Hi John, we have recently done some tests with the Java bindings for Fastbit. The Java bindings seem to use the Fastbit C API internally.
When trying to get simple SELECTs to work with it, I didn't find a way to select using any aggregate functions. The select seems to run through well, and the C API has some functions to return the number of rows matched or the values for the result set of non-aggregate columns, however, I haven't found a way to access the results for any aggregate functions. Example: when selecting col1,COUNT(*) using the Java bindings or the C API, I can use getQualifiedLongs() or fastbit_get_qualified_longs() and friends to access the results. getQualifiedLongs() however needs a column name. Aggregate functions do not have a regular column name, and using an alias (e.g. "COUNT(*) AS n") does not help. I think the problem is that the C API called by the Java bindings will look for the column name in ibis::part which is the partition persistent on disk. The partition of course does not have any aggregate values, just the result set has them. However, using the API, there seems to be no access to the actual column names of the result set and so there is no way to retrieve any aggregate functions' values using the C API (and thus the Java bindings). Trying to access the result of an aggregate function will always fail in src/capi.cpp when calling ibis::part::getColumn(const char *att) in fastbit_get_qualified_*. My perception is that accessing aggregate functions' results using the Java bindings/C API is yet unimplemented. Or am I getting something wrong here? If not, are there any plans to support this in the future? Thank you for info on this and best regards Jan -- Jan Steemann Team Manager Development Panel | [email protected] Phone +49 2233 7933 752 | Fax +49 2233 7933 788 Globalpark AG | Kalscheurener Str. 19a | 50354 Huerth | Germany Vorstand/Chief Executive Officer (CEO) | Dr. Lorenz Graef Vorsitzender d. Aufsichtsrats/Chairperson of the Supervisory Board | Dr. Richard C. Geibel HRG Amtsgericht Koeln/Entered on Cologne Local Court Commercial Register | HRB 64032 GLOBALPARK - manage what matters | http://www.globalpark.de _______________________________________________ FastBit-users mailing list [email protected] https://hpcrdm.lbl.gov/cgi-bin/mailman/listinfo/fastbit-users
