Documentation

One of the problems we have is documentation and how to keep it up-to-date. We tend to deliver a new batch of reports as part of a CR (Change Request) then make changes as part of BAU (Business as usual) unless its a particularly complex or time consuming change. The problem is often BAU changes happen rapidly often within a short time frame and time isn’t always allocated to updating documentation.

Over time a small, simple change and evolve into a major change and the documentation can significantly drift out-of-sync. Documentation is an important part of the communication between developer, analysis and the end-user, without it misunderstanding and confusing can occur and errors and mistakes happen.

Whilst investigating how other are documentation work I rediscovered the much unloved extended property MS_Description. As you might have guess, using the description field to enter, yes, you guessed it, a description of the tables, views, stored procedure and other SQL objects. Speaking of naming – it’s also important to name things correctly. A table named dbo.Table1 helps no-one. I tend to name any temporary tables MS_TMP – this then quickly identities me as the owner and the fact it can most likely be destroyed. Any dimensions are prefix with Dim and facts are, yes, you’ve guessed it again – Fact.

I have a TSQL script that pulls this data into a table on the staging database as part of a SSIS package, this is configured a SQL Job, however it is only execute post-deployment – we use TeamCity to build the project and then OctopusDeploy for deploying to the various environments.

As we move towards using Analysis Services, I needed a way to document the cubes, luckily Alex Whittles from Purple Frog has already come up with a solution using the Dynamic Management Views (DMVs) and blogged about it – http://www.purplefrogsystems.com/blog/2010/09/olap-cube-documentation-in-ssrs-part-1/.

I have however modified it, I’ve followed the standard ETL process, so I’ve extracted the data from the DMVs into a staging data, like SQL objects, this is only executed post-deployment by a SQL job that is executed by OctopusDeploy task. I didn’t like the idea of dynamically querying the data every time and as we use continue integration\deployment I don’t need to worry about the data being out of data.

All I have left to really look at is documenting SSIS. Speaking of SSIS, I found Jamie Thomson post on naming conventions very useful.

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