If the nature of the 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, maintaining of the history data may be avoided by setting:
set sync parameter SYS_SYNC_KEEPLOCALCHANGES ’Yes’;
In that case, the statement:
ALTER TABLE ... SET SYNCHISTORY
is not needed. If it has been already executed, the statement:
ALTER TABLE ... SET NOSYNCHISTORY
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 at the Replica. The use of this parameter should normally be limited to read-only replicas. However, in the cases where the Replica is a read-write database, and the application guarantees that all local replica writes are successfully propagated to the Master, this parameter can be set to "Yes" as well.