If the nature of a replica database is such that the replicated data is used in a read-only manner or, more precisely, no replica changes are to be propagated to the master database, maintaining the history data can be avoided by using the following setting:

In that case, the following statement:

is not needed. If it has been already executed, the statement:

reverts the effect.

Note also that, in this case, ALTER TABLE ... SET HISTORY COLUMNS cannot be used.

By setting the SYS_SYNC_KEEPLOCALCHANGES parameter to YES, all the local changes and row inserts, if made, are kept despite the refresh or subscribe operations. This setting reduces processing load and storage requirements on the replica database. The use of this parameter should normally be limited to read-only replicas. However, in the cases where the replica database is a read-write database, and the application guarantees that all local replica writes are successfully propagated to the master database, this parameter can be set to YES as well.