Re: Optimize PL/Perl function argument passing [PATCH]

On Mon, Jan 31, 2011 at 02:22:37PM -0500, Andrew Dunstan wrote:
> 
> 
> On 01/15/2011 12:31 AM, Alex Hunsaker wrote:
> >On Tue, Dec 7, 2010 at 07:24, Tim Bunce<Tim.Bunce@pobox.com>  wrote:
> >>Changes:
> >>
> >>    Sets the local $_TD via C instead of passing an extra argument.
> >>    So functions no longer start with "our $_TD; local $_TD = shift;"
> >>
> >>    Pre-extend stack for trigger arguments for slight performance gain.
> >>
> >>Passes installcheck.
>
> >Cool, surprisingly in the non trigger case I saw up to an 18% speedup.

That's great.

> >The trigger case remained about the same, I suppose im I/O bound.
> >
> >Find attached a v2 with some minor fixes, If it looks good to you Ill
> >mark this as "Ready for Commit".
> >
> >Changes:
> >- move up a declaration to make it c90 safe
> >- avoid using tg_trigger before it was initialized
> >- only extend the stack to the size we need (there was + 1 which
> >unless I am missing something was needed because we used to push $_TD
> >on the stack, but we dont any more)
> 
> This looks pretty good. But why are we bothering to keep $prolog at
> all any more, if all we're going to pass it is &PL_sv_no all the
> time? Maybe we'll have a use for it in the future, but right now we
> don't appear to unless I'm missing something.

PostgreSQL::PLPerl::NYTProf would break if it was removed, so I'd rather
it wasn't.

I could work around that if there's an easy way for perl code to tell
what version of PostgreSQL. If there isn't I think it would be worth
adding.

Tim.