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Andrés de la Peña commented on CASSANDRA-8272:
----------------------------------------------
And [here are the
dtests|https://github.com/riptano/cassandra-dtest/compare/master...adelapena:CASSANDRA-8272]
reproducing the problem. They use 2 replicas instead of 3. Updates use
consistency {{ONE}}, and byteman is used in one of the two nodes to simulate a
long latency during index updates. Insertions and selections use consistency
{{ALL}}.
Cassandra 2.1 doesn't use byteman so, if we are going to fix this version, we
could either add the byteman dependency to 2.1 or modify [the way ccm loads the
byteman jars|https://github.com/pcmanus/ccm/blob/master/ccmlib/node.py#L1609].
> 2ndary indexes can return stale data
> ------------------------------------
>
> Key: CASSANDRA-8272
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8272
> Project: Cassandra
> Issue Type: Bug
> Reporter: Sylvain Lebresne
> Assignee: Andrés de la Peña
> Fix For: 2.1.x
>
>
> When replica return 2ndary index results, it's possible for a single replica
> to return a stale result and that result will be sent back to the user,
> potentially failing the CL contract.
> For instance, consider 3 replicas A, B and C, and the following situation:
> {noformat}
> CREATE TABLE test (k int PRIMARY KEY, v text);
> CREATE INDEX ON test(v);
> INSERT INTO test(k, v) VALUES (0, 'foo');
> {noformat}
> with every replica up to date. Now, suppose that the following queries are
> done at {{QUORUM}}:
> {noformat}
> UPDATE test SET v = 'bar' WHERE k = 0;
> SELECT * FROM test WHERE v = 'foo';
> {noformat}
> then, if A and B acknowledge the insert but C respond to the read before
> having applied the insert, then the now stale result will be returned (since
> C will return it and A or B will return nothing).
> A potential solution would be that when we read a tombstone in the index (and
> provided we make the index inherit the gcGrace of it's parent CF), instead of
> skipping that tombstone, we'd insert in the result a corresponding range
> tombstone.
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