Hackers, We have a strong need to make a variant to the crosstab interface so that data that is pivoted one way would be sent through a crosstab like function so that it would be pivoted another way. For example, if you had
row 0: a1, a2, a3, k1, c1, c2, ... row 1: a1, a2, a3, k2, c1, c2, ... row 2: a1, a2, a3, k3, c1, c2, ... ... where 'a' columns are uninteresting attribute columns, 'k' is the dimension we want to pivot on, and c1->cN would be stacked vertically, so that we'd end up with, row 0: a1, a2, a3, c1, k1, k2, ... row 1: a1, a2, a3, c2, k1, k2, ... row 2: a1, a2, a3, c3, k1, k2, ... There are various SQL level approaches to this but they tend to be imperformant with large datasets so that I think a crosstab-like C implementation ought to be able to do better (or at least I hope so) since you have to cross product rows and columns in such a way that you can get a clean join. Cribbing from tablefunc.c I don't think this is a terrible challenge to do in hash table style. Questions on the table: *) Has anyone done anything like this or know of any current implementations? *) Would there be any interest in expanding tablefunc along these lines? thanks in advance, merlin
