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Streaming CSV Export ignores CSV_EXPORT settings (encoding=utf-8-sig and sep=';') while ZIP CSV export respects them #45347
Description
CSV_EXPORT settings are not applied consistently across CSV export implementations.
With the following configuration in superset_config.py:
CSV_EXPORT_ = {"encoding": "utf-8-sig", "sep": ";",}
Only ZIP-based CSV exports correctly generate:
UTF-8 with BOM
Semicolon-delimited CSV
However, direct/streaming CSV chart downloads ignore these settings and generate:
UTF-8 without BOM
Comma-separated CSV
This leads to inconsistent export behavior and causes interoperability issues with Microsoft Excel.
Expected Behavior
All CSV export methods should respect the configured values
Actual Behavior
ZIP Export
Produces:
UTF-8 BOM
Semicolon delimiter
Excel opens the file correctly via double-click.
Direct CSV Download (Streaming Export)
Produces:
UTF-8 (without BOM)
Comma delimiter
Excel does not correctly interpret the file when opened via double-click:
Umlauts appear corrupted (e.g. Müller)
Columns may not be split correctly depending on regional settings
Test A: ZIP Export
Export data using a ZIP-based export path.
Result:
delimiter = ;
file encoding = UTF-8-BOM
Excel opens correctly via double-click
umlauts displayed correctly
Test B: Direct CSV Download
Export the same data using the direct CSV download functionality (streaming export).
Result:
delimiter = ,
file encoding = UTF-8 (without BOM)
Excel opens incorrectly via double-click
umlauts appear corrupted (e.g. Müller)
Environment
OS: Ubuntu 24.04
Python: 3.11
Metadata DB: MySQL
Browser: Edge / Chrome
Activity
schizophrenicmaniac commentedon Oct 15, 2026
Hi, I'd like to work on this. On master the streaming export already applies the CSV_EXPORT sep, but _execute_query_and_stream in streaming_export/base.py yields str chunks sent as plain UTF-8, so no BOM. I'd encode them with the configured encoding (BOM only once) and add tests.