Re: BRIN cost estimate

From: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: David Rowley <david(dot)rowley(at)2ndquadrant(dot)com>, Emre Hasegeli <emre(at)hasegeli(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: BRIN cost estimate
Date: 2017-04-06 21:47:48
Message-ID: 20170406214748.3jhqwipgkbmj5pl4@alvherre.pgsql
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

Tom Lane wrote:

> TBH, I think that code is in the noise. It doesn't involve any disk
> access, or catalog access, or user-defined function calls. I wouldn't
> bother trying to account for it.

I removed it in the pushed version.

> What you should be accounting for is the ensuing heap page accesses,
> but I assume that's done somewhere else.

It's supposed to be accounted for, yeah.

One thing we do not account for is the number of extra heap accesses we
do for unsummarized ranges (mostly, heap has grown but the index doesn't
cover the new pages yet).

Álvaro Herrera
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Andres Freund 2017-04-06 21:50:35 Re: tuplesort_gettuple_common() and *should_free argument
Previous Message David Steele 2017-04-06 21:45:39 Re: increasing the default WAL segment size