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https://issues.apache.org/jira/browse/CASSANDRA-13657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16083116#comment-16083116
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Kurt Greaves commented on CASSANDRA-13657:
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[~fsander] That seems like it might work, however I'm not sure special casing
liveness info for MV's is a good idea in general. Currently it would work
because we require all MV primary key columns to be {{NOT NULL}}, however this
means if we ever want to remove that restriction we would need to change the
definition of liveness-info again. Generally I'm not keen on having liveness
info mean 2 completely different things depending on the use case. It might be
cheap and effective in this case but I can see how this would be a source of
confusion for anyone trying to work out why their row isn't showing up.
[~jasonstack] what do you think? Will your proposal on CASSANDRA-11500 help
here?
> Materialized Views: Index MV on TTL'ed column produces orphanized view entry
> if another column keeps entry live
> ---------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-13657
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13657
> Project: Cassandra
> Issue Type: Bug
> Components: Materialized Views
> Reporter: Fridtjof Sander
> Assignee: Krishna Dattu Koneru
> Labels: materializedviews, ttl
>
> {noformat}
> CREATE TABLE t (k int, a int, b int, PRIMARY KEY (k));
> CREATE MATERIALIZED VIEW mv AS SELECT * FROM t WHERE k IS NOT NULL AND a IS
> NOT NULL PRIMARY KEY (a, k);
> INSERT INTO t (k) VALUES (1);
> UPDATE t USING TTL 5 SET a = 10 WHERE k = 1;
> UPDATE t SET b = 100 WHERE k = 1;
> SELECT * from t; SELECT * from mv;
> k | a | b
> ---+----+-----
> 1 | 10 | 100
> (1 rows)
> a | k | b
> ----+---+-----
> 10 | 1 | 100
> (1 rows)
> -- 5 seconds later
> SELECT * from t; SELECT * from mv;
> k | a | b
> ---+------+-----
> 1 | null | 100
> (1 rows)
> a | k | b
> ----+---+-----
> 10 | 1 | 100
> (1 rows)
> -- that view entry's liveness-info is (probably) dead, but the entry is kept
> alive by b=100
> DELETE b FROM t WHERE k=1;
> SELECT * from t; SELECT * from mv;
> k | a | b
> ---+------+------
> 1 | null | null
> (1 rows)
> a | k | b
> ----+---+-----
> 10 | 1 | 100
> (1 rows)
> DELETE FROM t WHERE k=1;
> cqlsh:test> SELECT * from t; SELECT * from mv;
> k | a | b
> ---+---+---
> (0 rows)
> a | k | b
> ----+---+-----
> 10 | 1 | 100
> (1 rows)
> -- deleting the base-entry doesn't help, because the view-key can not be
> constructed anymore (a=10 already expired)
> {noformat}
> The problem here is that although the view-entry's liveness-info (probably)
> expired correctly a regular column (`b`) keeps the view-entry live. It should
> have disappeared since it's indexed column (`a`) expired in the corresponding
> base-row. This is pretty severe, since that view-entry is now orphanized.
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