furcypin / duckdb-wasm-minimal-bug-example

Reproduction of a weird bug in duckdb-wasm

Installation

• Run ./start_node.js to start a local nodejs server.
• Open a browser to localhost:8001
• In the browser, open WORKS.html. It works.
• In the browser, open DOES_NOT_WORK.html. It does not work and fails with the following error:

Uncaught RuntimeError: null function or function signature mismatch
    at U.onMessage (async_bindings.ts:150:23)

The only difference between WORKS.html and DOES_NOT_WORK.html is that they load different files.

• WORKS.html loads diff_without_index.db
• DOES_NOT_WORK.html loads diff_with_index.db

The two files were generated exactly the same way in Python, the only difference is that when generating diff_with_index.db, I created an index on the table sample_0 with the following query (using the Python API):

conn.execute("""
    CREATE UNIQUE INDEX sample_0_idx ON sample_0 (__SAMPLE_ID__);
""")

Investigation

I also added a Python script to showcase that the problems seems to come from duckdb-wasm itself, not duckdb.

It only require to have the duckdb Python package installed. Personnaly I use Python Poetry but any setup (virtualenv + pip or else) should be fine.

To use it with Poetry, just run:

• poetry env use 3.8
• poetry update
• poetry run python WORKS.py works (and loads diff_without_index.db)
• poetry run python WORKS_TOO.py works too (and loads diff_with_index.db)

About the data

Nothing to worry about: the data files were generated from a French OpenData dataset:

• https://www.prix-carburants.gouv.fr/rubrique/opendata/
• https://data.economie.gouv.fr/explore/dataset/prix-des-carburants-en-france-flux-instantane-v2/export/

I'm using them to showcase an example for my data-diff tool which use duckdb-wasm to build the html report: https://furcypin.github.io/spark-frame/use_cases/comparing_dataframes/#french-gas-price