Richard Low created CASSANDRA-10726:
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Summary: Read repair inserts should not be blocking
Key: CASSANDRA-10726
URL: https://issues.apache.org/jira/browse/CASSANDRA-10726
Project: Cassandra
Issue Type: Improvement
Components: Coordination
Reporter: Richard Low
Today, if there’s a digest mismatch in a foreground read repair, the insert to
update out of date replicas is blocking. This means, if it fails, the read
fails with a timeout. If a node is dropping writes (maybe it is overloaded or
the mutation stage is backed up for some other reason), all reads to a replica
set could fail. Further, replicas dropping writes get more out of sync so will
require more read repair.
The comment on the code for why the writes are blocking is:
{code}
// wait for the repair writes to be acknowledged, to minimize impact on any
replica that's
// behind on writes in case the out-of-sync row is read multiple times in quick
succession
{code}
but the bad side effect is that reads timeout. Either the writes should not be
blocking or we should return success for the read even if the write times out.
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