What's in a datatype then? A MySQL SMALLINT? A C int? An Oracle BLOB? One thing is for sure, they are not very well standardized, not even within the same environment, and much less so across them. And what does it means, really? When should I use a BLOB, when a BINARY VARCHAR and when to use a long long?

A datatype defines many attributes:

• What data I can store in it: Only numbers? Printable alaphanumeric characters? Unicode? Binary data? An object?
• What I can do with a value of that particular type and how does it behave? Can I concatenate two values? Add them (that is NOT the same as concatenate! The same operator (+) may be used, but it's not the same thing!)? Save it to a file?
• How is it stored and represented in technical terms. And this can be argued, a C int doesn't define how it is stored on disk, but a MySQL INT does! And a BLOB is a type that is largely there just because it …

I like the 5.4 developments, overall. It has useful stuff and is being developed and released a reasonable pace. Good progress. While perusing the MySQL 5.4.4 changelog, one particular change drew my attention, since it’s been (re)appearing since 2006. It’s the removal of the TYPE= keyword which was obsoleted since MySQL 4.1 in favour of the ENGINE= syntax in CREATE/ALTER TABLE.

While on the surface it may seem ok to remove the obsolete keyword, there are quite a few apps out there that use it, and that cannot be changed. So these will now be unable to use MySQL 5.4 or beyond. I filed this as a bug in 2006, MySQL bug#17501. If you’re interested in the “history of reappearance”, take a peek at the comments and their timeline. I just put in a new comment to note the 5.4.4 change. …