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Re: Progress on fast path sorting, btree index creation time

Alvaro Herrera <alvherre@commandprompt.com>

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From: Alvaro Herrera <alvherre@commandprompt.com>
To: Jim Nasby <jim@nasby.net>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Geoghegan <peter@2ndquadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2012-02-02T01:30:18Z
Lists: pgsql-hackers

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  1. During btree index build, sort equal-keyed tuples according to their

Excerpts from Jim Nasby's message of mié feb 01 19:12:58 -0300 2012:
> On Jan 26, 2012, at 9:32 PM, Robert Haas wrote:
> > But if we want to put it on a diet, the first thing I'd probably be
> > inclined to lose is the float4 specialization.  Some members of the
> > audience will recall that I take dim view of floating point arithmetic
> > generally, but I'll concede that there are valid reasons for using
> > float8.  I have a harder time coming up with a good reason to use
> > float4 - ever, for anything you care about.  So I would be inclined to
> > think that if we want to trim this back a bit, maybe that's the one to
> > let go.  If we want to be even more aggressive, the next thing I'd
> > probably lose is the optimization of multiple sortkey cases, on the
> > theory that single sort keys are probably by far the most common
> > practical case.
> 
> I do find float4 to be useful, though it's possible that my understanding is flawed…
> 
> We end up using float to represent ratios in our database; things that really, honest to God do NOT need to be exact.

But then, do you sort using those ratios?

-- 
Álvaro Herrera <alvherre@commandprompt.com>
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