Replication of large objects from blobspaces or sbspaces

Enterprise Replication retrieves the large object data directly from the blobspace or sbspace and then sends the data to the target database server.

It is possible that a transaction subsequent to the transaction that is being replicated can modify or delete a simple or smart large object that Enterprise Replication is trying to retrieve. If Enterprise Replication encounters a row whose large object (simple or smart) was modified or deleted by a subsequent transaction, Enterprise Replication does not send the data in the large object. In most cases, the subsequent transaction that modified or deleted the large object is also replicated, so the data again becomes consistent when that transaction is replicated. The data in the large object is inconsistent for only a short time.

The following conditions apply to replicating large objects that are stored in blobspaces or sbspaces:
  • Enterprise Replication does not support replication of large object updates performed outside of a row update.
  • After you update a large object that is referenced explicitly in the table schema, you must update the referencing row before Enterprise Replication can replicate the updated smart large object. For example:
    UPDATE table_name SET large_object_column = x
  • Enterprise Replication replicates updates to in-place smart large objects by sending a new copy of the entire smart large object. Enterprise Replication does not send only the logged changes to update smart large objects.
  • Enterprise Replication does not support sharing out-of-row data (multiple references to a large object) during replication. If you try to replicate multiple references to the same large object on the source database server, Enterprise Replication does not re-create those references on the target database server. Instead, Enterprise Replication creates multiple large objects on the target database server.

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