Andrew Sherman created IMPALA-13408:
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             Summary:  use a specific flag for the topic prefix cluster 
identifier.
                 Key: IMPALA-13408
                 URL: https://issues.apache.org/jira/browse/IMPALA-13408
             Project: IMPALA
          Issue Type: Bug
          Components: Backend
    Affects Versions: Impala 4.5.0
            Reporter: Andrew Sherman
            Assignee: Andrew Sherman


The cluster_id flag was introduced in IMPALA-12426 to identify Impala clusters 
in systems where a single query_log table could be shared.

In IMPALA-13208 the cluster_id flag was reused as a prefix to topic names for 
backend membership, to allow sub-clusters of backends within a Statstore 
service.

There have been some problems with the interaction of these two usages. An 
important difference is that the query_log cluster_id must be set only on 
coordinators, whereas the topic prefix cluster_id must be set simultaneously on 
coordinators, executors, and admission daemons (if present). If a system is 
started with cluster_id set only on coordinators then there are split-brain 
problems where coordinators and executors are tracked in different topics.

In addition, the query_log cluster_id is more likely to be user-settable as it 
is used for data in query_log which will be read by humans, who may want to 
write queries selecting data from their ‘production’ or ‘dev’ clusters.

Avoid these problems by using a separate flag for the  topic prefix cluster_id, 
perhaps ‘cluster_membership_topic_id’



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