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https://issues.apache.org/jira/browse/CASSANDRA-1263?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12923119#action_12923119
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Jon Hermes commented on CASSANDRA-1263:
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So on keyspace instantiation, I expect some set of opts for a given strategy to
exist, otherwise calling getRF() will explode. Because user-def strats can
require arbitrary opts, I can't easily verify that they exist*, and I can't
guarantee that system_create_keyspace() will not explode (which is a
non-desired side effect).
Furthermore, I have to call getRF() is every place in the code that we ask for
the instance RF, and I can't guarantee that getRF() is non-trivial (and it runs
in tight loops). Caching the getRF() call is a hefty chunk of code, and then I
need to reset the cached value if the KSMD changes during runtime, which is
another hefty chunk of code.
*It is possible to make every strat implement an interface method for
`List<String> returnRequiredOpts()`.
> Push replication factor down to the replication strategy
> --------------------------------------------------------
>
> Key: CASSANDRA-1263
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1263
> Project: Cassandra
> Issue Type: Task
> Components: Core
> Reporter: Jeremy Hanna
> Assignee: Jon Hermes
> Priority: Minor
> Fix For: 0.7.0
>
>
> Currently the replication factor is in the keyspace metadata. As we've added
> the datacenter shard strategy, the replication factor becomes more computed
> by the replication strategy. It seems reasonable to therefore push the
> replication factor for the keyspace down to the replication strategy so that
> it can be handled in one place.
> This adds on the work being done in CASSANDRA-1066 since that ticket will
> make the replication strategy a member variable of keyspace metadata instead
> of just a quasi singleton giving the replication strategy state for each
> keyspace. That makes it able to have the replication factor.
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