Por que o slapd diz “bdb_equality_candidates: (objectClass) não indexado” quando os índices realmente existem?

Question

Eu tenho o slapd 2.4.31-1+nmu2ubuntu8.3 instalado no Ubuntu 14.04 e rodando como master para uma sincronização secundária. Ele funciona bem para todas as coisas LDAP, mas eu noto esses erros em /var/log/debug de vez em quando:

May 19 09:19:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (uid) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (objectClass) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (objectClass) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (uid) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (objectClass) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (objectClass) not indexed
May 19 09:20:01 ldap1 slapd[9507]: <= bdb_equality_candidates: (uid) not indexed

Esses índices já existem (criados através do link )? Eu posso vê-los quando eu corro slapcat -n 0 . Preciso criá-los para mestre e escravo? (as entradas olcDatabase={2} e /var/lib/ldap/accesslog parecem indicar que elas existem apenas para a configuração do escravo)

dn: olcDatabase={1}hdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcHdbConfig
olcDatabase: {1}hdb
olcDbDirectory: /var/lib/ldap
...
olcDbIndex: entryCSN eq
olcDbIndex: entryUUID eq
...
dn: olcDatabase={2}hdb,cn=config
objectClass: olcDatabaseConfig
objectClass: olcHdbConfig
olcDatabase: {2}hdb
olcDbDirectory: /var/lib/ldap/accesslog
olcSuffix: cn=accesslog
olcRootDN: cn=admin,dc=xxxxxx,dc=xxxxx,dc=xxx
olcDbIndex: default eq
olcDbIndex: entryCSN,objectClass,reqEnd,reqResult,reqStart
olcDbIndex: entryUUID eq
olcDbIndex: memberUid eq
olcDbIndex: uniqueMember eq
olcDbIndex: cn pres,sub,eq
olcDbIndex: sn pres,sub,eq
olcDbIndex: uid pres,sub,eq
olcDbIndex: displayName pres,sub,eq
olcDbIndex: default sub
olcDbIndex: uidNumber eq
olcDbIndex: gidNumber eq
olcDbIndex: mail,givenName eq,subinitial
olcDbIndex: dc eq
structuralObjectClass: olcHdbConfig