While going over this patch I noticed this commit in HyperLogLog's
upstream:
https://github.com/hideo55/cpp-HyperLogLog/commit/b8cb5e7b856928af15e9535b4b1650f493ba453f
In the first hunk which is what we care about, the author is doing
bit-or of both hash values instead of taking the max value, which is
what we were doing.
Our transcript seems to predate that bugfix commit, so I assume we need
to apply this to our copy too. Sadly, Hideaki-san commit message isn't
very descriptive.
I don't really know how HyperLogLog works, so maybe we can't or
shouldn't apply the patch because of how the hash stuff is used.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
