| From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
|---|---|
| To: | Nico Williams <nico(at)cryptonector(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Mapping MERGE onto CTEs (Re: MERGE SQL Statement for PG11) |
| Date: | 2017-11-01 17:14:03 |
| Message-ID: | 20171101171403.mhl5z3uxfi6xa76t@alvherre.pgsql |
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| Lists: | pgsql-hackers |
Nico Williams wrote:
> As an aside, I'd like to be able to control which CTEs are view-like and
> which are table-like. In SQLite3, for example, they are all view-like,
> and the optimizer will act accordingly, whereas in PG they are all
> table-like, and thus optimizer barriers.
There was a short and easy to grasp (OK, maybe not) discussion on the
topic of CTEs acting differently. I think the consensus is that for
CTEs that are read-only and do not use functions that aren't immutable,
they may be considered for inlining.
https://www.postgresql.org/message-id/5351711493487900@web53g.yandex.ru
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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