_query</literal> and <literal>spi_fetchrow</literal>
    as illustrated earlier.
</para>
<para>
    A similar problem occurs if a set-returning function passes
    a large set of rows back to postgres via
    <literal>return</literal>. You can avoid this
    problem too by instead using <literal>return_next</literal> for
    each row returned, as shown previously.
</para>




cheers

andrew

On Sat, Jul 30, 2005 at 09:47:58AM -0400, Andrew Dunstan wrote:
>
>
> David Fetter wrote:
>
> You have rolled 2 problems into one - spi_query+spi_fetchrow does not
> address the issue of returning large data sets.
>
> Suggest instead:

[suggestion]

Revised patch attached.  Thanks for catching this :)

Cheers,
D
--
David Fetter david@fetter.org http://fetter.org/
phone: +1 510 893 6100   mobile: +1 415 235 3778

Remember to vote!

Patch applied.  Thanks.

---------------------------------------------------------------------------


David Fetter wrote:
> On Sat, Jul 30, 2005 at 09:47:58AM -0400, Andrew Dunstan wrote:
> >
> >
> > David Fetter wrote:
> >
> > You have rolled 2 problems into one - spi_query+spi_fetchrow does not
> > address the issue of returning large data sets.
> >
> > Suggest instead:
>
> [suggestion]
>
> Revised patch attached.  Thanks for catching this :)
>
> Cheers,
> D
> --
> David Fetter david@fetter.org http://fetter.org/
> phone: +1 510 893 6100   mobile: +1 415 235 3778
>
> Remember to vote!

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