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https://issues.apache.org/jira/browse/CASSANDRA-5998?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Ellis resolved CASSANDRA-5998.
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Resolution: Duplicate
UDF is the right way to do this now.
> Filters
> -------
>
> Key: CASSANDRA-5998
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5998
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Matt Stump
> Original Estimate: 120h
> Remaining Estimate: 120h
>
> As a counterpart to the functionality provided in triggers it is desirable to
> filter/mutate query results utilizing a user specified classes.
> Some example use cases include:
> Row or cell level permissions
> Ad-hoc aggregation or filtering of column values
> Proposed changes include the following:
> * Alter CF metadata to allow the specification of filter classes and options.
> * Modification of the CQL(3) grammar and addition of create/drop filter
> statements to allow the specification of filter classes.
> * Move cassandara/triggers/CustomClassLoader.java to
> cassandara/CustomClassLoader.java and use the class loader for both triggers
> and filters.
> * The addition of the following classes: FilterDefinition, FilterExecuter,
> and IFilter.
> * Modification of StorageProxy::fetchRows, such that if the CF has a filter
> specified, rows returned by the result set are run first through the filter
> which has the authority of either dropping or modifying rows from the result
> set. If no filter is specified then no filter will be invoked.
> * In order to enable the row/cell level authorization use case
> StorageProxy::fetchRows must be modified to also require the ClientState.
> Risks:
> My main concern with the current proposal is that the dependency on
> ClientState in order to satisfy the cell/row level permissions use case will
> introduce tight coupling between StorageProxy and ClientState. Another
> possibility yet to be investigated is to pass ClientState to the filter when
> the filter class is instantiated.
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