fix: nested window function

[chenkovsky]

Which issue does this PR close?

• Closes Planning error for compound expressions involving window functions #14910

Rationale for this change

current implementation doesn't support nested window function in projection.

What changes are included in this PR?

use expr visitor to find nested window function.

Are these changes tested?

unit test

Are there any user-facing changes?

No

[chenkovsky]

sqllogictest complains stackoverflow. because I added a recursive visitor. but if I add stacksize, it works. so I think it's not real stackoverflow. Let me check how to refine it.

[chenkovsky]

@alamb I think I have to add a BFS visitor in sqlparse crate, how do you feel about it?

[alamb]

@alamb I think I have to add a BFS visitor in sqlparse crate, how do you feel about it?

i think that would mean it will take at least another month to fix this issue - as we would need a new sql parser release and then integrate that into DataFusion

If you can find another way that would likely be faster to get in

[chenkovsky]

@alamb I think I have to add a BFS visitor in sqlparse crate, how do you feel about it?

i think that would mean it will take at least another month to fix this issue - as we would need a new sql parser release and then integrate that into DataFusion

If you can find another way that would likely be faster to get in

I increased stack size in test

[chenkovsky]

i'm working on rewriting visit logic. but I found this pr apache/datafusion-sqlparser-rs#1522 . does it mean that this pr doesn't take effect on the test 🤔

[chenkovsky]

by the way, If I change tokio to single thread, there's also no stack overflow.

[chenkovsky]

@alamb could you please review it agian. I have found the solution that doesn't need to touch stack size.

[alamb]

I think we should at least have a .slt test that shows this query running and producing the same result as postgres, perhaps with a smaller number of series:

postgres=# SELECT
  t1.v1,
  SUM(t1.v1) OVER w
FROM
  generate_series(1, 5) AS t1(v1)
WINDOW
  w AS (ORDER BY t1.v1 ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW);
 v1 | sum
----+-----
  1 |   1
  2 |   3
  3 |   6
  4 |  10
  5 |  15
(5 rows)

[alamb]

I am sorry @chenkovsky and @2010YOUY01

I don't know what

SELECT
  t1.v1,
  SUM(t1.v1) OVER w + 1
FROM
  generate_series(1, 10) AS t1(v1)
WINDOW
  w AS (ORDER BY t1.v1);

Is supposed to be computing (what does adding one to a window definition like w +1 represent?)

[2010YOUY01]

DuckDB interprets it as (SUM(t1.v1) OVER w) + 1, and ... OVER (w + 1) is not valid

D SELECT
    t1.v1,
    SUM(t1.v1) OVER (w + 1)
  FROM
    generate_series(1, 10) AS t1(v1)
  WINDOW
    w AS (ORDER BY t1.v1);
Parser Error: syntax error at or near "+"
LINE 3:   SUM(t1.v1) OVER (w + 1)