From: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> |
---|---|
To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | "Robert Haas" <robertmhaas(at)gmail(dot)com>, "Dimitri Fontaine" <dim(at)hi-media(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: *_collapse_limit, geqo_threshold |
Date: | 2009-07-10 17:59:48 |
Message-ID: | 4A573B4402000025000286A7@gw.wicourts.gov |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
>> treat parentheses around JOIN operations as optimizer hints.
>
> That's a *truly* horrid idea, as sometimes you need them simply to
> get the precedence correct.
You do, but it's been pretty rare in my experience, and we're
considering alternatives which give a lot less flexibility that this.
The *truly* awful thing about the SAP-DB implementation is that it
wasn't optional -- parentheses in this part of a query always limited
optimizer options; I sure wouldn't want to go there again. I thought
we were talking about options for what to do when an enable_* setting
was off for diagnostic purposes....
-Kevin
From | Date | Subject | |
---|---|---|---|
Next Message | Joshua Tolley | 2009-07-10 18:03:56 | git.postgresql.org vs. REL8_1_STABLE |
Previous Message | Tom Lane | 2009-07-10 17:52:20 | Re: *_collapse_limit, geqo_threshold |