[trurl]

It seems misleading to call this "Datalog". The GitHub repo even says "among database theoreticians Datalog and SQL are known to be equivalent", which is absolutely wrong without qualification. Some flavors of SQL will have recursive extensions so that they could be considered equivalent, but that is not true in general.

I can't find any mention of recursion on the original blog post or the GitHub page. Without recursion it isn't Datalog.

[zoshi]

A major difference between Datalog and SQL is that Datalog uses set semantics, whereas SQL uses bag semantics. For those not aware, that means facts in datalog are unique. SQL’s equivalent to facts (records) are not unique, and relations can contain duplicates.

[layer8]

SQL 99 has recursion via recursive CTEs, so the claim is probably valid.

[trurl]

Fair enough, but to a database theoretician SQL means "non-recursive conjunctive queries". And I skimmed the tutorial and there is not a single example of using Logica to compute something recursively. Transitive closure is the canonical example for showing off Datalog.

[molham]

SQL 99 only requires support for linear recursion, i.e. "each FROM has at most one reference to a recursively-defined relation". Datalog doesn't have such a restriction