Aleksey Yeschenko created CASSANDRA-6507:
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Summary: counters++ get rid of logical clock in global shards
Key: CASSANDRA-6507
URL: https://issues.apache.org/jira/browse/CASSANDRA-6507
Project: Cassandra
Issue Type: Improvement
Reporter: Aleksey Yeschenko
Assignee: Aleksey Yeschenko
Priority: Minor
Fix For: 2.1
In CASSANDRA-6504 the global shards still follow the {count, logical clock}
pattern of the legacy shards. We could store the {increments, decrements} tuple
in the shard instead, and for reconcile, instead of relying on the logical
clock, pick the largest value of `increments` and `decrements` of the two
shards, and use that.
E.g., shard1: {2000, 1001} (total 999), shard2: {2001, 1000} (total 1001).
reconciled = {max(2000, 2001), max(1001, 1000)} = {2001, 1001} (total 1000).
While scenarios like this generally shouldn't happen post CASSANDRA-6504, this
change costs us nothing, and makes issues like CASSANDRA-4417 theoretically
impossible . This also makes our new implementation directly follow the
http://hal.inria.fr/docs/00/55/55/88/PDF/techreport.pdf white paper.
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