Greg Stark writes:
On Tue, Apr 17, 2012 at 5:38 PM, Tom Lane wrote:
This has been discussed before, but it always seemed that the
cost-benefit ratio was exceedingly questionable.  You don't get any
savings whatsoever unless you reduce the size of the null bitmap across
a MAXALIGN boundary, which more and more often is 64 bits, so that the
frequency with which the optimization wins anything doesn't look likely
to be that high.
There is the usage pattern where (brace yourself) people have
thousands of columns in which they have all but a handful be null.
They might be pretty happy about this.
Oh, I don't doubt that there are *some* use cases for this. I'm just
dubious about how much we'd be slowing things down for everybody else.
As I said, what I'd like to see are some benchmarks, and not just
benchmarks that are tuned to match the sort of case where this wins.

regards, tom lane

Search Discussions

Discussion Posts

Previous

Follow ups

Related Discussions

Discussion Navigation
viewthread | post
posts ‹ prev | 4 of 28 | next ›
Discussion Overview
grouppgsql-hackers @
categoriespostgresql
postedApr 17, '12 at 4:23p
activeAug 10, '12 at 12:06a
posts28
users8
websitepostgresql.org...
irc#postgresql

People

Translate

site design / logo © 2021 Grokbase