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Score ID implementation

Score IDs exist to dedupe scores when a user re-submits the same scores. This happens frequently with file/ and api/ Import Types, as they typically resubmit the same scores.

If a user only got a score once, we don't want to store it twice.

Sadly, we can't depend on things like timestamps to assert whether or whether not we've saw a score before. Many services alter/tamper their timestamps such that they're unreliable.

Example

E-Amusement IIDX CSVs will change the timestamp of every single score when a new version comes out to the second the user created their new account.

Hashing

The score ID is created by joining the following properties:

  • The userID that got this score
  • The chartID that this score was on
  • All Provided Metrics for this GPT
  • Any Optional Metrics that have been marked as partOfScoreID

and then hashing them with SHA256.

This is then prefixed with T, and returned.

Clobbering

Since a scoreID isn't necessarily all of the possible statistics for a score, it's possible for users to "clobber" their scores, by importing a score without as many pieces of info (i.e. no judgements), then trying to import that same score with judgements later will not work, as the scoreID sees it as a duplicate.

See Clobbering.