The revisions process described inRevisions Process discusses how revisions specs are structured and how specs are processed by the deployment utility. However, the question remains as to how to organize the revisions within the specs. Revisions that come with product updates handle that for the out-of-the-box BBDW database. With database extensions, you can ensure repeatability and ease of upgrade through thoughtful arrangement of revisions.
Some revisions actions, such as those to create tables, only need to be added to the set of revisions files once. A table stays in a database until deleted. For new deployments, the full set of revisions is processed for the first time. So, if a revision that adds a table is somewhere in the set of revisions files, the deployment utility adds the table. If the deployment utility is run subsequently as a redeployment, the table is already there.
Other revisions actions, such as those that update stored procedures, may need to appear repeatedly. For example, a stored procedure called RESETETL_EXT truncates tables and drops indexes. This action is necessary for all tables in the warehouse. When you add a new table, RESETETL_EXT requires an update to truncate the new table and drop its indexes. So, a revision that updates RESETETL_EXT should occur whenever there is a revision to create a table.
New sets of revisions should: