Modify performance improvement for back-ldbm and back-bdb (ITS#1526)

[gwingerde@home.nl]

Full_Name: Gertjan van Wingerde
Version: devel-snapshot & 2.0.19
OS: Linux/Solaris/True64
URL: ftp://ftp.openldap.org/incoming/Gertjan_van_Wingerde_openldap-snapshot-12012002-1.diff
Submission from: (NULL) (212.120.112.51)


I have improved the modify performance of OpenLDAP by only reindexing
attributes
that are actually changed in the modify operation instead of all the attributes
of
an entry. This change improves the performance of a modify operation on a
non-indexed
attribute from about 4 modifications per second to about 38 modifications per
second.
If an indexed attribute is being modified, the results are a bit less dramatic,
but
still an improvement of about 200% is observed then.
Note: The changes are only applicable to the LDBM backend and the BDB backend.
As far
as I can see no other backends can use this optimisation.

Patches for both the latest CVS snapshot as for the 2.0.19 release have been
uploaded
to ftp.openldap.org under the following names:
Gertjan_van_Wingerde-openldap-snapshot-12012002-1.diff     - Diffs for CVS
snapshot.
Gertjan_van_Wingerde-openldap-2.0.19-12012002-1.diff       - Diffs for 2.0.19
release.