Ismaël Mejía created BEAM-3157:
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Summary: BeamSql transform should support other PCollection types
Key: BEAM-3157
URL: https://issues.apache.org/jira/browse/BEAM-3157
Project: Beam
Issue Type: Improvement
Components: dsl-sql
Reporter: Ismaël Mejía
Currently the Beam SQL transform only supports input and output data
represented as a BeamRecord. This seems to me like an usability limitation
(even if we can do a ParDo to prepare objects before and after the transform).
I suppose this constraint comes from the fact that we need to map
name/type/value from an object field into Calcite so it is convenient to have a
specific data type (BeamRecord) for this. However we can accomplish the same by
using a PCollection of JavaBean (where we know the same information via the
field names/types/values) or by using Avro records where we also have the
Schema information. For the output PCollection we can map the object via a
Reference (e.g. a JavaBean to be filled with the names of an Avro object).
Note: I am assuming for the moment simple mappings since the SQL does not
support composite types for the moment.
A simple API idea would be something like this:
PCollection<MyPojo> col = ...
PCollection<>BeamSql.query("SELECT ...", MyNewPojo.class);
A first approach could be to just add the extra ParDos + transform DoFns
however I suppose that for memory use reasons maybe mapping directly into
Calcite would make sense.
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