Presto: Count distinct on multiple columns

[tesseract2048]

Hi there,

In our system, queries like:
SELECT COUNT(DISTINCT _col0, _col1, _col2) .....
are commonly used.

Surely we can rewrite these to CONCAT etc., before submitting to presto.
Is there any plan to support these kind of queries, or any other suggestions?
Thanks.

[electrum]

The next version (0.148) will have this using the row constructor:

SELECT count(DISTINCT row(col1, col2, col3)) FROM ...

[electrum]

This is currently in the master branch. You can try it out now:

presto> select count(distinct orderstatus || ',' || clerk) from tpch.tiny.orders;
 _col0 
-------
  2310 
(1 row)

presto> select count(distinct row(orderstatus, clerk)) from tpch.tiny.orders;
 _col0 
-------
  2310 
(1 row)

[yew1eb]

@electrum
this can't work, when col1 / col2 / col3s value contains Null.

SELECT count(DISTINCT row(col1, col2, col3)) FROM ...