Re: FILTER for aggregates [was Re: Department of Redundancy Department: makeNode(FuncCall) division]

On 21 June 2013 05:01, David Fetter <david(at)fetter(dot)org> wrote:
> What tests do you think should be there that aren't?
>

I think I expected to see more tests related to some of the specific
code changes, such as

CREATE TABLE t AS SELECT * FROM generate_series(1,10) t(x);

-- Should fail (filter can't be used for non-aggregates)
SELECT abs(x) FILTER (WHERE x > 5) FROM t;

-- Should fail (filter clause can't contain aggregates)
SELECT array_agg(x) FILTER (WHERE x > AVG(x)) t;

-- OK (aggregate in filter sub-query)
SELECT array_agg(x) FILTER (WHERE x > (SELECT AVG(x) FROM t)) FROM t;

-- OK (trivial sub-query)
SELECT array_agg(x) FILTER (WHERE (SELECT x > 5)) FROM t;

-- OK
SELECT array_agg(x) FILTER (WHERE (SELECT x > (SELECT AVG(x) FROM t))) FROM t;

-- OK
SELECT array_agg(x) FILTER (WHERE (SELECT (SELECT t.x > AVG(t2.x) FROM
t as t2))) FROM t;

-- Should fail
SELECT array_agg(x) FILTER (WHERE (SELECT (SELECT 5 > AVG(t.x) FROM t
as t2))) FROM t;

-- OK (filtered aggregate in window context)
SELECT x, AVG(x) OVER(ORDER BY x), AVG(x) FILTER (WHERE x > 5)
OVER(ORDER BY x) FROM t;

-- Should fail (non-aggregate window function with filter)
SELECT x, rank() OVER(ORDER BY x), rank() FILTER (WHERE x > 5)
OVER(ORDER BY x) FROM t;

-- View definition test
CREATE VIEW v AS SELECT array_agg(x) FILTER (WHERE (SELECT (SELECT t.x
> AVG(t2.x) FROM t as t2))) FROM t;
\d+ v

etc...

You could probably dream up better examples --- I just felt that the
current tests don't give much coverage of the code changes.

Regards,
Dean