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https://issues.apache.org/jira/browse/CASSANDRA-8990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14367775#comment-14367775
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Benedict commented on CASSANDRA-8990:
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This doesn't seem likely to ever be introduced, as it would never be clear to a
query where the data to answer the query should be requested from. Unless you
provided this information on query as well, but this is very burdensome, likely
error prone, and unlikely to be used widely, so not really worth the effort to
support.
Why is it a problem to have multiple keyspaces for different replication
criteria?
You can, as [~philipthompson] says, accept fewer data centres / nodes receiving
the data at write time than you _require_ - but the data will make it to the
left out nodes eventually (and typically very quickly)
> Allow clients to override the DCs the data gets sent to, per write request,
> overriding keyspace settings
> --------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-8990
> URL: https://issues.apache.org/jira/browse/CASSANDRA-8990
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Donald Smith
>
> Currently each keyspace specifies how many replicas to write to each data
> center. In CQL one specifies:
> {noformat}
> WITH replication = {
> 'class': 'NetworkTopologyStrategy',
> 'DC1: '3',
> 'DC2': '3'
> }
> {noformat}
> But in some use cases there's no need to write certain rows to a certain
> datacenter. Requiring the user to create two keyspaces is burdensome and
> complicates code and queries.
> For example, we have global replication of our data to multiple continents.
> But we want the option to send only certain rows globally with certain values
> for certain columns -- e.g., only for users that visited that country).
> Cassandra and CQL should support the ability of client code to specify, on a
> per request basis, that a write should go only to specified data centers.
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