(ITS#8220) refint performance issue

[hyc@openldap.org]

Full_Name: Howard Chu
Version: 2.4
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (78.155.231.135)
Submitted by: hyc


The fix for ITS#5097 changed refint to support subtree renames. Unfortunately
this required using dnSubtreeMatch extended search filters, which are not
indexable, so every refint invocation invokes a search that scans the entire
DB.

This behavior isn't necessary; such an extensive search is only needed if we
know that the entry being modified actually has children. If we know that the
entry has no children, we can use the original code which used an equality
match, which *is* indexable, and save significant overhead.

Patch coming shortly.