CRITICAL FINDING from previous run:
- getPos() was NEVER called by Parquet/Hadoop!
- This eliminates position tracking mismatch hypothesis
- Bytes are genuinely not reaching our write() method
Added detailed write() logging to track:
- Every write call for .parquet files
- Cumulative totalBytesWritten after each write
- Buffer state during writes
This will show the exact write pattern and reveal:
A) If Parquet writes 762 bytes but only 684 reach us → FSDataOutputStream buffering issue
B) If Parquet only writes 684 bytes → Parquet calculates size incorrectly
C) Number and size of write() calls for a typical Parquet file
Expected patterns:
- Parquet typically writes in chunks: header, data pages, footer
- For small files: might be 2-3 write calls
- Footer should be ~78 bytes if that's what's missing
Next run will show EXACT write sequence.