Slow writes on Upstash Global: every write goes to the primary region first

Diagnosing slow writes on an Upstash Global database

Symptom

Reads are fast worldwide but writes are slow, especially from regions far from the primary.

Cause

Every write travels to the primary region, gets processed, then replicates out to read regions. There is no local-write path. The docs state the tradeoff openly: Global optimizes read latency and may not suit write-heavy use cases.

Confirm

1. Check which region is primary in the console.

2. Measure write latency from your app region versus from the primary region. If primary-region writes are fast and yours are slow, it is distance, not load.

3. Check your write/read ratio. Above roughly 30% writes, you are in write-heavy territory for this architecture.

Fix options

• Move the primary region to where most writes originate.

• Split the workload: a regional database for the write-heavy parts, Global for the read-heavy parts.

• If writes must be fast globally and consistent, Upstash Global is the wrong tool. Say so early rather than tuning around it.

Verify

Write P99 from the app region drops to near the published same- region baselines after the primary move or the split.

Verified against Upstash global database docs: writes are sent to and processed at the primary region then replicated; the design optimizes READ latency and may not suit WRITE-heavy use cases; pick the primary region where writes happen. Source: https://upstash.com/docs/redis/features/globaldatabase