Metadata scalability: more detail on hashed bins

[joshuagl]

Caveat: I'm reviewing the PEP as a non-expert in attempt to help improve clarity, I hope these comments are useful.

Having read the "Metadata Scalability" section of the PEP and the "Delegate to Hashed Bins" section of the TUF tutorial, I can help but feel there's some detail missing on the hashed bins proposal.

As a reader looking to implement the PEP I'd like to better understand:

• when should the number of bins increase?
• are changes to the number of bins transparent to the client? i.e. does changing the number of bins require some kind of synchronisation between PyPI and its clients?

[joshuagl]

The first question is at least partially answered by @trishankatdatadog in #29, the number of bins should increase when the number of targets increases to 4X the current number.

I think the second question is also answered indirectly - the changes to the number of bins is transparent, the client will be required to download a fresh set of metadata (as though it were a new user) but wouldn't require any explicit code logic or user interaction to do so.

Is my inference correct?

[trishankatdatadog]

@joshuagl yes 💯

[lukpueh]

Fixed with #37