I felt like writing a lot about the great potential fit between MySQL and Solid over the weekend, but Solid didn’t want me to do so. Now, however, I’m not in the mood, so I’ll just say that in OLTP, Solid’s technology is strong where MySQL’s is weak, and vice-versa. E.g., Solid is so proud of its zero-administration capabilities that, without MySQL, it doesn’t have much in the way of admin tools at all. Conversely, I think that many of those websites that crash all the time with MySQL errors would crash less with the Solid engine underneath. (Solid happens to be proud of its BLOB-handling capability, efficiency-wise.)
Neither outfit is good in data warehousing, or in text search, image search, etc. (Solid slings big files around, but it doesn’t peer closely inside them). But for OLTP of tabular or dumb media data, this looks like a great fit.
Whether anybody will care, however, is a different matter.
Lisa Vaas of eWeek offers a survey of the many MySQL engine options.
EDIT: Another Lisa Vaas article makes it clear that MySQL is planning to compete in data warehousing/OLAP as well.