Re: improve transparency of bitmap-only heap scans

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, David Steele <david(at)pgmasters(dot)net>, James Coleman <jtc331(at)gmail(dot)com>, Alexey Bashtanov <bashtanov(at)imap(dot)cc>, Emre Hasegeli <emre(at)hasegeli(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: improve transparency of bitmap-only heap scans
Date: 2020-03-24 19:14:30
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

I took a quick look through this patch. While I see nothing to complain
about implementation-wise, I'm a bit befuddled as to why we need this
reporting when there is no comparable data provided for regular index-only
scans. Over there, you just get "Heap Fetches: n", and the existing
counts for bitmap scans seem to cover the same territory.

I agree with the original comment that it's pretty strange that
EXPLAIN doesn't identify an index-only BMS at all; but fixing that
is a different patch.

regards, tom lane

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Andres Freund 2020-03-24 19:16:51 Re: Fastpath while arranging the changes in LSN order in logical decoding
Previous Message Andres Freund 2020-03-24 19:13:46 Re: Adding a test for speculative insert abort case