On 28/01/15 06:29, Andrew Gierth wrote:
"Peter" == Peter Geoghegan <p...@heroku.com> writes:
Peter> What I find particularly interesting about this patch is that it
Peter> makes sorting numerics significantly faster than even sorting
Peter> float8 values,
Played some more with this. Testing on some different gcc versions
showed that the results were not consistent between versions; the latest
I tried (4.9) showed float8 as somewhat faster, while 4.7 showed float8
as slightly slower; the difference was all in the time of the float8
case, the time for numeric was virtually the same.
For one specific test query, taking the best time of multiple runs,
float8: gcc4.7 = 980ms, gcc4.9 = 833ms
numeric: gcc4.7 = 940ms, gcc4.9 = 920ms
(vs. 650ms for bigint on either version)
So honestly I think abbreviation for float8 is a complete red herring.
Also, I couldn't get any detectable benefit from inlining
DatumGetFloat8, though I may have to play more with that to be certain
(above tests did not have any float8-related modifications at all, just
the datum and numeric abbrevs patches).
Since gcc5.0 is due to be released in less than 3 months, it might be
worth testing with that.
Cheers,
Gavin
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