On 9/14/2013 12:44 PM, Howard Chu wrote:
Ah totally forgot about that, it's been a couple years since I looked inside that code. LMDB updates record counts on every write op so returning the count is zero-cost. (Ironically we don't use this fact to optimize filter evaluation order in OpenLDAP. Probably should...) Also due to the fact that writing a leaf page requires every page up to the root to be updated (copy-on-write design), updating the counts also comes "for free" since the root page had to be updated anyway. (Or put another way, LMDB writes are already slow by design; updating the counters doesn't make them any slower.)
BDB has a similar feature. We're just having a little trouble finding it ;) -- 389-devel mailing list 389-devel@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/389-devel
