Re: docs update for count(*) and index-only scans

From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Josh Kupershmidt <schmiddy(at)gmail(dot)com>, pgsql-docs <pgsql-docs(at)postgresql(dot)org>
Subject: Re: docs update for count(*) and index-only scans
Date: 2011-11-04 21:30:54
Message-ID: CAOR=d=364hfCt9XjXYVKXig-++M=hBRPd9u4k=TnBhioKW-8xA@mail.gmail.com
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On Fri, Nov 4, 2011 at 2:10 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Tue, Nov 1, 2011 at 8:07 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> It's the "lobotomized engines" that are the problem, IMO --- people
>> coming from databases like mysql tend to think count(*) just means
>> reading a table size counter that the engine has anyway.
>
> This is probably a much less common misconception than formerly, due
> to the rise of InnoDB and the falling-out-of-favor experienced by
> MyISAM.

True. For instance the Drizzle project simply yanked myisam as an
engine out of mysql for their fork, and made innodb the standard
default table handler.

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