[GitHub] [airflow] dbarrundiag commented on a diff in pull request #22692: Add support for Delta Sharing protocol

[GitBox <gi...@apache.org>]

dbarrundiag commented on code in PR #22692:
URL: https://github.com/apache/airflow/pull/22692#discussion_r857231218


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airflow/providers/delta/sharing/operators/delta_sharing.py:
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@@ -0,0 +1,227 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you 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.
+#
+"""This module contains Delta Sharing operators."""
+import json
+import os.path
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from typing import TYPE_CHECKING, Any, Dict, List, Optional, Sequence
+from urllib.parse import urlparse
+
+import requests
+
+from airflow import AirflowException
+from airflow.models import BaseOperator
+from airflow.providers.delta.sharing.hooks.delta_sharing import DeltaSharingHook
+
+if TYPE_CHECKING:
+    from airflow.utils.context import Context
+
+
+class DeltaSharingLocalDownloadOperator(BaseOperator):
+    """
+    Operator to download data from a Delta Sharing table to a local disk.
+
+    :param share: name of the share in which check will be performed.
+        This field will be templated.
+    :param schema: name of the schema (database) in which check will be performed.
+        This field will be templated.
+    :param table: name of the table to check.
+        This field will be templated.
+    :param location: name of directory where downloaded data will be stored.
+        This field will be templated.
+    :param limit: optional limit on the number of records to return.
+    :param predicates: optional list of strings that will be ANDed to build a filter expression.
+        This field will be templated.
+    :param save_partitioned: if True, data will be saved by partitions. if False, all data files will be
+       saved into a top-level directory.
+    :param save_metadata:  if True, metadata will be shared into a ``_metadata/<version>.json`` file
+    :param save_stats: if True, per-file statistics will be saved into a ``_stats/<data_file_name>.json``
+    :param overwrite_existing: Overwrite existing files.  False by default. If file with the same name exists
+        and has the same size as returned in file metadata, then it won't be re-downloaded.
+    :param num_parallel_downloads: number of parallel downloads. Default is 5.
+    :param delta_sharing_conn_id: Reference to the
+        :ref:`Delta Sharing connection <howto/connection:delta_sharing>`.
+        By default and in the common case this will be ``delta_sharing_default``. To use
+        token based authentication, provide the bearer token in the password field for the
+        connection and put the base URL in the ``host`` field.
+    :param profile_file: Optional path or HTTP(S) URL to a Delta Sharing profile file.
+        If this parameter is specified, the ``delta_sharing_conn_id`` isn't used.
+    :param timeout_seconds: The timeout for this run. By default a value of 0 is used
+        which means to have no timeout.
+    :param retry_limit: Amount of times retry if the Delta Sharing backend is
+        unreachable. Its value must be greater than or equal to 1.
+    :param retry_delay: Number of seconds for initial wait between retries (it
+            might be a floating point number).
+    :param retry_args: An optional dictionary with arguments passed to ``tenacity.Retrying`` class.
+    """
+
+    template_fields: Sequence[str] = (
+        'share',
+        'schema',
+        'table',
+        'predicates',
+        'location',
+    )
+
+    # Used in airflow.models.BaseOperator
+    # Delta Sharing brand color (blue) under white text
+    ui_color = '#1CB1C2'
+    ui_fgcolor = '#fff'
+
+    def __init__(
+        self,
+        *,
+        share: str,
+        schema: str,
+        table: str,
+        location: str,
+        limit: Optional[int] = None,
+        predicates: Optional[List[str]] = None,
+        save_partitioned: bool = True,
+        save_metadata: bool = True,
+        save_stats: bool = True,
+        overwrite_existing: bool = False,
+        num_parallel_downloads: int = 5,
+        delta_sharing_conn_id: str = 'delta_sharing_default',
+        profile_file: Optional[str] = None,
+        timeout_seconds: int = 180,
+        retry_limit: int = 3,
+        retry_delay: float = 2.0,
+        retry_args: Optional[Dict[Any, Any]] = None,
+        **kwargs,
+    ) -> None:
+        """Creates a new ``DeltaSharingDownloadToLocalOperator``."""
+        super().__init__(**kwargs)
+        self.share = share
+        self.schema = schema
+        self.table = table
+        self.location = location
+        if limit is not None and limit < 0:
+            raise ValueError(f"limit should be greater or equal to 0, got {limit}")
+        self.limit = limit
+        self.predicates = predicates
+        self.save_partitioned = save_partitioned
+        self.save_stats = save_stats
+        self.save_metadata = save_metadata
+        self.overwrite_existing = overwrite_existing
+        if num_parallel_downloads < 1:
+            raise ValueError(
+                "num_parallel_downloads should be greater or equal to 1," f" got {num_parallel_downloads}"
+            )
+        self.num_parallel_downloads = num_parallel_downloads
+
+        self.hook = DeltaSharingHook(
+            delta_sharing_conn_id=delta_sharing_conn_id,
+            retry_args=retry_args,
+            retry_delay=retry_delay,
+            retry_limit=retry_limit,
+            timeout_seconds=timeout_seconds,
+            profile_file=profile_file,
+        )
+
+    def _get_output_file_path(self, metadata: Dict[str, Any], file: Dict[str, Any]) -> str:
+        chunks = urlparse(file['url'])
+        file_name = chunks.path.split('/')[-1]
+        file_parts = [self.location]
+        # add partition parts if table is partitioned
+        partition_values = file.get('partitionValues', {})
+        if self.save_partitioned and len(partition_values) > 0:
+            partitions = metadata.get('partitionColumns', [])
+            for part in partitions:
+                part_value = partition_values.get(part)
+                if part_value is None:
+                    self.log.warning(f"There is no value for partition '{part}'")
+                    part_value = "__null__"
+                file_parts.append(f"{part}={part_value}")
+
+        os.makedirs(os.path.join(*file_parts), exist_ok=True)
+        file_parts.append(file_name)
+        return os.path.join(*file_parts)
+
+    def _download_one(self, metadata: Dict[str, Any], file: Dict[str, Any]):
+        dest_file_path = self._get_output_file_path(metadata, file)
+        file_size = file['size']
+        if os.path.exists(dest_file_path):
+            stat = os.stat(dest_file_path)
+            if file_size == stat.st_size and not self.overwrite_existing:

Review Comment:
   Might be safer if we do some sort of MD5 checksum check here and not just the size of the file?



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