One of the nice new features in DAC 7.9 is the facility to assemble all the ETLs required to populate a fact using the Assemble button
In the Pre DAC 7.9 days, the process for building a star schema was as below
- Think up all the tasks required to populate a star schemas (Basically the Informatica workflows)
- Create the tasks and Identify Dependent and Depending on tables manually when creating a task.
- Construct a Table Group where one had to figure out all tables that belong to the star schema i.e. the fact and related dimensions
- And then at last build the Subject Area
- Run the subject area and then curse yourself for not remembering some tables.
- Start all over again.
- You don’t have to identify Dependent and Depending on tables. There is a sync feature which automatically identifies all the sources and targets which are affected/dependent on a task
- The concept of a Table Group is dead. You just have to name the fact to be populated and click on the Assemble button
- Click option: selected task only (unless you want to assemble for all subject areas delivered out of the box. Trust me : you don’t want to do this)
- The DAC assembles the selected subject area by determining what dimensions and other related tables are required, and what tasks are needed to load these tables.
- You will receive an informational message when the assemble process is comp
- Hey presto, the Subject Area is ready
But wait a minute,
- You still have to do some cleanup and remove unwanted tasks
- Click the Tasks tab to view which tasks the DAC has determined are required for this subject area
- Tasks that are automatically assigned to the subject area by the DAC are indicated with the Auto generated check mark.
- You can inactivate a task from participating in the subject area by selecting the Inactive check box.
- When the Inactive check box is selected, the task remains inactive even if you reassemble the subject area.
- You can also remove a task from the subject area using the Add/Remove command, but when you remove a task it is only removed from the subject area until you reassemble the subject area
- You still have to put in the implicit dependencies i.e. dependencies on tables that are not featured in the select statements or the workflow
- Upgrade does not work for custom workflows setup in DAC
There’s still more
- Unless you have a lot of time on your hands, don’t try clicking on the Assemble tab when DAC server has been up for some time
- Stop the server, restart the client and then click on Assemble
- It is much quicker. But don’t know why it works this way
So in conclusion Oracle DAC 7.9 is great and has some nice new features. But upgrading is going to be no fun. More on this later.
–Posted by Raghunatha Yadav/Sanjay Rao