[GitHub] [flink] joemoe commented on a diff in pull request #19584: release notes for the 1.15 release

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

joemoe commented on code in PR #19584:
URL: https://github.com/apache/flink/pull/19584#discussion_r858635119


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docs/content/release-notes/flink-1.15.md:
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+---
+title: "Release Notes - Flink 1.15"
+---
+<!--
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+KIND, either express or implied.  See the License for the
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+
+# Release notes - Flink 1.15
+
+These release notes discuss important aspects, such as configuration, behavior, 
+or dependencies, that changed between Flink 1.14 and Flink 1.15. Please read these 
+notes carefully if you are planning to upgrade your Flink version to 1.15.
+
+## Summary of changed dependency names
+
+There are three changes in Flink 1.15 that require updating dependency names when 
+upgrading from earlier versions:
+
+* The newly introduced module `flink-table-planner-loader` (FLINK-25128) could 
+  replace the legacy `flink-table-planner_2.12`. As a consequence, `flink-table-uber` 
+  has been split into `flink-table-api-java-uber`, `flink-table-planner(-loader), 
+  and `table-runtime`. Besides, the artifactId of `flink-sql-client` has no Scala 
+  suffix (_2.11 / _2.12) anymore, and Scala users need to explicitly add a 
+  dependency to `flink-table-api-scala` or `flink-table-api-scala-bridge`.
+* Due to the efforts of removing Scala dependency from `flink-table-runtime` 
+  (FLINK-25114), the artifactId of `flink-table-runtime` has no Scala version 
+  suffix (\_2.11 / \_2.12) any more.
+* The FileSystem connector is no longer a part of the `flink-table-uber` module 
+  and changed to an optional dedicated `flink-connector-files` module 
+  (FLINK-24687). Besides, the artifactId of `flink-orc`, `flink-orc-nohive`, 
+  `flink-parquet` has no Scala suffix (\_2.11 / \_2.12) anymore.
+
+## JDK Upgrade
+
+The support of Java 8 is now deprecated and will be removed in a future release 
+([FLINK-25247](https://issues.apache.org/jira/browse/FLINK-25247)). We recommend 
+all users to migrate to Java 11.
+
+The default Java version in the Flink docker images is now Java 11 
+([FLINK-25251](https://issues.apache.org/jira/browse/FLINK-25251)). 
+There are images built with Java 8, tagged with “java8”. 
+
+## DataStream API
+
+### [TypeSerializer version mismatch during eagerly restore (FLINK-24858)](https://issues.apache.org/jira/browse/FLINK-24858)
+
+This ticket resolves an issue that during state migration between Flink versions
+the wrong serializer might have been picked.
+
+When upgrading from Flink 1.13.x please immediately choose 1.14.3 or higher and 
+skip 1.14.0, 1.14.1, 1.14.2 because all are affected and it might prevent your 
+job from starting.
+
+## Table API & SQL
+
+### [Make the legacy behavior disabled by default (FLINK-26551)](https://issues.apache.org/jira/browse/FLINK-26551)
+
+The legacy casting behavior has been disabled by default. This might have 
+implications on corner cases (string parsing, numeric overflows, to string 
+representation, varchar/binary precisions). Set 
+`table.exec.legacy-cast-behaviour=ENABLED` to restore the old behavior.
+
+### [Enforce CHAR/VARCHAR precision when outputting to a Sink (FLINK-24753)](https://issues.apache.org/jira/browse/FLINK-24753)
+
+`CHAR`/`VARCHAR` lengths are enforced (trimmed/padded) by default now before entering
+the table sink.
+
+### [Support the new type inference in Scala Table API table functions (FLINK-26518)](https://issues.apache.org/jira/browse/FLINK-26518)
+
+Table functions that are called using Scala implicit conversions have been updated 
+to use the new type system and new type inference. Users are requested to update 
+their UDFs or use the deprecated `TableEnvironment.registerFunction` to restore 
+the old behavior temporarily by calling the function via name.
+
+### [Propagate executor config to TableConfig (FLINK-26421)](https://issues.apache.org/jira/browse/FLINK-26421)
+
+`flink-conf.yaml` and other configurations from outer layers (e.g. CLI) are now 
+propagated into `TableConfig`. Even though configuration set directly in `TableConfig` 
+has still precedence, this change can have side effects if table configuration 
+was accidentally set in other layers.
+
+### [Remove pre FLIP-84 methods (FLINK-26090)](https://issues.apache.org/jira/browse/FLINK-26090)
+
+The previously deprecated methods `TableEnvironment.execute`, `Table.insertInto`,
+`TableEnvironment.fromTableSource`, `TableEnvironment.sqlUpdate`, and 
+`TableEnvironment.explain` have been removed. Please use the provided 
+alternatives introduced in 
