Chunkstore update with a Passthrough chunker duplicates segments when converting from Python 2.7->3

[TomTaylorLondon]

Arctic Version

# All

Arctic Store

# ChunkStore

Platform and version

2.7 vs 3

Description of problem and/or code sample that reproduces the issue

Segments are duplicated when:

• Data is written in Python 2.7 using Chunkstore Passthrough chunker
• Data is updated in Python 3

Root cause is:

• start_date/end_date is b'NA' which in Python 2.7 == str('NA') but in Python 3.0 != str('NA')

Possible fixes:

1. Remove support for update with Passthrough chunker. It's unclear to me what functionality it provides above a write(..)
2. Infer if start_date/end_date is str('NA') or bytes('NA') in python 3 and maintain backwards compatibility

@bmoscon thoughts?

[TomTaylorLondon]

https://api.mongodb.com/python/current/python3.html indicates we will most likely have the reverse issue too

[bmoscon]

@TomTaylorLondon if you want the history on the passthrough chunker, we can talk offline. Someone internal needed it to write non timeseries data. It may or not be needed anymore.