Fix DuckDB bulk_insert failing when quoted CSV cells fall outside sniffer sample#64
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martinv13 merged 3 commits intoJun 17, 2026
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…ffer sample (cre-dev#62) DuckDB's read_csv sniffer only examines the first ~20 480 rows; if none are quoted, it sets quote=(empty) and then errors on any later quoted cell with a column-count mismatch. Passing quote='"' explicitly bypasses auto-detection. Adds a regression test that inserts 25 000 plain rows followed by one row whose value contains a comma (triggering csv.writer quoting). Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Makes the RFC 4180 doubling behaviour explicit rather than relying on DuckDB defaulting escape to the same char as quote. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Fixes #62.
read_csvsniffer examines only the first ~20 480 rows as its sample. If no quoted cells appear in that sample, it setsquote=(empty)— meaning it treats"as an ordinary character.join-transformed columns produce a value containing a comma (e.g."val,ue",other), Python'scsv.writerwraps the whole cell in outer quotes. Any such cell beyond row ~20 480 would cause a column-count mismatch and anInvalid Input Error.quote='"'explicitly toread_csvinDuckDBDialect.bulk_insert, bypassing auto-detection entirely.Test plan
test_duckdb_bulk_insert_quoted_csv_field_after_large_unquoted_sampleinserts 25 000 plain rows followed by one row whoselabelcontains a comma; verifies all rows are read back correctly.test_bulk_insert.pytests still pass.TZ="Europe/Paris" DB_STRING="duckdb:///:memory:" python -m pytest🤖 Generated with Claude Code