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https://issues.apache.org/jira/browse/KAFKA-6249?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias J. Sax resolved KAFKA-6249.
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    Resolution: Duplicate

> Interactive query downtime when node goes down even with standby replicas
> -------------------------------------------------------------------------
>
>                 Key: KAFKA-6249
>                 URL: https://issues.apache.org/jira/browse/KAFKA-6249
>             Project: Kafka
>          Issue Type: Bug
>          Components: streams
>    Affects Versions: 1.0.0
>            Reporter: Charles Crain
>
> In a multi-node Kafka Streams application that uses interactive queries, the 
> queryable store will become unavailable (throw InvalidStateStoreException) 
> for up to several minutes when a node goes down.  This happens regardless of 
> how many nodes are in the application as well as how many standby replicas 
> are configured.
> My expectation is that if a standby replica is present, that the interactive 
> query would fail over to the live replica immediately causing negligible 
> downtime for interactive queries.  Instead, what appears to happen is that 
> the queryable store is down for however long it takes for the nodes to 
> completely rebalance (this takes a few minutes for a couple GB of total data 
> in the queryable store's backing topic).
> I am filing this as a bug, realizing that it may in fact be a feature 
> request.  However, until there is a way we can use interactive queries with 
> minimal (~zero) downtime on node failure, we are having to entertain other 
> strategies for serving queries (e.g. manually materializing the topic to an 
> external resilient store such as Cassandra) in order to meet our SLAs.
> If there is a way to minimize the downtime of interactive queries on node 
> failure that I am missing, I would like to know what it is.
> Our team is super-enthusiastic about Kafka Streams and we're keen to use it 
> for just about everything!  This is our only major roadblock.



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