On 5/2/17 4:44 PM, Andrew Dunstan wrote:



On 05/02/2017 10:13 AM, Merlin Moncure wrote:
On Sun, Apr 30, 2017 at 6:21 PM, Andres Freund <and...@anarazel.de> wrote:
On 2017-04-30 07:19:21 +0200, Pavel Stehule wrote:
why we cannot to introduce GUC option - enable_cteoptfence ?
Doesn't really solve the issue, and we've generally shied away from GUCs
that influence behaviour after a few bad experiences.  What if you want
one CTE inlined, but another one not?
Yeah.  Are we absolutely opposed to SQL syntax against WITH that
allows or disallows fencing?   for example,

WITH [MATERIALIZED]

Pushing people to OFFSET 0 is a giant step backwards IMO, and as in
implementation detail is also subject to change.



Agreed, it's an ugly as sin and completely non-obvious hack.


Isn't OFFSET 0 an implementation detail anyway? Who says the planner couldn't get smarter in the future, realize OFFSET 0 is no-op?

In that case replacing CTE optimization fence with "OFFSET 0" would be akin to painting yourself into a corner, waiting for the pain to dry, walking over to another corner and painting yourself into that one.

cheers

--
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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