ODIn/spark-instrumented-optimizer
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
spark-instrumented-optimizer/docs/ss-migration-guide.md
Jungtaek Lim (HeartSaVioR) 8305b77796 [SPARK-28199][SPARK-28199][SS][FOLLOWUP] Mention the change of into the SS migration guide 
### What changes were proposed in this pull request?

SPARK-28199 (#24996) made the trigger related public API to be exposed only from static methods of Trigger class. This is backward incompatible change, so some users may experience compilation error after upgrading to Spark 3.0.0.

While we plan to mention the change into release note, it's good to mention the change to the migration guide doc as well, since the purpose of the doc is to collect the major changes/incompatibilities between versions and end users would refer the doc.

### Why are the changes needed?

SPARK-28199 is technically backward incompatible change and we should kindly guide the change.

### Does this PR introduce _any_ user-facing change?

Doc change.

### How was this patch tested?

N/A, as it's just a doc change.

Closes #28763 from HeartSaVioR/SPARK-28199-FOLLOWUP-doc.

Authored-by: Jungtaek Lim (HeartSaVioR) <kabhwan.opensource@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2020-06-09 04:52:48 +00:00

2.4 KiB
Raw Blame History

layout title displayTitle license
global Migration Guide: Structured Streaming Migration Guide: Structured Streaming 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.
  • Table of contents {:toc}

Note that this migration guide describes the items specific to Structured Streaming. Many items of SQL migration can be applied when migrating Structured Streaming to higher versions. Please refer Migration Guide: SQL, Datasets and DataFrame.

Upgrading from Structured Streaming 2.4 to 3.0

  • In Spark 3.0, Structured Streaming forces the source schema into nullable when file-based datasources such as text, json, csv, parquet and orc are used via spark.readStream(...). Previously, it respected the nullability in source schema; however, it caused issues tricky to debug with NPE. To restore the previous behavior, set spark.sql.streaming.fileSource.schema.forceNullable to false.

  • Spark 3.0 fixes the correctness issue on Stream-stream outer join, which changes the schema of state. (See SPARK-26154 for more details). If you start your query from checkpoint constructed from Spark 2.x which uses stream-stream outer join, Spark 3.0 fails the query. To recalculate outputs, discard the checkpoint and replay previous inputs.

  • In Spark 3.0, the deprecated class org.apache.spark.sql.streaming.ProcessingTime has been removed. Use org.apache.spark.sql.streaming.Trigger.ProcessingTime instead. Likewise, org.apache.spark.sql.execution.streaming.continuous.ContinuousTrigger has been removed in favor of Trigger.Continuous, and org.apache.spark.sql.execution.streaming.OneTimeTrigger has been hidden in favor of Trigger.Once.