alamb opened a new issue, #6758:
URL: https://github.com/apache/arrow-datafusion/issues/6758
### Is your feature request related to a problem or challenge?
The way that DataFusion names the output columns can be quite messy. For
example, the query below produces a column named `"FIRST_VALUE(foo.free)
PARTITION BY [foo.host] ORDER BY [foo.time DESC NULLS FIRST] RANGE BETWEEN
UNBOUNDED PRECEDING AND CURRENT ROW + Int64(5) / Int64(12)"` (yes that whole
thing)
Arrow requires column names to be distinct strings and DataFusion creates
the name based on the content of the expression.
Here is the entire query
```sql
❯ create table foo(host varchar, free int, time int) as values ('a', 1, 2),
('a', 3, 4);
0 rows in set. Query took 0.003 seconds.
❯ select first_value(free) over (partition by host order by time desc) + 5 /
12 from foo limit 10;
+-------------------------------------------------------------------------------------------------------------------------------------------------------------+
| FIRST_VALUE(foo.free) PARTITION BY [foo.host] ORDER BY [foo.time DESC
NULLS FIRST] RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW + Int64(5) /
Int64(12) |
+-------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 3
|
| 3
|
+-------------------------------------------------------------------------------------------------------------------------------------------------------------+
2 rows in set. Query took 0.003 seconds.
```
It also means you can't select the same expression without an alias, which
while annoying is likely not a critical usecase
```sql
❯ select free / 1, free / 1 from foo;
Error during planning: Projections require unique expression names but the
expression "foo.free / Int64(1)" at position 0 and "foo.free / Int64(1)" at
position 1 have the same name. Consider aliasing ("AS") one of them.
❯ select free / 1, free / 1 as col2 from foo;
+---------------------+------+
| foo.free / Int64(1) | col2 |
+---------------------+------+
| 1 | 1 |
| 3 | 3 |
+---------------------+------+
```
### Describe the solution you'd like
While the output column names can be controlled via adding an explicit
alias, I think it would be good to have a more concise way of naming the
default outputs, especially for window functions
Perhaps something like not adding the `OVER` clause's contents so
`FIRST_VALUE(foo.free)` in the above example.
If we do this we need to be careful to allow multiple calls to `FIRST_VALUE`
with different `OVER` clauses in the same query
### Describe alternatives you've considered
_No response_
### Additional context
If we make the names more concise, we will probably need a solution like
https://github.com/apache/arrow-datafusion/issues/6543 to ensure they remain
unique
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