Re: Early WIP/PoC for inlining CTEs

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Andreas Karlsson <andreas(at)proxel(dot)se>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, David Fetter <david(at)fetter(dot)org>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Early WIP/PoC for inlining CTEs
Date: 2019-01-18 20:44:46
Message-ID: CA+Tgmoa1q0_UPSpjSAscXE5=YsoXOgFnzHhceciKTyt35s7Ekg@mail.gmail.com
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On Fri, Jan 18, 2019 at 3:42 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2019-01-18 15:34:46 -0500, Robert Haas wrote:
> > On Thu, Jan 17, 2019 at 10:48 AM Andreas Karlsson <andreas(at)proxel(dot)se> wrote:
> > > On 1/11/19 8:10 PM, Robert Haas wrote:
> > > > WITH cte_name [[NOT] MATERIALIZED] AS (query) main_query...
> > >
> > > Hm, when would one want "NOT MATERIALIZED"? I am not sure I see the
> > > usefulness of forcing inlining other than if we by default do not inline
> > > when a CTE is referenced multiple times.
> >
> > When the planner materializes it, but the performance of the resulting
> > plan therefore sucks, I suppose.
> >
> > I don't feel super-strongly about this, and Tom is right that there
> > may be cases where materialization is just not practical due to
> > implementation restrictions.
>
> *not* materializing I assume?

Right, sorry.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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