Chad Callihan occasionally inserts something:
Have you ever maxed out the SQL Server table column limit yet still needed more columns? Hopefully not considering SQL Server has a max limit of 1024 columns per table. But as I found out, it’s possible for someone to reach out and ask for even more. Sparse columns are an option to consider when you can’t get enough. Let’s take a look at what sparse columns are and how they can be used.
Sparse columns have very little utility, except in the most “I don’t think you’re doing it right” scenarios. Still, if you happen to end up in that scenario, there is a way out, though I’d really want to understand the nature of the data in that problem and, knowing just the amount of detail in the scenario that I do, would lean toward storing the data either in an unpivoted fashion (one row per entity * attribute in an EAV-style “‘additional attributes” table) or as a JSON string and let the client sort it out.