osu-global-rank-lookup-cache

A memory-based caching layer for beatmap-rank lookups which cannot be easily optimised as a database/SQL level.

Intended to handle queries which iterate over large sections of (already indexed) scores, where the overhead of counting rows becomes an issue.

Environment variables

• DB_HOST: Database host to use when performing lookups (default: localhost)
• DB_USER: Database user to use when performing lookups (default: root)
• USE_NEW_TABLES:
  • When false, scores are looked up from osu_scores_*_high tables, using the ID scheme used by those tables.
  • When true, scores are looked up from the unified scores table, using the ID scheme used by this table.
  • Mandatory, with no default.

Query API

GET /ranklookup?beatmapId={$beatmapId}&score={$score}&rulesetId={$mode}

Parameters

• $beatmapId - The beatmap ID to lookup
• $score - The achieved total score value
• $mode - The ruleset ID (0..3)

Response

Three comma-delimited values:

• An zero-index integer denoting the rank in the leaderboard for the provided score
• The count of all scores on the beatmap's leaderboard
• A boolean indicating whether both preceding counts are accurate or best-effort estimates

TODO

• Currently this is only useful for global leaderboards. Mod filters cannot be applied, for instance.
• More correctly handling top 50 lookups where score collisions are feasible (need to fallback to ID).