[GitHub] [airflow] potiuk commented on a change in pull request #8877: Add S3ToRedshift example dag and system test

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

potiuk commented on a change in pull request #8877:
URL: https://github.com/apache/airflow/pull/8877#discussion_r438204839



##########
File path: airflow/providers/amazon/aws/example_dags/example_s3_to_redshift.py
##########
@@ -0,0 +1,53 @@
+# 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 is an example dag for using `S3ToRedshiftTransfer` to copy a S3 key into a Redshift table.
+"""
+
+from os import getenv
+
+from airflow import DAG
+from airflow.providers.amazon.aws.operators.s3_to_redshift import S3ToRedshiftTransfer
+from airflow.utils.dates import days_ago
+
+# [START howto_operator_s3_to_redshift_env_variables]
+S3_BUCKET = getenv("S3_BUCKET", "bucket")
+S3_KEY = getenv("S3_KEY", "key")

Review comment:
       I think this is fine and when we automate it, we should define files where we define ENV variables.
   
   Using  Airflow Variables in example DAGs is a very bad idea. People use it as  - well - examples - and using airflow Variables in DAGs in this way is very bad from Database load point of view. Until we avoid parsing the DAGs by all entities frequently we should not use variables in this way (we even have best practice about it)  - basically every time the DAG is parsed, DB communication occurs and the extra connection is made - that is quite bad for scalability and not obvious at all, so if people take that literally as examples (which they did in the past) they will implement bad practices.




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