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I have a couchdb in a cluster setup. 3 nodes, all shards on all nodes and W = 2. We have code to create a document in couchdb and read it back from a view. However, the view returns no corresponding data intermittently. The data is there after we check couchdb directly. So, my question is that why the third nodes taking so long to write a value and how long should I expect the write latency to be?

Thanks in advance.

leiz
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1 Answers1

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If you query a view and not use stale parameter, views are supposed to always return fresh data. A view will first gets itself updated to the database, and then returns results for your query.

A view can get results from any node. If you query a view, and don't get expected fresh data, it means that the updates are not yet available on the node used.

If a write a document with W =2, than at least two nodes out of three should successfully update this document. And if all nodes are up, internal synchronization between nodes, within milliseconds or seconds should bring updates to all nodes. So the latency should be just several seconds.

How long was the latency that you experienced? Was your view finally able to produce the expected results after this latency?

Mayya Sharipova
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  • Thanks for your answer. We don't really know how to test the latency between the nodes communication. We just set up this new environment, so nothing is really running on it. The view eventually gives the right value. – leiz Aug 14 '17 at 02:29
  • If latency is seconds, then I consider this is way too slow. – leiz Aug 14 '17 at 02:41