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Re: commit: ldap/servers/slapd config.c proto-slap.h schema_init.c slap.h

Hallvard B Furuseth wrote:

Kurt D. Zeilenga wrote:

It might be worthwhile to use present indices where
no keys substrings keys are found. Could also use
it narrow ordering to just those entries where the
attribute is present.

Such a change might have messed up things for us, if we needed presence indices.

We will be using sizelimit size.unchecked to make too general queries
fail at once:
- partly so users won't have to sit wait for a while and then just get
 timelimitExceeded anyway,
- partly for privacy protection,
- partly for the sake of server speed.

We have found that we'll need to set the unchecked limit uncomfortably
high for the sake of substring searches, but at least it does still cut
off a lot of such searches.  Possibly we'll add a bunch of invisible
dummy entries to make it fail more reliably, or something.  Anyway, that
high limit means that with the above change, a lot more queries will
pass the unchecked test only to fail the filter.

Your concern makes no sense. You've taken measures to compensate for a particular type of search being too expensive in server time, and now that the possibility exists to make those searches more efficient you perceive this as a problem? You already said that your unchecked limit is uncomfortably high; using this proposed fallback would allow you to set a much lower unchecked limit. It seems to me that the proposed behavior is a win on all counts.

Howard Chu writes:

Of course, in practice, I never use presence indices. I wonder how many people do.

Probably quite a lot, since I think some OpenLDAP documentation says or said that if one has an equality index (I think), one might just as well add a presence index, since that takes very little extra space. I believe that's why we had presence indices.

Well, if there is any documentation that says this, it is wrong. The presence and equality indices are about equal in size.

 -- Howard Chu
 Chief Architect, Symas Corp.       Director, Highland Sun
 http://www.symas.com               http://highlandsun.com/hyc
 Symas: Premier OpenSource Development and Support