Count(*) does not aggregate rows

[Hunterlige]

Checks

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars as pl

df = pl.DataFrame(
    {
        "id": ["1", "2", "3"],
        "bar": [6.0, 7.0, 8.0],
    }
)
print(df.sql("SELECT COUNT(*) FROM self"))

Log output

polars==1.21

| len |
|-----|
| 3   |
| 3   |
| 3   |

Log output

Issue description

From polars 1.18 version Count(*) returns too many rows and does not aggregate all the rows selected.

Expected behavior

polars==1.17

| len |
|-----|
| 3   |

Installed versions

--------Version info---------
Polars:              1.21.0
Index type:          UInt32
Platform:            Linux-6.1.85+-x86_64-with-glibc2.35
Python:              3.11.11 (main, Dec  4 2024, 08:55:07) [GCC 11.4.0]
LTS CPU:             False

----Optional dependencies----
Azure CLI            <not installed>
adbc_driver_manager  <not installed>
altair               5.5.0
azure.identity       <not installed>
boto3                <not installed>
cloudpickle          3.1.1
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               2024.10.0
gevent               <not installed>
google.auth          2.27.0
great_tables         <not installed>
matplotlib           3.10.0
numpy                1.26.4
openpyxl             3.1.5
pandas               2.2.2
pyarrow              17.0.0
pydantic             2.10.6
pyiceberg            <not installed>
sqlalchemy           2.0.37
torch                2.5.1+cu124
xlsx2csv             <not installed>
xlsxwriter           <not installed>

[Hunterlige]

If it can help, the only sql related commit in 1.18 is: #20241

[kosiew]

@nameexhaustion ,

I might have found the fix.

[nameexhaustion]

Thanks @kosiew . For this particular issue, I had already made a lot of progress in a local branch.

If you are looking to contribute, I would recommend looking for accepted issues that do not yet have an assignee - this may also not be accurate so I would also leave a comment in the issue to check if anyone else is working on it.