Database Development Life Cycle (DDLC)

The Gator dropped by today and suggested I have a little discuss on the Database Development Life Cycle. “Don’t you mean the Software Development Life Cycle?” Nope… databases are a lot different than software, although software does run and interact with the database. The database is a living, breathing thing that must be fed and nurtured to get the best performance out of it and the software that uses it. An executable or web service can be rebuilt from scratch every time, but once a database is being used in a production capacity you are left with modification in situ.

At Humana, I describe the Database Development Lifecycle thus:

  • Data Refresh
    • Metadata Exchange
    • Security Sync
  • Code Sync
    • Verification
  • Code Turn
    • Verification
  • Database Use
    • QA – UAT
    • Test – System/Integration Testing
    • Dev – Development

As I breakdown these items please keep in mind that not all elements are going to exist in every database environment.

Database Refresh – Data in lower environments (not production) grows stale over time. This stagnation allows the data, though use and testing, to get further from the real world of production. To combat this data stagnation the lower environments should occasionally be refreshed from the production source. More than likely a straight data replacement will not work: in most modern systems a certain amount of environmentally sensitive data exists and must be retained in the target database. To dig deeper into managing metadata, read about SQLDataCompare. Additionally, you will probably need to correct/sync security so that the target database has the correct security on it for the environment you are refreshing rather than the environment that the data came from (production).

Code Sync – When you refresh the data in the target environment, more than likely you will copy over the existing database, and then start modifying it to get it where it is supposed to be. Modern DBMS’s usually have a mix of data and code objects intermixed in the same storage system (It is possible to create boundaries between the two, but it is way beyond this conversation). So once you’ve done the ‘restore’ of production data on the target database, the code objects will need to be “sync’d” so that you can get the target environment back to where it was before the data refresh.

Example: Production is on release 11/08.12, QA is on 11.09.12, and Test/Dev is on 11.10. So if you refresh Test, its code base would be that of production, or 11.08, but it was on 11.10 so QA would need to be resync the database code (e.g., rerun the turn scripts for 11.09 and 11.10).

Once you think you’re sync’d then you need to perform verification to ensure that you know where your starting point is.

Code Promotion– Refreshes are usually at the start a development cycle, which means that you will probably run (test, prove, etc.) the next releases code base (scripts). If you are dealing with QA, the Turn Center will actually do the turn via a TCW. Code turns should ALWAYS be verified, regardless of who does them.

Database Use – This is why the database exists… utilization by an end-use process. QA and Test have the same end-use processes; just the audience is different. In Dev, the end-use process is the actual development and database script creation.

That is it in a nut shell. So….What do you consider the DDLC?

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