TRUNCATE TABLE feature was actually introduced in IDS starting with 10.00.xC4 version but with restrictions and one of the restrictions was it did not work on Enterprise Replication replicated tables. But starting with Cheetah release this will be supported even on the replicated tables. This feature introduces TRUNCATE TABLE as a supported operation on a replicated table while replication is active, which basically eliminates need for dropping and redefining the replicate and saves time for DBAs. This feature will support TRUNCATE TABLE on local table only, meaning ER will not propagate the TRUNCATE operation to other participants. The TRUNCATE command needs to be issued on each participant as needed. There are plans to implement the propagation of command in future along with other alter operations(ALTER, RENAME).

One of the key uses of TRUNCATE support which is in conjunction with cdr sync is, if there is a significant difference between the source and the target, the customer might elect to perform a truncate table followed by a cdr sync command. This would be faster than performing a cdr repair because the cdr repair must scan the data pages in primary key order while the sync does not. The cdr sync/repair features were introduced in 10.x which basically provided the ability to recognize the differences between tables, between multiple nodes within the replication domain, while ER running and take necessary action as instructed.

Vijay Lolabattu[Read More]

From IDS 10.0x onwards, Enterprise Replication (ER) supports alteroperations on a replicated table while replication is active however, RENAMEsupport was not one of them but that changes in Cheetah. IDS 11.x willstart supporting RENAME on ER columns, tables and databases. This featuresimplifies DBA tasks and increases data availability. Without this feature, theDBA would have to plan on a time in which ER could be removed from the objectso that the rename could be performed. This would require advanceplanning and scheduling during non-peek hoursfor performing the rename.

When a RENAME operation is performedaffected replicate definitions will be updated to reflect the impact of theRENAME and a control message will be sent to the other servers informing themof the rename. RENAME operation is allowed onlyon a mastered replicate. It does not propagate the RENAME command itself, there are plans to implement that too inthe future. The user simply will issue a rename DDL statement on each of theservers that are affected by RENAME. If therename is a column or a table, then the replicate will be cycled (cdr stop/start replicate) in much thesame way that occurs with a table ALTER. If a database rename occurs,however, ER will be cycled (cdr stop/start). This cycling will only occur if the renameaffects something on the local node. In all cases, the rename will causea control message to be sent to the other servers within the replication domainso that the syscdr database is correctlyupdated.

Vijay Lolabattu[Read More]