org.apache.beam.sdk.extensions.sql

Class SqlTransform

java.lang.Object

org.apache.beam.sdk.transforms.PTransform<PInput,PCollection<Row>>

org.apache.beam.sdk.extensions.sql.SqlTransform

All Implemented Interfaces:

java.io.Serializable, HasDisplayData

@Experimental
public abstract class SqlTransform
extends PTransform<PInput,PCollection<Row>>

SqlTransform is the DSL interface of Beam SQL. It translates a SQL query as a PTransform, so developers can use standard SQL queries in a Beam pipeline.

Beam SQL DSL usage:

A typical pipeline with Beam SQL DSL is:

 PipelineOptions options = PipelineOptionsFactory.create();
 Pipeline p = Pipeline.create(options);

 //create table from TextIO;
 PCollection<Row> inputTableA = p.apply(TextIO.read().from("/my/input/patha")).apply(...);
 PCollection<Row> inputTableB = p.apply(TextIO.read().from("/my/input/pathb")).apply(...);

 //run a simple query, and register the output as a table in BeamSql;
 String sql1 = "select MY_FUNC(c1), c2 from PCOLLECTION";
 PCollection<Row> outputTableA = inputTableA.apply(
    SqlTransform
        .query(sql1)
        .registerUdf("MY_FUNC", MY_FUNC.class, "FUNC");

 //run a JOIN with one table from TextIO, and one table from another query
 PCollection<Row> outputTableB =
     PCollectionTuple
     .of(new TupleTag<>("TABLE_O_A"), outputTableA)
     .and(new TupleTag<>("TABLE_B"), inputTableB)
         .apply(SqlTransform.query("select * from TABLE_O_A JOIN TABLE_B where ..."));

 //output the final result with TextIO
 outputTableB.apply(...).apply(TextIO.write().to("/my/output/path"));

 p.run().waitUntilFinish();
 

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.beam.sdk.transforms.PTransform

name

Constructor Summary

Constructors

Constructor and Description
SqlTransform()

Method Summary

Modifier and Type	Method and Description
PCollection<Row>	expand(PInput input) Override this method to specify how this PTransform should be expanded on the given InputT.
static SqlTransform	query(java.lang.String queryString) Returns a SqlTransform representing an equivalent execution plan.
SqlTransform	registerUdaf(java.lang.String functionName, Combine.CombineFn combineFn) register a Combine.CombineFn as UDAF function used in this query.
SqlTransform	registerUdf(java.lang.String functionName, java.lang.Class<? extends BeamSqlUdf> clazz) register a UDF function used in this query.
SqlTransform	registerUdf(java.lang.String functionName, SerializableFunction sfn) Register SerializableFunction as a UDF function used in this query.

Methods inherited from class org.apache.beam.sdk.transforms.PTransform

getAdditionalInputs, getDefaultOutputCoder, getDefaultOutputCoder, getDefaultOutputCoder, getKindString, getName, populateDisplayData, toString, validate

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

SqlTransform

public SqlTransform()

Method Detail

expand

public PCollection<Row> expand(PInput input)

Description copied from class: PTransform

Override this method to specify how this PTransform should be expanded on the given InputT.

NOTE: This method should not be called directly. Instead apply the PTransform should be applied to the InputT using the apply method.

Composite transforms, which are defined in terms of other transforms, should return the output of one of the composed transforms. Non-composite transforms, which do not apply any transforms internally, should return a new unbound output and register evaluators (via backend-specific registration methods).

Specified by:

expand in class PTransform<PInput,PCollection<Row>>

query

public static SqlTransform query(java.lang.String queryString)

Returns a SqlTransform representing an equivalent execution plan.

The SqlTransform can be applied to a PCollection or PCollectionTuple representing all the input tables.

The PTransform outputs a PCollection of Row.

If the PTransform is applied to PCollection then it gets registered with name PCOLLECTION.

If the PTransform is applied to PCollectionTuple then TupleTag.getId() is used as the corresponding PCollections name.

• If the sql query only uses a subset of tables from the upstream PCollectionTuple, this is valid;
• If the sql query references a table not included in the upstream PCollectionTuple, an IllegalStateException is thrown during query validati on;
• Always, tables from the upstream PCollectionTuple are only valid in the scope of the current query call.

registerUdf

public SqlTransform registerUdf(java.lang.String functionName,
                                java.lang.Class<? extends BeamSqlUdf> clazz)

register a UDF function used in this query.

Refer to BeamSqlUdf for more about how to implement a UDF in BeamSql.

registerUdf

public SqlTransform registerUdf(java.lang.String functionName,
                                SerializableFunction sfn)

Register SerializableFunction as a UDF function used in this query. Note, SerializableFunction must have a constructor without arguments.

registerUdaf

public SqlTransform registerUdaf(java.lang.String functionName,
                                 Combine.CombineFn combineFn)

register a Combine.CombineFn as UDAF function used in this query.