alamb opened a new issue, #8518:
URL: https://github.com/apache/arrow-datafusion/issues/8518
### Describe the bug
When I call a function like `random()` twice I expect to get different
values, but I only get a single value
### To Reproduce
```sql
❯ select random() r1, random() r2;
+--------------------+--------------------+
| r1 | r2 |
+--------------------+--------------------+
| 0.5798857099939392 | 0.5798857099939392 |
+--------------------+--------------------+
1 row in set. Query took 0.002 seconds.
```
### Expected behavior
I expect the values from the two different calls to `random()` to be
different
### Additional context
The explain plan shows what is wrong:
```sql
❯ explain select random() r1, random() r2;
+---------------+--------------------------------------------------------------------+
| plan_type | plan
|
+---------------+--------------------------------------------------------------------+
| logical_plan | Projection: random() AS random() AS r1, random() AS
random() AS r2 |
| | Projection: random() AS random()
|
| | EmptyRelation
|
| physical_plan | ProjectionExec: expr=[random()@0 as r1, random()@0 as r2]
|
| | ProjectionExec: expr=[random()]
|
| | PlaceholderRowExec
|
| |
|
+---------------+--------------------------------------------------------------------+
```
And explain verbose shows the problem is introduced in logical_plan after
`common_sub_expression_eliminate`:
```sql
❯ explain verbose select random() r1, random() r2;
+------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------+
| plan_type | plan
|
+------------------------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------+
| initial_logical_plan | Projection:
random() AS r1, random() AS r2
|
| |
EmptyRelation
|
| logical_plan after inline_table_scan | SAME TEXT AS
ABOVE
|
....
|
| logical_plan after eliminate_cross_join | SAME TEXT AS
ABOVE
|
| logical_plan after common_sub_expression_eliminate | Projection:
random() AS random() AS r1, random() AS random() AS r2
|
| | Projection:
random() AS random()
|
| |
EmptyRelation
```
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