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From "Kurt Greaves (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-13066) Fast streaming with materialized views
Date Wed, 12 Jul 2017 00:32:00 GMT


Kurt Greaves commented on CASSANDRA-13066:

Done. Wouldn't say this makes it a _requirement_ of an append-only MV's release but at least
it's easier to keep track of in the scheme of things.

> Fast streaming with materialized views
> --------------------------------------
>                 Key: CASSANDRA-13066
>                 URL:
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: Materialized Views, Streaming and Messaging
>            Reporter: Benjamin Roth
>            Assignee: Benjamin Roth
>             Fix For: 4.0
> I propose adding a configuration option to send streams of tables with MVs not through
the regular write path.
> This may be either a global option or better a CF option.
> Background:
> A repair of a CF with an MV that is much out of sync creates many streams. These streams
all go through the regular write path to assert local consistency of the MV. This again causes
a read before write for every single mutation which again puts a lot of pressure on the node
- much more than simply streaming the SSTable down.
> In some cases this can be avoided. Instead of only repairing the base table, all base
+ mv tables would have to be repaired. But this can break eventual consistency between base
table and MV. The proposed behaviour is always safe, when having append-only MVs. It also
works when using CL_QUORUM writes but it cannot be absolutely guaranteed, that a quorum write
is applied atomically, so this can also lead to inconsistencies, if a quorum write is started
but one node dies in the middle of a request.
> So, this proposal can help a lot in some situations but also can break consistency in
others. That's why it should be left upon the operator if that behaviour is appropriate for
individual use cases.
> This issue came up here:

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