| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| 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 20:42:38 |
| Message-ID: | 20190118204238.zb6vogaeqkzduapu@alap3.anarazel.de |
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| Lists: | pgsql-hackers |
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?
Greetings,
Andres Freund
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