Fail to query DataFrame with Decimal with sum, treated as string

[jovezhong]

Please make sure that the version you're using is still supported (you can find the list here).

You have to provide the following information whenever possible.

Describe what's wrong

A clear and concise description of what works not as it is supposed to.

A link to reproducer in https://fiddle.clickhouse.com/.

Does it reproduce on the most recent release?

The list of releases

Enable crash reporting

Change "enabled" to true in "send_crash_reports" section in config.xml:

<send_crash_reports>
        <!-- Changing <enabled> to true allows sending crash reports to -->
        <!-- the ClickHouse core developers team via Sentry https://sentry.io -->
        <enabled>false</enabled>

How to reproduce

• Which ClickHouse server version to use
  chdb 3.1.2
• Which interface to use, if it matters
  Python
• Non-default settings, if any
• CREATE TABLE statements for all tables involved

items=chdb.query("select * from file('costco_details.csv','CSV','ts_str String, total_amount Decimal32(2), warehouse String,item_name String,item_code String,item_amount Decimal32(2),item_note String,subtotal Decimal32(2),tax Decimal32(2),payment_method String, total_items_sold Int8, savings Decimal32(2)') settings input_format_csv_skip_first_lines = 1",output_format="DataFrame")

chdb.query("select parseDateTimeBestEffort(ts_str,3,'UTC') as ts, count(),sum(item_amount) from Python(items) group by 1",output_format="DataFrame")

• Sample data for all these tables, use clickhouse-obfuscator if necessary
• Queries to run that lead to an unexpected result

Expected behavior

A clear and concise description of what you expected to happen.
column in Decimal can be aggregated with sum

Error message and/or stacktrace

If applicable, add screenshots to help explain your problem.

Error
File "/Users/jove/Dev/marimo_notebooks/.venv/lib/python3.13/site-packages/chdb/init.py", line 103, in query
res = conn.query(sql, output_format)
RuntimeError: Code: 43. DB::Exception: Illegal type String of argument for aggregate function sum. (ILLEGAL_TYPE_OF_ARGUMENT)

Additional context

Add any other context about the problem here.

[jovezhong]

Sorry I cannot share the sample data. I encountered such issue while writing this blog https://www.linkedin.com/pulse/lets-overkill-use-mcp-chdb-understand-your-costco-spending-jove-zhong-afrwc Workaround is to define the item amount as Float32, not Decimal32(2)