Hi, This is probably an abuse of the Clojure forum, but it is a bit Clojure-related and strikes me as the sort of thing that a bright, eclectic bunch of Clojure users might know about. (Plus I'm not really a software person, so I need all the help I can get.)
I am looking at the possibility of finding/building a declarative data aggregation language operating on a small relational representation. Each query identifies a set of rows satisfying some relational predicate and calculates some aggregate function of a set of values (e.g. min, max, sum). There might be ~20 input tables of up to ~1k rows. The data is immutable - it gets loaded and never changed. The results of the queries get loaded as new rows in other tables and are eventually used as input to other computations. There might be ~1k queries. There is no requirement for transaction management or any inherent concurrency (there is only one consumer of the results). There is no requirement for persistent storage - the aggregation is the only thing of interest. I would like the query language to map as directly as possible to the task (SQL is powerful enough, but can get very contorted and opaque for some of the queries). There is considerable scope for optimisation of the calculations over the total set of queries as partial results are common across many of the queries. I would like to be able to do this in Clojure (which I have not yet used), partly for some very practical reasons to do with Java interop and partly because Clojure looks very cool. * Is there any existing Clojure functionality which looks like a good fit to this problem? I have looked at Clojure-Datalog. It looks like a pretty good fit except that it lacks the aggregation operators. Apart from that the deductive power is probably greater than I need (although that doesn't necessarily cost me anything). I know that there are other (non- Clojure) Datalog implementations that have been extended with aggregation operators (e.g. DLV http://www.mat.unical.it/dlv-complex/dlv-complex). Tutorial D (what SQL should have been http://en.wikipedia.org/wiki/D_%28data_language_specification%29#Tutorial_D) might be a good fit, although once again, there is probably a lot of conceptual and implementation baggage (e.g. Rel http://dbappbuilder.sourceforge.net/Rel.php) that I don't need. * Is there a Clojure implementation of something like Tutorial D? If there is no implementation of anything that meets my requirements then I would be willing to look at the possibility of creating a Domain Specific language. However, I am wary of launching straight into that because of the probability that anything I dreamed up would be an ad hoc kludge rather than a semantically complete and consistent language. Optimised execution would be a whole other can of worms. * Does anyone know of any DSLs/formalisms for declaratively specifying relational data aggregations? Thanks Ross -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
