SQL alone is just a query language. the MySQL design docs Snowden shared were primitive installations that did not meet the claimed capability of their surveillance system.
Also, Snowden didn't build the query system, he just used it. He built a document gathering system, which I described in my other response. These are different services.
The amount of compute and indexing needed was extraordinary, and the evidence presented didn’t meet that bar.
Yes I believe that the NSA, in theory, had the budget to complete this task, and to a lesser degree, the competence. . But I only believe claims with complete evidence.
Google had already demonstrated such a system by the late 90s, using off the shelf technology.