ASF GitHub Bot updated CASSANDRA-8272:
    Labels: pull-request-available  (was: )

> 2ndary indexes can return stale data
> ------------------------------------
>                 Key: CASSANDRA-8272
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8272
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Feature/2i Index
>            Reporter: Sylvain Lebresne
>            Assignee: Andres de la Peña
>            Priority: Normal
>              Labels: pull-request-available
>             Fix For: 3.0.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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