On 5/25/16 7:46 AM, Kouhei Kaigai wrote:
My only concern is that domain type is not allowed to define type cast. If we could add type cast on domain, we can define type transformation from other array type to matrix.
I've actually wished for that in the past, as well as casting to compound types. Having those would make it easier to mock up a real data type for experimentation.
I strongly encourage you to talk to the MADlib community about first-class matrix support. They currently emulate matrices via arrays. I don't know offhand if they support NULLs in their regular matrices. They also support a sparsematrix "type" that is actually implemented as a table that contains coordinates and a value for each value in the matrix. Having that as a type might also be interesting (if you're sparse enough, that will be cheaper than the current NULL bitmap implementation).
Related to this, Tom has mentioned in the past that perhaps we should support abstract use of the [] construct. Currently point finds a way to make use of [], but I think that's actually coded into the grammar.
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