On Tue, Sep 16, 2014 at 11:33 PM, Andrei Borzenkov <arvidjaar@gmail.com> wrote:
Regards,
Stefan
According to /usr/lib/rpm/rpmdb_stat -d /var/lib/rpm/Packages the hash has 19 buckets, and the database contains 3042 keys. Thus every bucket has 150 elements average. I doubt this hash has better access times than a BTree ...
The disk access pattern is horrible, see the attached graphic ...
This seems to confirm what you said above and that hash function seems to be good :) It looks like it cycles through hash buckets on linear scan.
Or it could be that it's scanning the hash index sequentially but accessing something else in tandem with a join, and that's random. -- To unsubscribe, e-mail: opensuse-factory+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-factory+owner@opensuse.org