Horton

Re: Early WIP/PoC for inlining CTEs

Andreas Karlsson <andreas@proxel.se>

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From: Andreas Karlsson <andreas@proxel.se>
To: Tom Lane <tgl@sss.pgh.pa.us>, Andrew Gierth <andrew@tao11.riddles.org.uk>
Cc: David Fetter <david@fetter.org>, Thomas Munro <thomas.munro@enterprisedb.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2019-01-27T17:24:21Z
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 1/27/19 4:21 PM, Tom Lane wrote:
> Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
>> I'm not sure we should nail down the rule that the absence of NOT
>> MATERIALIZED will mean a multiply-referenced CTE is evaluated once. One
>> would hope that in the future the planner might be taught to inline or
>> not in that case depending on cost. I think it makes more sense to say
>> that we never inline if MATERIALIZED is specified, that we always inline
>> if NOT MATERIALIZED is specified, and that if neither is specified the
>> planner will choose (but perhaps note that currently it always chooses
>> only based on refcount).
> 
> I have no objection to documenting it like that; I just don't want us
> to go off into the weeds trying to actually implement something smarter
> for v12.

+1

Andreas