Horton

Re: Early WIP/PoC for inlining CTEs

David Fetter <david@fetter.org>

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From: David Fetter <david@fetter.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andreas Karlsson <andreas@proxel.se>, Thomas Munro <thomas.munro@enterprisedb.com>, Andrew Gierth <andrew@tao11.riddles.org.uk>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-11-16T22:41:07Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Prevent inlining of multiply-referenced CTEs with outer recursive refs.

  2. Allow user control of CTE materialization, and change the default behavior.

  3. Split QTW_EXAMINE_RTES flag into QTW_EXAMINE_RTES_BEFORE/_AFTER.

  4. document when PREPARE uses generic plans

On Fri, Nov 16, 2018 at 04:15:10PM -0500, Tom Lane wrote:
> Andreas Karlsson <andreas@proxel.se> writes:
> >  [ inlining-ctes-v5.patch ]
> 
> I took a little bit of a look through this.  Some thoughts:
> 
> * I think it'd be a good idea if we made OFFSET/LIMIT in a CTE be an
> alternate way of keeping it from being inlined.  As the patch stands,
> if that's the behavior you want, you have no way to express it in
> a query that will also work in older servers.  (I will manfully
> resist suggesting that then we don't need the nonstandard syntax
> at all ... oops, too late.)

If we're on board with exposing pilot error, we could decide not to
implement the nonstandard WITH syntax. One type of pilot error this
would expose is a situation where:

- A UDF has side effects, but is declared IMMUTABLE
- A WITH clause calls it in order to get those side effects on the
  entire result set

Best,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778

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