Re: ToDo: fast update of arrays with fixed length fields for PL/pgSQL

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Andres Freund <andres(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: ToDo: fast update of arrays with fixed length fields for PL/pgSQL
Date: 2013-10-03 07:23:48
Message-ID: CAFj8pRDxCGTZbFJ4CM2v+PS4OTy9Co9d2prwW407kYU9KdLbUQ@mail.gmail.com
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2013/10/3 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>

> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
> > If you can do a update of some array in plpgsql now, then you have to
> work
> > with local copy only. It is a necessary precondition, and I am think it
> is
> > valid.
>
> If the proposal only relates to assignments to elements of plpgsql local
> variables, it's probably safe, but it's also probably not of much value.
> plpgsql has enough overhead that I'm doubting you'd get much real-world
> speedup. I'm also not very excited about putting even more low-level
> knowledge about array representation into plpgsql.
>

I looked to code, and I am thinking so this can be done inside array
related routines. We just have to signalize request for inplace update (if
we have a local copy).

I have not idea, how significant speedup can be (if any), but current
behave is not friendly (and for multidimensional arrays there are no
workaround), so it is interesting way - and long time I though about some
similar optimization.

Regards

Pavel

>
> regards, tom lane
>

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