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Re: [PATCH 2/5] Make relpathbackend return a statically result instead of palloc()'ing it

From: Andres Freund <andres(at)2ndquadrant(dot)com>
To: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: [PATCH 2/5] Make relpathbackend return a statically result instead of palloc()'ing it
Date: 2013-01-08 21:00:10
Message-ID: 20130108210010.GD10185@awork2.anarazel.de (view raw or flat)
Thread:
Lists: pgsql-hackers
On 2013-01-08 22:47:43 +0200, Heikki Linnakangas wrote:
> On 08.01.2013 22:39, Andres Freund wrote:
> >On 2013-01-08 15:27:23 -0500, Tom Lane wrote:
> >>Andres Freund<andres(at)2ndquadrant(dot)com>  writes:
> >>>Uhm, we don't have&  need palloc support and I don't think
> >>>relpathbackend() is a good justification for adding it.
> >>
> >>I've said from the very beginning of this effort that it would be
> >>impossible to share any meaningful amount of code between frontend and
> >>backend environments without adding some sort of emulation of
> >>palloc/pfree/elog.  I think this patch is just making the code uglier
> >>and more fragile to put off the inevitable, and that we'd be better
> >>served to bite the bullet and do that.
> >
> >If you think relpathbackend() alone warrants that, yes, I can provide a
> >wrapper. Everything else is imo already handled in a sensible and not
> >really ugly manner? Imo its not worth the effort *for this alone*.
> >
> >I already had some elog(), ereport(), whatever emulation but Heikki
> >preferred not to have it, so its removed by now.
> >
> >To what extent do you want palloc et al. emulation? Provide actual pools
> >or just make redirect to malloc and provide the required symbols (at the
> >very least CurrentMemoryContext)?
> 
> Note that the xlogreader facility doesn't need any more emulation. I'm quite
> satisfied with that part of the patch now. However, the rmgr desc routines
> do, and I'm not very happy with those. Not sure what to do about it. As you
> said, we could add enough infrastructure to make them compile in frontend
> context, or we could try to make them rely less on backend functions.

Which emulation needs are you missing in the desc routines besides
relpathbackend() and timestamptz_to_str()? pfree() is "just" needed
because its used to free the result of relpathbackend(). No own pallocs,
no ereport ...

Greetings,

Andres Freund

-- 
 Andres Freund	                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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Next:From: Heikki LinnakangasDate: 2013-01-08 21:02:15
Subject: Re: [PATCH 2/5] Make relpathbackend return a statically result instead of palloc()'ing it
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Subject: Re: PATCH: optimized DROP of multiple tables within a transaction

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