From: [EMAIL PROTECTED]
Date: Sat, 13 Jan 2007 22:27:13 +0100
Hello,
the berkeley db is used for backend dbase for many ldap server.
I have read that the organization data in Berkely DB is made in btree,
hash recno ect. algorithms.
From source openldap I have view that the server open the berkely db
database using b-tree algorithm.
Yes.
This parameter has effect on the ldap server performances?
Certainly.
Is the b-tree order factor static?
I don't know what that is. What do you mean?
Is possible tuning this parameter?
If by "this parameter" you are referring to the choice of storage algorithm,
you can certainly modify the source code to try to use some other algorithm.
Our experience testing the hash algorithm showed that it offered worse
performance, so we've stuck with B-tree. Also the B-tree organization allows
us to iterate through a database in linear order, which is important for
enabling us to do Ordering indexing.
The recno format offers no advantages. The queue format can potentially
reduce locking contention, but only if all entries are of approximately equal
size and the size is known and configured in advance. Our experience with
actual deployments indicates that this constraint can't be met in the real
world. All in all, after all of the testing we've done (which has been
exhaustive and continues ongoing), the B-tree format is still the best so far.
There are of course other layouts with other advantages that we are also
investigating, but we won't be presenting that till further down the road.
(E.g., a monolithic BerkeleyDB B-tree is not a good data structure for use in
a cluster, if you want to be able to distribute LDAP operations across
multiple nodes in the cluster. With the popularity of blade computing, this
has become a more important consideration lately...)
--
-- Howard Chu
Chief Architect, Symas Corp. http://www.symas.com
Director, Highland Sun http://highlandsun.com/hyc
OpenLDAP Core Team http://www.openldap.org/project/
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