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From "Duarte Nunes (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-13127) Materialized Views: View row expires too soon
Date Thu, 26 Jan 2017 11:39:24 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15839597#comment-15839597
] 

Duarte Nunes commented on CASSANDRA-13127:
------------------------------------------

I think that the behaviour for an {{UPDATE}} should match that of an {{INSERT}}, since the
latter is probably too late to change.

So, I think a view row's lifetime should be tied to the base row's lifetime, and that's kind
what the code tries to do (the view row liveness can be set to match that of a column not
in the view).

If an operation extends the lifetime of a base row, the corresponding views should be updated.
Similarly, if an update resurrects a base row, the view row should also be resurrected even
if it doesn't include the particular column that triggered it.

> Materialized Views: View row expires too soon
> ---------------------------------------------
>
>                 Key: CASSANDRA-13127
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13127
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Duarte Nunes
>
> Consider the following commands, ran against trunk:
> {code}
> echo "DROP MATERIALIZED VIEW ks.mv; DROP TABLE ks.base;" | bin/cqlsh
> echo "CREATE TABLE ks.base (p int, c int, v int, PRIMARY KEY (p, c));" | bin/cqlsh
> echo "CREATE MATERIALIZED VIEW ks.mv AS SELECT p, c FROM base WHERE p IS NOT NULL AND
c IS NOT NULL PRIMARY KEY (c, p);" | bin/cqlsh
> echo "INSERT INTO ks.base (p, c) VALUES (0, 0) USING TTL 10;" | bin/cqlsh
> # wait for row liveness to get closer to expiration
> sleep 6;
> echo "UPDATE ks.base USING TTL 8 SET v = 0 WHERE p = 0 and c = 0;" | bin/cqlsh
> echo "SELECT p, c, ttl(v) FROM ks.base; SELECT * FROM ks.mv;" | bin/cqlsh
>  p | c | ttl(v)
> ---+---+--------
>  0 | 0 |      7
> (1 rows)
>  c | p
> ---+---
>  0 | 0
> (1 rows)
> # wait for row liveness to expire
> sleep 4;
> echo "SELECT p, c, ttl(v) FROM ks.base; SELECT * FROM ks.mv;" | bin/cqlsh
>  p | c | ttl(v)
> ---+---+--------
>  0 | 0 |      3
> (1 rows)
>  c | p
> ---+---
> (0 rows)
> {code}
> Notice how the view row is removed even though the base row is still live. I would say
this is because in ViewUpdateGenerator#computeLivenessInfoForEntry the TTLs are compared instead
of the expiration times, but I'm not sure I'm getting that far ahead in the code when updating
a column that's not in the view.



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