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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""BigQuery reading support for TensorFlow."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from tensorflow.contrib.cloud.python.ops import gen_bigquery_reader_ops
from tensorflow.python.framework import ops
from tensorflow.python.ops import io_ops
class BigQueryReader(io_ops.ReaderBase):
"""A Reader that outputs keys and tf.Example values from a BigQuery table.
Example use:
```python
# Assume a BigQuery has the following schema,
# name STRING,
# age INT,
# state STRING
# Create the parse_examples list of features.
features = dict(
name=tf.FixedLenFeature([1], tf.string),
age=tf.FixedLenFeature([1], tf.int32),
state=tf.FixedLenFeature([1], dtype=tf.string, default_value="UNK"))
# Create a Reader.
reader = bigquery_reader_ops.BigQueryReader(project_id=PROJECT,
dataset_id=DATASET,
table_id=TABLE,
timestamp_millis=TIME,
num_partitions=NUM_PARTITIONS,
features=features)
# Populate a queue with the BigQuery Table partitions.
queue = tf.training.string_input_producer(reader.partitions())
# Read and parse examples.
row_id, examples_serialized = reader.read(queue)
examples = tf.parse_example(examples_serialized, features=features)
# Process the Tensors examples["name"], examples["age"], etc...
```
Note that to create a reader a snapshot timestamp is necessary. This
will enable the reader to look at a consistent snapshot of the table.
For more information, see 'Table Decorators' in BigQuery docs.
See ReaderBase for supported methods.
"""
def __init__(self,
project_id,
dataset_id,
table_id,
timestamp_millis,
num_partitions,
features=None,
columns=None,
test_end_point=None,
name=None):
"""Creates a BigQueryReader.
Args:
project_id: GCP project ID.
dataset_id: BigQuery dataset ID.
table_id: BigQuery table ID.
timestamp_millis: timestamp to snapshot the table in milliseconds since
the epoch. Relative (negative or zero) snapshot times are not allowed.
For more details, see 'Table Decorators' in BigQuery docs.
num_partitions: Number of non-overlapping partitions to read from.
features: parse_example compatible dict from keys to `VarLenFeature` and
`FixedLenFeature` objects. Keys are read as columns from the db.
columns: list of columns to read, can be set iff features is None.
test_end_point: Used only for testing purposes (optional).
name: a name for the operation (optional).
Raises:
TypeError: - If features is neither None nor a dict or
- If columns is neither None nor a list or
- If both features and columns are None or set.
"""
if (features is None) == (columns is None):
raise TypeError("exactly one of features and columns must be set.")
if features is not None:
if not isinstance(features, dict):
raise TypeError("features must be a dict.")
self._columns = list(features.keys())
elif columns is not None:
if not isinstance(columns, list):
raise TypeError("columns must be a list.")
self._columns = columns
self._project_id = project_id
self._dataset_id = dataset_id
self._table_id = table_id
self._timestamp_millis = timestamp_millis
self._num_partitions = num_partitions
self._test_end_point = test_end_point
reader = gen_bigquery_reader_ops.big_query_reader(
name=name,
project_id=self._project_id,
dataset_id=self._dataset_id,
table_id=self._table_id,
timestamp_millis=self._timestamp_millis,
columns=self._columns,
test_end_point=self._test_end_point)
super(BigQueryReader, self).__init__(reader)
def partitions(self, name=None):
"""Returns serialized BigQueryTablePartition messages.
These messages represent a non-overlapping division of a table for a
bulk read.
Args:
name: a name for the operation (optional).
Returns:
`1-D` string `Tensor` of serialized `BigQueryTablePartition` messages.
"""
return gen_bigquery_reader_ops.generate_big_query_reader_partitions(
name=name,
project_id=self._project_id,
dataset_id=self._dataset_id,
table_id=self._table_id,
timestamp_millis=self._timestamp_millis,
num_partitions=self._num_partitions,
test_end_point=self._test_end_point,
columns=self._columns)
ops.NotDifferentiable("BigQueryReader")
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