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When normalize_rows_to_columns=true, the Python csv.reader is used instead of DuckDB's read_csv. If the CSV file has a UTF-8 BOM (\xef\xbb\xbf), the BOM bytes would be included in the first field. Use utf-8-sig encoding which automatically strips the BOM if present, while being identical to utf-8 for files without BOM. This fixes reading of CSV files from sources like MEF Dipartimento Finanze that emit BOM-encoded CSVs.
Gabrymi93
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Problem
When , the Python is used instead of DuckDB's . If the CSV file has a UTF-8 BOM (), the BOM bytes are included in the first field, which can cause issues.
Some data sources (e.g., MEF Dipartimento Finanze) emit CSV files with BOM encoding.
Fix
Use encoding in which automatically strips the BOM if present, while being identical to for files without BOM.
Testing