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Posted to commits@cassandra.apache.org by "Duarte Nunes (JIRA)" <ji...@apache.org> on 2017/04/04 16:24:41 UTC

[jira] [Updated] (CASSANDRA-13409) Materialized Views: View cells are resurrected

     [ https://issues.apache.org/jira/browse/CASSANDRA-13409?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Duarte Nunes updated CASSANDRA-13409:
-------------------------------------
    Summary: Materialized Views: View cells are resurrected  (was: Materialized Views: View cells is resurrected)

> Materialized Views: View cells are resurrected
> ----------------------------------------------
>
>                 Key: CASSANDRA-13409
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-13409
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Duarte Nunes
>
> Consider the following commands, ran against trunk@0f054fee5c:
> {code:xml}
> echo "create keyspace ks WITH replication = {'class': 'SimpleStrategy', 'replication_factor': 1};" | bin/cqlsh
> echo "create table ks.base (p int primary key, v1 int, v2 int) with gc_grace_seconds = 1;" | bin/cqlsh
> echo "create materialized view ks.my_view as select * from ks.base where p is not null and v1 is not null primary key (v1, p);" | bin/cqlsh
> echo "insert into ks.base (p, v1, v2) values (3, 1, 3) using timestamp 1;" | bin/cqlsh
> bin/nodetool flush ks my_view base
> echo "delete from ks.base using timestamp 2 where p = 3;" | bin/cqlsh
> bin/nodetool flush ks my_view base
> echo "insert into ks.base (p, v1) values (3, 1) using timestamp 3;" | bin/cqlsh
> bin/nodetool flush ks my_view base
> echo "select * from ks.my_view;" | bin/cqlsh
>  v1 | p | v2
> ----+---+----
>   1 | 3 |  3
> (1 rows)
> echo "select * from ks.base;" | bin/cqlsh
>  p | v1 | v2
> ---+----+------
>  3 |  1 | null
> (1 rows)
> {code}
> As you can see, this incorrectly brings back cell v2=3. 
> There is one definitive problem and a potential one:
> * Merging rows must be commutative. If a shadowable tombstone is applied after a row tombstone, it will replace that tombstone; if a row marker shadows the shadowable tombstone before the row containing the original data is applied, then any dead cells in said data will be resurrected;
> * Shadowable tombstones shouldn't compact away previous row tombstones or even deleted cells; if the relevant tombstones have been GCed from the base table, then a base table update won't carry them anymore (alongside a newer row marker).



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