~/talk

Aggregating metrics in-flight: challenges and opportunities

Talkat PromCon EU 2024 · 2024-09-11..09-12· [databases]
slides:none on file

High-cardinality is reduced by performing pre-aggregation at ingest: VictoriaMetrics implements Stream Aggregation in the agent and single-node daemon to aggregate by time and labels (matchers + interval + outputs) before forwarding. Example: a 15k-series histogram is aggregated at 5m by resource/verb/bucket and yields comparable quantiles while cutting query time from ~11s to ~1.5s (~8×). Costs: roughly +1 CPU and +1 GB RAM for real-time aggregation; Prometheus used ~4× more memory in the comparison. A custom label compressor cuts worst-case memory up to ~5×; sharding and per-series state handle resets and scaling.

AI-written summary · about

  1. 0:00Introduction and welcome
  2. 1:05What is high cardinality
  3. 3:31Limitations of recording rules
  4. 7:02Chain Prometheus for protection
  5. 8:52Stateless agent vs Prometheus
  6. 9:57Stream aggregation concept
  7. 11:23How stream aggregation works
  8. 13:56Stream aggregation configuration
  9. 15:00Reducing cardinality with stream aggregation
  10. 16:48Downsampling data
  11. 17:32Handling duplication
  12. 18:15Stream aggregation flexibility
  13. 19:19Resource cost comparison
  14. 20:25Memory usage challenges
  15. 22:33Label compression technique
  16. 24:17Scaling stream aggregation
  17. 26:25Summary and benefits
  18. 27:28Q&A session
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