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From Lars Francke <lars.fran...@gmail.com>
Subject Returning multiple values from an UDF
Date Thu, 13 Jan 2011 18:10:51 GMT
Hello,

I'm looking for help with UDFs.

I need a UDF to do something like this:
SELECT parseCoordinates(latitude, longitude) AS lat, lng FROM foo;

But I'm not sure how. I've implemented a UDF using GenericUDF
returning a struct with two fields and that works as in me getting
back a struct (e.g. "{"latitude":2.0,"longitude":10.0}") but that's
still one field and I don't know how to split that back in two
columns. I could obviously store that in an intermediate table but
that seems like a hassle and I'd like to avoid it.

Any ideas how to do this properly?

I've tried things like:
SELECT parseCoordinates(latitude, longitude) AS lat, lng FROM foo;
SELECT parseCoordinates(latitude, longitude) AS (lat, lng) FROM foo;
SELECT parseCoordinates(latitude, longitude) AS bar, bar.latitude AS
lat, bar.longitude AS lng FROM foo;

etc. but I always get an error: FAILED: Error in semantic analysis: AS
clause has an invalid number of aliases

Thanks a lot.

Cheers,
Lars

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