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https://issues.apache.org/jira/browse/BEAM-3157?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16361319#comment-16361319
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Anton Kedin edited comment on BEAM-3157 at 2/12/18 7:30 PM:
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Yes, this should be open until we have the code generation piece wired up with
user-friendly APIs. Specifics of the API would be defined by the schema-aware
PCollections design that [~reuvenlax] is working on.
I have put together a functional prototype of how RowType generation can be
wired up to SQL:
[https://github.com/apache/beam/pull/4649/commits/e12d54725ab092c260a7084f50012e4fe3d7e81b#diff-30ffc29d9ac0817e4e88622a81da8ec3R58]
:
* it is triggered by specifying the
InferredSqlRowCoder.ofSerializable(PersonPojo.class)) on the input PCollection;
* as an example it uses SerializableCoder for original PCollection elements
but it can be any other coder;
* InferredSqlRowCoder wraps the Row/RowType generation logic for the element
type, and this logic is then invoked by the SQL's QueryTransform;
I will be gathering feedback and waiting for further work on the schema-aware
PCollections before submitting this
was (Author: kedin):
Yes, this should be open until we have the code generation piece wired up with
user-friendly APIs. Specifics of the API would be defined by the schema-aware
PCollections design that [~reuvenlax] is working on.
I have put together a functional prototype of how RowType generation can be
wired up to SQL:
[https://github.com/apache/beam/pull/4649/commits/e12d54725ab092c260a7084f50012e4fe3d7e81b#diff-30ffc29d9ac0817e4e88622a81da8ec3R58]
I will be gathering feedback and waiting for further work on the schema-aware
PCollections before submitting this
> 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
> Assignee: Anton Kedin
> Priority: Major
> Fix For: 2.4.0
>
> Time Spent: 5h 20m
> Remaining Estimate: 0h
>
> 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:
> A simple filter:
> PCollection<MyPojo> col = BeamSql.query("SELECT * FROM .... WHERE
> ...").from(MyPojo.class);
> A projection:
> PCollection<MyNewPojo> newCol = BeamSql.query("SELECT id,
> name").from(MyPojo.class).as(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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