Will you now? Databases of tens of terabytes are commonplace now in the relational world. Petabytes are the new frontier.
Now if you had said that there was a correlation between a particular data access pattern and the interest in a non-relational datastore you might be onto something, but size most definitly isn't it, and TPS isn't it either.
"Now if you had said that there was a correlation between a particular data access pattern and the interest in a non-relational datastore you might be onto something," - actually, that's what I was really getting at here with my comment that "They know what they are doing, and why they are doing it." These are not people who are puttering around with a few million rows and throwing up their hands in disgrace because they screwed up their keys. These are people who have tried everything to make RDBMS work, and RDBMS just couldn't do it. Repeatedly. (Seems like every major web site tells that story.)
RDBMS are awesome. They are not the absolute last word in data storage. (Heck, RDBMS as they stand today aren't even the last word in relational data storage.)
Now if you had said that there was a correlation between a particular data access pattern and the interest in a non-relational datastore you might be onto something, but size most definitly isn't it, and TPS isn't it either.