Benedict created CASSANDRA-14777:
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Summary: ReadExecutor cannot upgrade digest to data request
Key: CASSANDRA-14777
URL: https://issues.apache.org/jira/browse/CASSANDRA-14777
Project: Cassandra
Issue Type: Improvement
Components: Coordination
Reporter: Benedict
ReadExecutor cannot send a request to any node it has already contacted, as the
accounting cannot handle multiple responses from the same host. In fact, any
bug wherein a host somehow responded twice anyway would lead to a consistency
level breakage.
The main problem incurred here is that if we receive no data response, we may
not be able to speculate to obtain another one, particularly if only transient
replicas remain to be contacted. We might also be able to avoid speculating
two data requests in ‘always’ speculating, also, as presumably this was to
ensure the same problem was not encountered (wherein by ‘always’ speculating
upfront, we could not recover from our only data response not arriving).
Ideally, we would maintain a map of endpoint->responses, and simply use the
‘best’ response we have for each endpoint, and only count the first response
towards our consistency counter.
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