Compare Scenarios

Migration Step 1

Both scenarios define a migration step at this stage. Read-Heavy SaaS API: triggered by 'Connection pool exhaustion or p99 read latency > 200ms under'. Developer Tools Platform: triggered by 'First noisy neighbor incident where one tenant's CI burst de'.

Migration Step 2

Both scenarios define a migration step at this stage. Read-Heavy SaaS API: triggered by 'Primary CPU > 70% during peak read hours'. Developer Tools Platform: triggered by 'Kafka publish failures rolling back pipeline completion tran'.

Migration Step 3

Developer Tools Platform has a defined migration; Read-Heavy SaaS API does not at this stage.

p99 database latency rising; connection wait queue growing; requests timing out with "too many connections" or pool queue full errors

Tier 1: Connection Exhaustion: Database connection pool saturated or max_connections exceeded. Recommended evolution: Add PgBouncer connection pooler in transaction mode.

Database CPU > 80% sustained; read query p99 rising; cache miss rate stable but overall latency increasing

Tier 2: Read Throughput Ceiling: Single PostgreSQL primary saturated with read traffic. Recommended evolution: Add one or more streaming read replicas; implement lag-aware replica routing.

Redis job queue depth > 1000 correlated with a single tenant identifier; other tenants reporting p99 job start time > 60 seconds; tenant-level queue metrics showing one tenant holding > 50% of in-flight worker slots

Tier 1: Job Queue Tenant Noisy Neighbor: Shared Redis queue with shared worker pool allowing one tenant to monopolize available capacity. Recommended evolution: Implement per-tenant queue lanes in Redis (separate key namespaces per tenant, e.g., jobs:{tenant_id}:{priority}); implement a weighted fair scheduler at the worker dispatch layer that reads from tenant queues in round-robin order with priority weighting; cap the number of concurrently executing jobs per tenant to the tenant's quota, not to the total available worker count .

DDL migration duration > 10s on pipeline_runs, jobs, or artifacts tables; migration deployment causing timeout errors for active CI pipeline API calls during the deployment window; pg_locks showing AccessExclusiveLock held by ALTER TABLE statement

Tier 2: PostgreSQL Schema Migration Lock: High-volume tables requiring locking DDL changes during deployments with concurrent tenant activity. Recommended evolution: Adopt zero-downtime migration patterns exclusively: add columns with nullable defaults first (no table lock in PostgreSQL 11+), then backfill, then add constraints via NOT VALID followed by VALIDATE CONSTRAINT in a separate transaction; use pg_repack for table rewrites; never run concurrent index creation without CONCURRENTLY on any table with > 1M rows .