slapindex Required or Not

[ldap@mm.st]

I am in the process of rebuilding our ldap servers that are many years
old to run on RH5.   I basically took the existing slapd.conf file from
the old server and am using it on the new server (minor changes).   I
did a slapcat on the old server,  modified the schema a little and did a
slapadd on the new.  Systems seem to be able to authenticate against the
new test server and things seem to function corretly.  For now, the db
backend is  ldbm.  It has the following index statements:

index   objectClass,uid,uidNumber,gidNumber,memberUid   eq
index   cn,mail,surname,givenname                       eq,subinitial

I'm unclear of when and if it is required to run slapindex on the new
server.  Is this something that should be done after slapadd and should
it be done on a regular basis?  I assume you should stop slapd when this
is run.