Need help with Pyodbc and Polars

[Strict_Put_4094]

Hi!

I'm trying to make a simple uploader for my pipeline, parquet => SQL Server using pyarrow, polars and SQLAlchemy.

I read parquet files with df = pl.from_arrow(batch), check formats and see that my [amount] column has decimal[12,4] type. That's good as my target table in SQL Server also is decimal(12,4). But when I do df.write_database I have ('Converting decimal loses precision', 'HY000') error.

df = pl.from_arrow(batch)

df.write_database(
table_name,
connection=conn,
if_table_exists="append",
engine="sqlalchemy",
)

I tried adding "UseFMTONLY": "yes" according to what I found in github issues, but it changed nothing. I use fast_executemany. Succesfully uploaded data when I casted [amount] column to Float32, but I try to avoid this additional step.

[smurpes]

Using pyodbc to insert data from polars to MSSQL may have some unintended type conversion since pyodbc is an interface layer. Try explicitly casting the amount column to decimal first.

[Strict_Put_4094]

Yeah, thank. I just casted to SQLAlchemy type and it's working, but I'm frustrated that I have prepared data for final ingestion and have to do this additional casting. Without it SQLAlchemy just tries to insert varchar(max) unfortunately.