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From "ZhaoYang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-13127) Materialized Views: View row expires too soon
Date Mon, 17 Jul 2017 08:41:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-13127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16089502#comment-16089502
] 

ZhaoYang commented on CASSANDRA-13127:
--------------------------------------

Updated the patch. Now MV should handle partial update properly, UPDATE semantic is now same
as INSERT which means as long as data exists in base, the data should exist in view.

It introduces {{Shadowable-LivenessInfo}}.  if {{livenessInfo}} is {{shadowable}} and {{not
live}}, all columns in the row are considered deleted.  

And this {{Shadowable-LivenessInfo}} can be further extended for CASSANDRA-11500 to solve
view timestamp tie.

> Materialized Views: View row expires too soon
> ---------------------------------------------
>
>                 Key: CASSANDRA-13127
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13127
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Local Write-Read Paths, Materialized Views
>            Reporter: Duarte Nunes
>            Assignee: ZhaoYang
>
> 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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