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Re: Index for objectclass does not work...
2011/1/6 Howard Chu <hyc@symas.com>:
> Steeg Carson wrote:
>>
>> 2011/1/4 Quanah Gibson-Mount<quanah@zimbra.com>:
>>>
>>> --On Tuesday, January 04, 2011 1:43 AM +0100 Steeg Carson
>>> <steeg.carson@googlemail.com> wrote:
>>>
>>>> I simulate this on my database just right now:
>>>
>>> I suggest you read:
>>>
>>> <http://www.openldap.org/lists/openldap-technical/201011/msg00146.html>
>>>
>>> to understand how indices and their slots work.
>>>
>>
>> As I now understand, the entire index for one attribute (e.g.
>> objectClass) is "split" in several indexes. They holds for each
>> path/node (resp. DN, but not leaf) an separate index for this
>> attribute with all "hits" for his subtree (and for onelevel too).
>
> No. Only the dn2id table maintains any notion of nodes and subtrees. All
> indices are global to the database and have no notion of scope.
But what does mean (from
http://www.openldap.org/lists/openldap-technical/201011/msg00146.html):
"Ordinarily at each level of the tree we keep an index tallying all of
the children beneath that point. In back-bdb this index is used for
subtree searches and for onelevel searches."
So if I do a search, I'll get every time ALL results (ID's) from the
index for the searched value. If my search uses additionally a
searchbase the slapd takes all ID's and lookup in id2entry.bdb to get
the DN for the ID and compare?
>
>> If I do an ldapsearch with -b "cn=ownPath,ou=root" the slapd takes the
>> index which is bound on this node/DN?
>>
>> In my DIT are 470812 entires.
>>
>> The objectClass=subEngine exists 104384 times in the entire directory
>> (ou=root).
>> The objectClass=subEngine exists only 1 time under "cn=ownPath,ou=root",
>
> By default an index slot can only maintain 65535 records before it overflows
> and loses precision. Once it loses precision, you tend to get results like
> this. If you need to accomodate larger indices you can tweak a constant in
> back-bdb/back-bdb.h and recompile. You'll probably also need to increase
> LDAP_PVT_THREAD_STACK_SIZE.
>
> Another workaround, without recompiling, would be to sort your entries such
> that all of the entries of the subEngine class are loaded in contiguous
> order.
>
Can you recommend a good book, where I can read all such things and
understand, how openldap really works? This are all very important
things for design and operation.
Thanks for helping
Steeg