Source code for apache_beam.transforms.sql

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"""Package for SqlTransform and related classes."""

# pytype: skip-file

import typing

from apache_beam.transforms.external import BeamJarExpansionService
from apache_beam.transforms.external import ExternalTransform
from apache_beam.transforms.external import NamedTupleBasedPayloadBuilder

__all__ = ['SqlTransform']

SqlTransformSchema = typing.NamedTuple(
    'SqlTransformSchema', [('query', str), ('dialect', typing.Optional[str])])

[docs]class SqlTransform(ExternalTransform): """A transform that can translate a SQL query into PTransforms. Input PCollections must have a schema. Currently, there are two ways to define a schema for a PCollection: 1) Register a `typing.NamedTuple` type to use RowCoder, and specify it as the output type. For example:: Purchase = typing.NamedTuple('Purchase', [('item_name', unicode), ('price', float)]) coders.registry.register_coder(Purchase, coders.RowCoder) with Pipeline() as p: purchases = (p | | beam.Map(..).with_output_types(Purchase)) 2) Produce `beam.Row` instances. Note this option will fail if Beam is unable to infer data types for any of the fields. For example:: with Pipeline() as p: purchases = (p | | beam.Map(lambda x: beam.Row(item_name=unicode(..), price=float(..)))) Similarly, the output of SqlTransform is a PCollection with a schema. The columns produced by the query can be accessed as attributes. For example:: purchases | SqlTransform(\"\"\" SELECT item_name, COUNT(*) AS `count` FROM PCOLLECTION GROUP BY item_name\"\"\") | beam.Map(lambda row: "We've sold %d %ss!" % (row.count, row.item_name)) Additional examples can be found in `apache_beam.examples.wordcount_xlang_sql`, `apache_beam.examples.sql_taxi`, and `apache_beam.transforms.sql_test`. For more details about Beam SQL in general see the `Java transform <>`_, and the `documentation <>`_. """ URN = 'beam:external:java:sql:v1' def __init__(self, query, dialect=None, expansion_service=None): """ Creates a SqlTransform which will be expanded to Java's SqlTransform. (See class docs). :param query: The SQL query. :param dialect: (optional) The dialect, e.g. use 'zetasql' for ZetaSQL. :param expansion_service: (optional) The URL of the expansion service to use """ expansion_service = expansion_service or BeamJarExpansionService( ':sdks:java:extensions:sql:expansion-service:shadowJar') super().__init__( self.URN, NamedTupleBasedPayloadBuilder( SqlTransformSchema(query=query, dialect=dialect)), expansion_service=expansion_service)