Pradeep A Dalvi created APEXMALHAR-2015:
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Summary: Projection Operator
Key: APEXMALHAR-2015
URL: https://issues.apache.org/jira/browse/APEXMALHAR-2015
Project: Apache Apex Malhar
Issue Type: New Feature
Reporter: Pradeep A Dalvi
Projection Operator will allow apex users to project (select/drop) certain
fields from the incoming tuples. This operation might be done unconditionally
or based on certain condition.
Use case:
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Not all fields of tuples are of interest for the downstream operators. In such
cases, one may want project selective fields to downstream. Also one may want
to drop few fields, instead of selecting many.
In certain scenarios, one may want to project certain fields based on given
condition or expression.
Functionality:
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1. Projection operator shall receive POJO as input tuple and emit 2 POJOs on
separate output ports i.e. selected and dropped. Selected output port shall
emit POJO with selected fields and dropped output shall emit POJO of dropped
fields.
2. Operator needs select or drop fields as input params. This shall be
specified using comma separated list of fields.
3. Operator shall emit POJO only on connected output ports. In another words,
if dropped output port is not connected, it shall not even try to generate
POJOs with dropped fields.
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