Re: Re: patch: fix performance problems with repated decomprimation of varlena values in plpgsql

On Wed, Jan 19, 2011 at 12:10 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Tue, Jan 18, 2011 at 5:22 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>>> opinion isn't strong in this topic. One or twenty useless detoasting
>>> isn't really significant in almost use cases (problem is thousands
>>> detoasting).
>
>> Yeah.  Many-times-repeated detoasting is really bad, and this is not
>> the only place in the backend where we have this problem.  :-(
>
> Yeah, there's been some discussion of a more general solution, and I
> think I even had a trial patch at one point (which turned out not to
> work terribly well, but maybe somebody will have a better idea someday).

I'm pretty doubtful that there's going to be a general solution to
this problem - I think it's going to require gradual refactoring of
problem spots.

> In the meantime, the proposal at hand seems like a bit of a stop-gap,
> which is why I'd prefer to see something with a very minimal code
> footprint.  Detoast at assignment would likely need only a few lines
> of code added in a single place.

OK.

--
Robert Haas
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