Here's one: https://arxiv.org/pdf/1208.0084v1.pdf https://arxiv.org/pdf/1208.0084v1.pdf (Note the involvement of IBM. Dunno whether this has made it into DB2,

Here's one: https://arxiv.org/pdf/1208.0084v1.pdf https://arxiv.org/pdf/1208.0084v1.pdf (Note the involvement of IBM. Dunno whether this has made it into DB2, but a lot of really interesting research has; also keep in mind that whatever IBM wants to put in DB2 has a high probability of making it into the SQL standard).