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Re: back-mdb status

Howard Chu wrote:
The write rate is pretty slow, as we already knew. I frankly don't see it
improving very much, given the single-writer nature of MDB.

I guess "slow" is relative. My previous modrate tests didn't touch any indices. I've added entryCSN,entryUUID eq indexing to the config (since that's common for a syncrepl environment) and gotten much different results.

Basically for back-hdb there's a continuous stream of deadlocks from updating the entryCSN index. This pushes the maximum mod rate down to only 3400/sec. With this configuration back-mdb was actually faster, at 3800/sec.

With accesslog thrown into the mix, back-mdb drops to 2500/sec while back-hdb drops to 1700/sec. So for any realistic scenario, back-mdb beats back-hdb all around.

  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/