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https://issues.apache.org/jira/browse/CASSANDRA-11458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel=15230988#comment-15230988
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Henry Manasseh edited comment on CASSANDRA-11458 at 4/7/16 8:57 PM:
I think your new feature CASSANDRA-11295 provides what I need. I already have a
dummy custom index and a hack which removes the custom expression and injects
my own expression subclass which actually works... but I'll plan on
re-implementing based on the new UserExpression class.
was (Author: henryman):
I think your new feature CASSANDRA-11295 provides what I need. I already have a
dummy custom index and a hack which removes the custom expression and injects
my own expression subclass which actually works... but I'll plan on
re-implementing based on the new UserExpression class.
I just need to figure out how to add my user expression subclass to the
RowFilter programmatically via a QueryHandler implementation. [~beobal] Do you
have any pointers to code for a sample UserExpression and QueryHandler
registration code I could use as a starting point? Thank you for any tips.
> Complete support for CustomExpression
> -
>
> Key: CASSANDRA-11458
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11458
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
>Reporter: Henry Manasseh
>Priority: Minor
> Attachments: Custom-expression-Change.png, addCustomIndexExpression
> change.png
>
>
> This is a proposal to complete the CustomExpression support first introduced
> as part of https://issues.apache.org/jira/browse/CASSANDRA-10217.
> The current support for custom expressions is partial. There is no clean way
> to implement queries making use of the "exp('index', 'value)" syntax due to
> the fact CustomExpression is declared as final and there is no way to for
> developers to cleanly plug-in their own expressions.
> https://github.com/apache/cassandra/blob/6e69c75900f3640195130085ad69daa1659184eb/src/java/org/apache/cassandra/db/filter/RowFilter.java#L869
> The proposal is to make CustomExpression not final so that developers can
> extend and create their own subclass and provide their own isSatisfiedBy
> operation (which currently always returns true).
> Introducing a new custom expression would be done as follows:
> 1. Developer would create a subclass of CustomExpression and override
> isSatisfiedBy method with their logic (public boolean
> isSatisfiedBy(CFMetaData metadata, DecoratedKey partitionKey, Row row))
> 2. This class would be packaged in a jar and copied to the cassandra lib
> directory along with a secondary index class which overrides
> Index.customExpressionValueType
> 2. Create the custom index with an option which identifies the
> CustomExpression subclass (custom_expression_class).
> CREATE CUSTOM INDEX ON keyspace.my_table(my_indexed_column) USING
> 'org.custom.MyCustomIndex'
> WITH OPTIONS = { 'custom_expression_class': 'org.custom.MyCustomExpression' };
> I have prototyped the change and works as designed. In my case I do a type of
> "IN" query filter which will simplify my client logic significantly.
> The default behavior of using the CustomExpression class would be maintained
> if the developer does not provide a custom class in the create index options.
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