A good article, Amit - thanks.

I'd like to add another reason to use the smallest appropriate datatype - and that's the way SQL Server stores data.

Yes, disk drives are getting cheaper by the minute, but a page of data in SQL Server is still fixed at 8K.

For Index leaf pages, the smaller the datatype, the more index keys can fit on an 8K page and, all things being equal, the less logical reads required for an index seek.

For tables with a clustered index, it's even more important, as the index leaf pages contain the actual rows of data. The smaller the data rows, the more rows on an 8K page, the faster the access.

Best regards,

SteveR