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https://issues.apache.org/jira/browse/CASSANDRA-13657?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16085063#comment-16085063
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Kurt Greaves commented on CASSANDRA-13657:
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[~fsander]
bq. From my understanding that is not possible, since all PK parts must be NOT
NULL
That is correct, going back to the original implementation there was a lot of
discussion about this and it was decided to enforce all PK parts to be NOT
NULL, to simplify the implementation for 3.0. However at the time it was never
confirmed whether it would be a strict requirement for the future. Hinted at as
a hard problem to solve, but not ruled out entirely. See
[original|https://issues.apache.org/jira/browse/CASSANDRA-6477?focusedCommentId=14627670&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14627670]
ticket and comments surrounding it:
My concern is that tying MV "components" to base "components" makes it more
difficult to lift the {{IS NOT NULL}} requirement. That requirement might be
perfectly fine, but I think a decision needs to be made beforehand if that is
the path we'll go down with MV's.
This really applies in general to MV bugs/existing tickets however (and is
probably not the only issue), as it likely has an impact on how we fix all of
them (i.e do we cram more "features" in to fix the bugs, or do we aim to
re-write this stuff to make Cassandra more view-friendly).
bq. The way I see it, a view-row's liveness is actually different from an
ordinary row's liveness. So, it makes sense to have code representing that
difference, instead of squeezing the new definition into the old mechanism and
constantly having to patch stuff left and right.
To clarify - you're totally correct, however I'm more asking the question of
"do we want that to always be the case?". Personally I wouldn't mind as it
simplifies things (especially this case), but I'm certainly no authority on the
matter.
Anyway, it would be good to get more people in on the discussion (and hopefully
some of the original developers) so I'll ping the ML.
> 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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