Hi! I'm facing somewhat similar problems - I've stuffed about 10 thousand databases, most of them are pretty small and not very active, and some of the queries are extremely slow. I've tried different filesystems, and currently I'm using bleeding-edge reiser4 filesystem. It handles large directories very well, commands like `find /var/lib/mysql|wc -l` complete under a second, but when for example authenticated user does SHOW DATABASES query, it takes about 15 seconds to complete. I'm pretty sure it's not OS or filesystem issue, cause during this query mysqld process consumes all available CPU time in user-land (if it was FS or OS issue, it would use kernel CPU time). I've tried pretty much anything I can think of, but can't seem to solve the problem. Splitting the databases between several mysqld instances will help of course, but it will be pretty tough to administer. I'm going to complile mysqld from sources with profiling enabled, then gather profiling info, and submit it as a bug. Seems that's the only thing that may help.
On 4/1/06, Gary Huntress <[EMAIL PROTECTED]> wrote: > I have been offering free database hosting for over 4 years and I've > been doing it on a shoestring. My last MySQL server was a generic > 1GHz system with 256MB RAM running Redhat 9. The performance was > surprisingly good because the query loads were not typically high. One > persistent problem was the initial connection times. On that old > system if I had less than approx 10,000 separate databases then the > connection times were "fast", and on the order of 1 second or so. If I > had more than 10,000 databases this dramatically changed the connection > times to well over 15 seconds or more. > > I always attributed this connection lag to a problem with the filesystem > and the large number of directories. The old server had RH9 and ext3 > with no htree support which I was told could help with this problem. > > I recently bought a new 2.4 GHz system with 1GB of RAM and installed > Fedora 4 with ext3 and htree support. All new hardware, faster drives, > more RAM and updated software. I thought I was golden! Well, I have > 14,000 databases on this new system and it is as slow as the old 1GHz > system. > > The tuning articles I've read, and the sample my-*.cnf files that ship > with the tarball appear to apply to the more typical installation of a > single huge database rather than thousands of individual dbs. Can > anyone offer any suggestions? > > Thanks, > > Gary Huntress > > > -- > MySQL General Mailing List > For list archives: http://lists.mysql.com/mysql > To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED] > > -- Alexey Polyakov -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
