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Aggregating Metrics In-Flight: Challenges, Opportunities

Talkat SREday London 2025 Q3 · 2025-09-18..09-19· [observability]
slides:none on file

Claims that a stream-aggregation collector (VictoriaMetrics agent) can precompute and drop raw series to prevent cardinality explosions, reduce query cost and cut ingestion overhead. Experiment: scraping 130k samples/sec; Prometheus with recording rules uses ~22 GB RAM versus the agent ~5 GB, and a recorded query drops from ~11s to ~1.66s (~8x faster). Agent adds ~1 CPU and ~1 GB when aggregating, supports downsampling, sharding, and prometheus remote_write, but requires careful per-metric design and correct scrape topology.

AI-written summary · about

  1. 0:00Introduction to Aggregating Metrics
  2. 0:23Understanding High Cardinality
  3. 1:27Dealing with High Cardinality
  4. 2:24Relabeling and Recording Rules
  5. 6:32Stream Aggregation Concept
  6. 8:58Stream Aggregation in Practice
  7. 17:32Challenges and Considerations
  8. 18:54Conclusion and Q&A
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