Publish and consume Google Pub/Sub messages with ordering keys
domain: cloud.google.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Create a Pub/Sub topic with message ordering enabled; this cannot be changed after creation
Create a subscription on the topic with enable_message_ordering=true
When publishing, set the ordering_key field on each PubsubMessage to the value that should be sequenced together
Use a publisher client that supports ordering and ensure messages with the same ordering key are published from the same publisher client instance
Consume messages sequentially per ordering key; acknowledge each message before the next one for the same key is delivered
Known gotchas
If a publish fails for a given ordering key, the publisher must call resumePublish(orderingKey) before further messages on that key are accepted, or subsequent publishes are rejected
Ordering is only guaranteed within a single region; cross-region Pub/Sub does not preserve ordering
High-throughput scenarios with many distinct ordering keys can reduce parallelism; model ordering keys at the right granularity to balance ordering and throughput
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