One of the most complex issues in Data Warehousing is how to detect changes on your source system. Most data warehouses do a complete dump and load of all the data during the nightly load. With Dbvisit Replicate and the new Audit functionality, only data that has been changed can be loaded real time into the Data Warehouse. This allows for reduced processing and real time updates of the Data Warehouse.
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Audit will only work for individual tables that are replicated. It is not supported if a whole schema is replicated. |
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LONG datatypes should be excluded from tables included in Audit replication as Oracle only permit one LONG datatype per table. Attempts to create, or have Dbvisit Replicate, create an Audit functionality enabled table on the target will throw a "ORA-01754: a table may contain only one column of type LONG" error. These columns can be excluded as per the following instructions. |
How does Audit work
Dbvisit Replicate creates a copy of the source table as a staging table in the target database and inserts a record into this staging table every time there is a change in the source table (for Update, Delete, Insert). This means that even with an updated or delete in the source system, a new record is created in the target (or staging) table. The staging table holds a new record for every change in the source system.
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If a column name is already of maximum length ( 30 characters) then Dbvisit Replicate implicitly renames such long column names on target, with old_ and new_ prefix, to keep the length of target column name 30 characters. |
Dbvisit Replicate Audit - loading of real-time data warehouses
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