Compare Scenarios

Migration Step 1

Both scenarios define a migration step at this stage. ML Feature Serving Platform: triggered by 'Feature computation logic duplicated across 3+ model serving'. Content Management Platform: triggered by 'Content read API p99 > 100ms during peak traffic; PostgreSQL'.

Migration Step 2

Both scenarios define a migration step at this stage. ML Feature Serving Platform: triggered by 'Regulatory or reproducibility requirement to re-run model pr'. Content Management Platform: triggered by 'Full-text search p99 > 500ms; inability to implement faceted'.

Migration Step 3

Both scenarios define a migration step at this stage. ML Feature Serving Platform: triggered by 'Semantic similarity search recall insufficient from BM25 ful'. Content Management Platform: triggered by 'Month-end content performance reports generating sequential '.

Feature store p99 rising from < 5ms to > 50ms immediately following a model deployment or pod scaling event; Cassandra or PostgreSQL feature store read QPS spiking 10–100x simultaneously with serving fleet restart; feature store connection pool exhaustion visible in application logs during the cold start window; Redis cache hit rate dropping to < 10% for the first 60 seconds after deployment

Tier 1: Cache Cold Start Latency Spike: Simultaneous cache cold start across all serving pods after deployment, converting sequential feature requests into a thundering herd against the backing feature store. Recommended evolution: Implement pre-warming: before a new model version receives traffic, a warm-up job runs inference requests for a representative sample of entity IDs, populating the Redis cache before the pod enters the serving fleet. Use probabilistic early cache refresh (fetch from backing store before TTL expiry when remaining TTL < 20% under high request rate) to prevent simultaneous TTL expiry on hot features. Stagger deployment rollout: deploy 10% of pods, wait for cache warm, then proceed to the next 10%. .

Model performance metrics (precision, recall, AUC) degrading without a corresponding input distribution shift; ClickHouse drift dashboard showing feature value distributions served online diverging from training population distributions; explicit skew audit (comparing offline training feature values against replayed online feature values for the same entity at the same timestamp) showing systematic differences in specific features

Tier 2: Training-Serving Skew Detection: Feature computation logic divergence between the offline training pipeline and the online serving pipeline: a feature transformation applied in training is not applied identically in serving. Recommended evolution: Enforce a single feature computation function registered per feature in a shared feature registry, executed by both the online pipeline and the offline training pipeline. The two paths must use the same code, not independently maintained implementations. Implement a skew monitoring job that computes a random sample of features using both paths and alerts on distribution divergence above a threshold. .

PostgreSQL pg_stat_statements showing > 10 distinct query patterns with high call counts from the content list API path; database queries per second growing linearly with API request rate for content list endpoints (should be sub-linear with proper batch fetching); p99 for content list API > 200ms during moderate traffic

Tier 1: N+1 Query Amplification: ORM-level N+1 patterns in content relationship traversal: author fetch, category fetch, related content fetch as independent queries per article. Recommended evolution: Audit every content API response with query logging enabled and count queries per request for each content type; implement eager loading for all included relationships (JOIN for 1:1, IN-clause batch for 1:N); validate that content list endpoints produce a fixed number of queries regardless of list size (O(1) queries, not O(N)); add a query count assertion to integration tests for content list endpoints to prevent regression .

PostgreSQL read replica CPU spike correlated exactly with publish events; Redis cache hit rate dropping to near 0% immediately after publish for popular content; content API p99 spiking from < 20ms to > 500ms during the 1–3 second window after a high-traffic content item is published

Tier 2: Cache Invalidation Thundering Herd: Cache key deletion on publish triggering simultaneous cache miss stampede for all concurrent readers of popular content. Recommended evolution: Implement cache-aside with probabilistic early expiration (PER): before the cache TTL expires, a fraction of reads proactively refresh the cache value while other reads continue serving the cached value; this eliminates the hard expiry boundary that causes simultaneous misses; alternatively, on publish, write the new content value directly into the cache key before invalidating the old one (update-in-place rather than delete-and-miss) to eliminate the invalidation gap .