From: | Stephen Frost <sfrost(at)snowman(dot)net> |
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To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
Cc: | Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, PgHacker <pgsql-hackers(at)postgresql(dot)org>, Shigeru Hanada <shigeru(dot)hanada(at)gmail(dot)com>, Jim Mlodgenski <jimmy76(at)gmail(dot)com>, Peter Eisentraut <peter_e(at)gmx(dot)net>, Kohei KaiGai <kaigai(at)kaigai(dot)gr(dot)jp> |
Subject: | Re: [v9.5] Custom Plan API |
Date: | 2014-05-08 13:32:13 |
Message-ID: | 20140508133213.GP2556@tamriel.snowman.net |
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Lists: | pgsql-hackers |
* Simon Riggs (simon(at)2ndQuadrant(dot)com) wrote:
> On 8 May 2014 13:48, Stephen Frost <sfrost(at)snowman(dot)net> wrote:
> > I don't view on-GPU memory as being an alternate *permanent* data store.
>
> As I've said, others have expressed an interest in placing specific
> data on specific external resources that we would like to use to speed
> up queries. That might be termed a "cache" of various kinds or it
> might be simply be an allocation of that resource to a specific
> purpose.
I don't think some generalized structure that addresses the goals of
FDWs, CustomPaths, MatViews and query cacheing is going to be workable
and I'm definitely against having to specify at a per-relation level
when I want certain join types to be considered.
> > Perhaps that's the disconnect that we have here, as it was my
> > understanding that we're talking about using GPUs to make queries run
> > faster where the data comes from regular tables.
>
> I'm trying to consider a group of use cases, so we get a generic API
> that is useful to many people, not just to one use case. I had
> understood the argument to be there must be multiple potential users
> of an API before we allow it.
The API you've outlined requires users to specify on a per-relation
basis what join types are valid. As for if CustomPlans, there's
certainly potential for many use-cases there beyond just GPUs. What I'm
unsure about is if any others would actually need to be implemented
externally as the GPU-related work seems to need or if we would just
implement those other join types in core.
Thanks,
Stephen
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