Skip to content

Trending / Top-K — Notes#

Functional#

  • Top-K items across windows.
  • Per-region, per-category trends.
  • Spike detection.
  • Safety filters.

Non-functional#

  • Refresh < 60 s.
  • Bounded memory regardless of cardinality.

Trade-offs#

  • Streaming approximate vs batch exact: streaming wins for freshness.
  • Per-window storage keeps explainability.
  • Personalization adds latency; serve global trends + overlay.

Refs#

  • Cormode et al. on CMS / Space-Saving.
  • Twitter trends architecture talks.
  • ByteByteGo "Design top-K service".