[
https://issues.apache.org/jira/browse/CASSANDRA-8273?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15266284#comment-15266284
]
Robert Stupp commented on CASSANDRA-8273:
-----------------------------------------
Maybe we could introduce an {{ALLOW CONSISTENT FILTERING}} option to perform
filtering on the coordinator, if one cannot live with stale data.
> Allow filtering queries can return stale data
> ---------------------------------------------
>
> Key: CASSANDRA-8273
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8273
> Project: Cassandra
> Issue Type: Bug
> Reporter: Sylvain Lebresne
>
> Data filtering is done replica side. That means that a single replica with
> stale data may make the whole query return that stale data.
> For instance, consider 3 replicas A, B and C, and the following situation:
> {noformat}
> CREATE TABLE test (k int PRIMARY KEY, v1 text, v2 int);
> CREATE INDEX ON test(v1);
> INSERT INTO test(k, v1, v2) VALUES (0, 'foo', 1);
> {noformat}
> with every replica up to date. Now, suppose that the following queries are
> done at {{QUORUM}}:
> {noformat}
> UPDATE test SET v2 = 2 WHERE k = 0;
> SELECT * FROM test WHERE v1 = 'foo' AND v2 = 1;
> {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. Let's
> note that this is a problem related to filtering, not 2ndary indexes.
> This issue share similarity with CASSANDRA-8272 but contrarily to that former
> issue, I'm not sure how to fix it. Obviously, moving the filtering to the
> coordinator would remove that problem, but doing so would, on top of not
> being trivial to implmenent, have serious performance impact since we can't
> know in advance how much data will be filtered and we may have to redo query
> to replica multiple times.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
