Re: explain analyze rows=%.0f

Tom Lane <tgl@sss.pgh.pa.us>

From: Tom Lane <tgl@sss.pgh.pa.us>
To: Joshua Tolley <eggyknap@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Euler Taveira de Oliveira <euler@timbira.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2009-05-29T17:30:36Z
Lists: pgsql-hackers
Joshua Tolley <eggyknap@gmail.com> writes:
> On Thu, May 28, 2009 at 11:12:42PM -0400, Robert Haas wrote:
>> On Thu, May 28, 2009 at 11:00 PM, Euler Taveira de Oliveira
>>> Don't you think is too strange having, for example, 6.67 rows?
>> 
>> No stranger than having it say 7 when it's really not.  Actually mine
>> mostly come out 1 when the real value is somewhere between 0.5 and
>> 1.49.  :-(

> +1. It would help users realize more quickly that some of the values in the
> EXPLAIN output are, for instance, *average* number of rows *per iteration* of a
> nested loop, say, rather than total rows found in all loops.

I think it would only be sensible to show fractional digits if nloops is
greater than 1.  Otherwise the value must in fact be an integer, and
you're just going to confuse people more by suggesting that it might not
be.

			regards, tom lane

Commits

  1. EXPLAIN: Always use two fractional digits for row counts.

  2. Adjust EXPLAIN test case to filter out "Actual Rows" values.

  3. Allow EXPLAIN to indicate fractional rows.

  4. Fix pgbench performance issue induced by commit af35fe501.