Modification conflict scenarios

Modification conflicts resolve automatically and no manual action is required. The LDAPModify operation allows the following modification types:

Add of one or more values
Delete of one or more values or the entire attribute
Replacement of all values

Replication does not currently support the increment LDAP modification type.

The following illustration presents a modification conflict scenario.

Processing steps

LDAP client A sends a modify request to directory server A.
LDAP client B sends a conflicting modify request to directory server B.
Directory server A applies the modification.
Directory server B applies the modification.
The LDAP clients receive successful responses.
Replication propagates the updates.
Conflict resolution on directory server A updates the entry to reflect the value on directory server B.

Conflict resolution on directory server B ignores the update received from directory server A.

The following table shows the result of a modification conflict depending on the type of updates that occur. For all of the operations in the table, assume the following:

LDAP Modify 1 was applied at PingDirectory server 1.
LDAP Modify 2 was applied at PingDirectory server 2.
LDAP Modify 1 occurred shortly before LDAP Modify 2, so that PingDirectory server 2 received LDAP Modify 1 after LDAP Modify 2 was applied.

Modification Conflict Scenarios
Modify 1	Modify 2	Result of Conflict Resolution at PingDirectory server 2 When Modify 1 is received
`Add` of a single-value attribute	`Add` of the same attribute with a different value	Incoming `Modify` is ignored.
`Delete` of a single-valued attribute	Replacement of the value of the same attribute	Incoming `Delete` is ignored.
Replacement of a single-valued attribute	`Delete` of the same attribute	Incoming Replacement is ignored.
`Delete` some values from a multi-valued attribute	`Delete` some values from a multi-valued attribute	Incoming `Delete` is ignored.
`Delete` a multi-valued attribute	`Delete` of the same multi-valued attribute	Incoming `Delete` is ignored.
`Delete` a multi-valued attribute	`Add` the same multi-valued attribute	Incoming `Delete` is ignored.
`Delete` value X from a multi-valued attribute	`Delete` value X from the same multi-valued attribute	Incoming `Delete` is ignored.
`Delete` value X from a multi-valued attribute	`Add` value Y to the same multi-valued attribute	`Delete` of value X is applied.
`Delete` value X from a multi-valued attribute	`Delete` value Y from the same multi-valued attribute	`Delete` of value X is applied.
`Delete` value X from a multi-valued attribute	Replace all values of the same multi-valued attribute	Incoming `Delete` is ignored.
`Add` of values X and Y to a multi-valued attribute	`Delete` value X from the same multi-valued attribute	Only value Y is added.
`Delete` value X from a multi-valued attribute	`Add` of values X and Y to the same multi-valued attribute	Incoming `Delete` is ignored.

PingDirectory

Modification conflict scenarios