Pub/Sub Best Practices
Pub/Sub Best Practices: Features
Publishing, subscribing, feature, latency, client-library, and testing trade-offs
Six 2023 episodes explain Pub/Sub trade-offs in batching, retries, ordering, flow control, retention, regional placement, and testing. Recommendations reflect the client libraries and service behavior discussed in that series.
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Pub/Sub can retain messages for later processing, replay messages after a mistake, and route undeliverable messages to a separate topic. Chloe explains the controls behind those recovery paths, along with push delivery and limits on where messages are stored.
Key points
- Push can fit constrained or shared receivers: The episode suggests it when subscriber code cannot use a client, outgoing requests are unavailable, or one endpoint receives from several topics and subscriptions 00:00–01:04(opens in a new tab).
- Seek changes which messages need delivery: Seeking to a snapshot or timestamp can mark previously acknowledged messages as unacknowledged so Pub/Sub delivers them again. Seeking to a future timestamp instead clears the unacknowledged backlog 00:00–02:06(opens in a new tab).
- Retention keeps messages available: Topic retention stores messages even before a consumer is ready. Subscription retention can keep messages after acknowledgement. The episode's maxima—31 days for topics and seven days for subscriptions—are 2023 limits 01:04–02:06(opens in a new tab).
- Dead-letter topics isolate undeliverable messages: Pub/Sub forwards those messages to a separate topic. Chloe describes recovery options: move them back to the original topic through a Dataflow pipeline, or change a consumer pipeline to read both topics 02:06–03:10(opens in a new tab).
- A storage policy controls persistence location: It restricts where topic messages are stored regardless of publish-request origin; the source does not claim that it fixes processing location or every network and residency concern 02:06–03:10(opens in a new tab).
Full video: https://www.youtube.com/watch?v=2-8wgvanQHI(opens in a new tab)