One of the more common requests I hear from my clients is that they’d like to be able to compare year-to-year membership data (e.g., current number of members vs. same time last year or same time three years ago).

What they often find, however, is that pulling historical data from their primary transactional database can be problematic. Data in transactional databases can change over time, which can affect historical queries and reports.

The best way to address this issue is to take regular snapshots of key data or reports. For example, many of my clients run a monthly report of members (including total count, count by category and company/names). These reports are then saved in a shared or network drive so that they can be accessed by anyone on staff. This way, when the association wants to compare today’s member counts to some time in the past, a query is run for the current counts and then compared to any of the snapshots that have been saved over time.

Transactional databases are good for transactions. They’re not as good at keeping historical data (the older the data the less accurate it will be). This is where snapshots can be a lifesaver.