Labs
Each lab takes under an hour on a laptop and turns a claim from this mechanism into something you can see or measure. Splittability: CSV with quoted newlines versus NDJSON and The footer pays for column skipping need Python with pyarrow (pip install pyarrow). The numbers you get will differ from the ones quoted; the pattern should not.
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Splittability: CSV with quoted newlines versus NDJSON
Split a CSV with quoted newlines and an NDJSON file at random byte offsets and count the records each split breaks.
Break itPython - 2
The footer pays for column skipping
A 200-column Parquet file: read 3 columns against all 200, read the footer statistics, then append bytes after the footer.
MeasurePython with PyArrow - 3
The six interop hazards
Write values one way and read them another: encoding, decimals as floats, null/empty/missing, zoneless times, int32 overflow, collation.
Break itPython with NumPy - 4
Idempotency: a webhook that retries
A charging server that is sometimes slow and a client that retries on timeout: charges with and without an Idempotency-Key.
Real systemPython - 5
Offset versus keyset pagination, under writes
Page through a million SQLite rows with OFFSET and with a keyset predicate: time at page 10,000, and duplicates after one insert.
MeasurePython - 6
File drop with manifest as commit
Publish file batches with stage, checksum, atomic rename and manifest last; break them three ways; then delete a batch with no schedule.
Break itPython