Added logging to show:
1. totalPosition: Total bytes ever written to stream
2. buffer.position(): Bytes still in buffer before flush
3. finalPosition: Position after flush completes
This will reveal if:
- Parquet wrote 1338 bytes → position should be 1338
- Only 1260 bytes reached write() → position would be 1260
- 78 bytes stuck in buffer → buffer.position() would be 78
Expected output:
close: path=...parquet totalPosition=1338 buffer.position()=78
→ Shows 78 bytes in buffer need flushing
OR:
close: path=...parquet totalPosition=1260 buffer.position()=0
→ Shows Parquet never wrote the 78 bytes!