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https://issues.apache.org/jira/browse/CASSANDRA-7395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Robert Stupp updated CASSANDRA-7395:
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Attachment: 7395.diff
Attached is some code for UDF functions.
Very simple - dirty code...
Just intended as input for the concept discussion
Concept for this POC hack was:
* Functions are grouped into bundles (which are jar files)
* Bundles are replicated in separate KS
* new {{UDFRegistry}} hooked into {{Functions}}
* bundles are managed by user tool "udfloader"
Idea:
* Use some namespace handling for functions - e.g. something like {{SELECT
Math.sin(column) FROM ...}} would require the Math bundle
* Other people can write a more sophisticated bundle - e.g. a StrictMath bundle
Short instructions for this patch:
1. Build C*
1. Execute {{ant}} in directory {{udf-demo}}
1. Start C*
1. Load UDF bundle using {{tools/bin/udfloader -b demo -f
udf-demo/build/udf-demo.jar}}
1. Exec cqlsh: {noformat}
cqlsh> create keyspace foo WITH REPLICATION = { 'class' : 'SimpleStrategy',
'replication_factor' : 2 };
cqlsh> create table foo.demo (id int primary key, num double);
cqlsh> insert into foo.demo values (1,1);
cqlsh> select id, num, Sin(num) from foo.demo;
id | num | Sin_num
----+-----+---------
1 | 1 | 0.84147
(1 rows)
{noformat}
> Support for pure user-defined functions (UDF)
> ---------------------------------------------
>
> Key: CASSANDRA-7395
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7395
> Project: Cassandra
> Issue Type: New Feature
> Components: API, Core
> Reporter: Jonathan Ellis
> Fix For: 3.0
>
> Attachments: 7395.diff
>
>
> We have some tickets for various aspects of UDF (CASSANDRA-4914,
> CASSANDRA-5970, CASSANDRA-4998) but they all suffer from various degrees of
> ocean-boiling.
> Let's start with something simple: allowing pure user-defined functions in
> the SELECT clause of a CQL query. That's it.
> By "pure" I mean, must depend only on the input parameters. No side effects.
> No exposure to C* internals. Column values in, result out.
> http://en.wikipedia.org/wiki/Pure_function
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