[pacman-dev] tardb - Was: pacman cold caches performance, too much stat()ing

Allan McRae allan at archlinux.org
Sat Dec 12 19:44:22 EST 2009

Dan McGee wrote:
> I think most of this thread is the wrong approach to the problem.
> Rather than try to meld the DB to fit pacman, we should just swap out
> DBs so it doesn't have these bad worst-case conditions.
> $ du -sh --apparent-size local/ sync/*
> 15M	local/
> 8.4M	sync/community
> 31K	sync/community-testing
> 812K	sync/core
> 11M	sync/extra
> 302K	sync/testing
> With those numbers in mind, we're talking about ~30 to ~35 MB of raw
> text data here. That is not a lot of data; most hard drives have at
> least ~30 MB/sec performance so this whole mess could be read in under
> a second if it was stored in a single file. So that would be one way
> of thinking about the issue differently.

Has anyone looked at the idea of using a single tarball for each db 
recently?  From memory, most of the issues of treating the reading from 
archives in a style like a file stream had been solved when looking at 
changelogs.  Having said that, I have not looked at that code since it 
was implemented...


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