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https://issues.apache.org/jira/browse/CASSANDRA-10226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14723996#comment-14723996
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Tyler Hobbs commented on CASSANDRA-10226:
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bq. I'm assuming you will continue to filter out nulls?
Yes, the current {{IS NOT NULL}} restrictions will continue to apply for now.
bq. Also, how is this any different than a secondary index?
The two main differences are 1) that it doesn't require a scatter-gather query,
and 2) only a single read needs to be executed instead of reading the index
table and then reading multiple keys from the base table. Is that what you're
asking, or am I missing something?
> Support multiple non-PK cols in MV clustering key when partition key is shared
> ------------------------------------------------------------------------------
>
> Key: CASSANDRA-10226
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10226
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Tyler Hobbs
> Assignee: Tyler Hobbs
> Labels: materializedviews
> Fix For: 3.0.0 rc1
>
>
> This issue is similar to CASSANDRA-9928, but with one key limitation: the MV
> partition key must match the base table's partition key. This limitation
> results in the base replica always pairing with itself as the MV replica.
> Because of this pairing, if the base replica is lost, any MV rows that would
> otherwise be ambiguous are also lost. This allows us to avoid the problem
> described in 9928 of not knowing which MV row to delete.
> Although this limitation has the potential to be a bit confusing for users, I
> believe this improvement is still worthwhile because:
> * The base table's partition key will often be a good choice for the MV
> partition key as well. I expect it to be common for users to partition data
> the same way, but use a different clustering order to optimize for (or allow
> for) different queries.
> * It may take a long time to solve the problems presented in 9928 in general
> (if we can solve them at all). On the other hand, this is straightforward
> and is a significant improvement to the usability of MVs.
> I have a minimal prototype of this that works well, so I should be able to
> upload a patch with thorough tests within the next few days.
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