Re: WIP Patch: Precalculate stable functions, infrastructure v1

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Marina Polyakova <polyakova(dot)marina69(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Arthur Zakirov <a(dot)zakirov(at)postgrespro(dot)ru>, Aleksander Alekseev <a(dot)alekseev(at)postgrespro(dot)ru>
Subject: Re: WIP Patch: Precalculate stable functions, infrastructure v1
Date: 2018-01-24 20:10:56
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2018-01-16 17:05:01 -0500, Tom Lane wrote:
>> I'm curious to know whether Andres has some other ideas, or whether he
>> feels this is all a big wart on the compiled-expression concept.

> I don't have too many "artistic" concerns from the compiled expression
> POV. The biggest issue I see is that it'll make it a bit harder to
> separate out the expression compilation phase from the expression
> instantiation phase - something I think we definitely want.

Hmm, there's no such distinction now, so could you explain what you
have in mind there?

>> I don't think there are any existing cases where we keep any
>> meaningful state across executions of a compiled-expression data
>> structure; maybe that's a bad idea in itself.

> Storing all cached values in an EState or ExprContext (the
> latter referring to the former) somewhat alike the values for Param's
> sounds a lot more reasonable to me.
> ...
> This all reminds me a lot of the infrastructure for Params...

Yeah, one thing I was thinking about in connection with this is the
stuff associated with propagating changes in outer-reference Params
(the extParam/allParam/chgParam mess). I wonder if we could find
a way to unify that with this feature.

Keeping the stored value of a CachedExpr in a Param slot is an
interesting idea indeed.

regards, tom lane

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Thomas Munro 2018-01-24 20:13:10 Re: [HACKERS] Parallel tuplesort (for parallel B-Tree index creation)
Previous Message Andres Freund 2018-01-24 20:08:09 Re: pgsql: Add parallel-aware hash joins.