+[FLIP-84](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=134745878).
+
+### [Fix parser generator warnings (FLINK-26053)](https://issues.apache.org/jira/browse/FLINK-26053)
+
+`STATEMENT` is a reserved keyword now. Use backticks to escape tables, fields and 
+other references.
+
+### [Expose uid generator for DataStream/Transformation providers (FLINK-25990)](https://issues.apache.org/jira/browse/FLINK-25990)
+
+`DataStreamScanProvider` and `DataStreamSinkProvider` for table connectors received 
+an additional method that might break implementations that used lambdas before. 
+We recommend static classes as a replacement and future robustness.
+
+### [Add new STATEMENT SET syntax (FLINK-25392)](https://issues.apache.org/jira/browse/FLINK-25392)
+
+It is recommended to update statement sets to the new SQL syntax: 
+
+```SQL
+EXECUTE STATEMENT SET BEGIN ... END;
+EXPLAIN STATEMENT SET BEGIN ... END;
+```
+
+### [Check & possible fix decimal precision and scale for all Aggregate functions (FLINK-24809)](https://issues.apache.org/jira/browse/FLINK-functions)
+
+This changes the result of a decimal `SUM()` with retraction and `AVG()` between
+1.14.0 and 1.14.1. It restores the behavior of 1.13 to be consistent with Hive/Spark.
+
+### [Clarify semantics of DecodingFormat and its data type (FLINK-24776)](https://issues.apache.org/jira/browse/FLINK-24776)
+
+The `DecodingFormat` interface was used for both projectable and non-projectable
+formats which led to inconsistent implementations. The `FileSystemTableSource` 
+has been updated to distinguish between those two interfaces now. Users that 
+implement custom formats for `FileSystemTableSource` might need to verify the 
+implementation and make sure to implement `ProjectableDecodingFormat` if necessary.
+
+### [Update user document for batch window tvf (FLINK-24760)](https://issues.apache.org/jira/browse/FLINK-24760)
+
+All window table-valued functions can now also be used in batch mode.
+
+### [Add user document for Window Deduplication (FLINK-24656)](https://issues.apache.org/jira/browse/FLINK-24656)
+
+Flink SQL now also supports Window Deduplication as a new window table-valued function.
+`WindowDeduplication` is a deduplication operator which removes rows that duplicate
+over a set of columns, keeping only the first one or the last one for each window
+and other partitioned keys.
+
+### [Push down partitions before filters (FLINK-24717)](https://issues.apache.org/jira/browse/FLINK-24717)
+
+This might have an impact on existing table source implementations as push down 
+filters might not contain partition predicates anymore. However, the connector 
+implementation for table sources that implement both partition and filter push 
+down became easier with this change.
+
+### [Flink SQL `SUM()` causes a precision error (FLINK-24691)](https://issues.apache.org/jira/browse/FLINK-24691)
+
+This changes the result of a decimal `SUM()` between 1.14.0 and 1.14.1. It restores 
+the behavior of 1.13 to be consistent with Hive/Spark.
+
+### [Use the new casting rules in TableResult#print (FLINK-24685)](https://issues.apache.org/jira/browse/FLINK-24685)
+
+The string representation of `BOOLEAN` columns from DDL results 
+(`true/false -> TRUE/FALSE`), and row columns in DQL results 
+(`+I[...] -> (...)`) has changed for printing.
+
+### [Sinks built with the unified sink framework do not receive timestamps when used in Table API (FLINK-24608)](https://issues.apache.org/jira/browse/FLINK-Table)
+
+This adds an additional operator to the topology if the new sink interfaces are used 
+(e.g. for Kafka). It could cause issues in 1.14.1 when restoring from a 1.14 savepoint. 
+A workaround is to cast the time attribute to a regular timestamp in the SQL statement
+closely before the sink.
+
+### [SQL functions should return `STRING` instead of `VARCHAR(2000)` (FLINK-24586)](https://issues.apache.org/jira/browse/FLINK-24586)
+
+Functions that returned `VARCHAR(2000)` in 1.14, return `VARCHAR` with maximum 
+length now. In particular this includes:
+
+```SQL
+SON_VALUE
+CHR
+REVERSE
+SPLIT_INDEX
+REGEXP_EXTRACT
+PARSE_URL
+FROM_UNIXTIME
+DECODE
+DATE_FORMAT
+CONVERT_TZ
+```
+
+## Connectors
+
+### [(Introducing GCS FileSystem Support and) Update GCS documentation (FLINK-25577)](https://issues.apache.org/jira/browse/FLINK-25577)
+
+The `flink-gs-fs-hadoop` FileSystem plugin for Google Cloud Storage (GCS) has been
+introduced. This allows Flink to read data from and write data to GCS via paths with 
+the `gs://` scheme, and it provides similar functionality for GCS as, for example, 
+the `flink-s3-fs-hadoop` provides for Amazon S3.
+
+In particular, this plugin supports the `RecoverableWriter` interface, which 
+allows it to be used with file sinks.
+
+Under the hood, the `flink-gs-fs-hadoop` uses Google's `gcs-connector` Hadoop 
+library for basic read/write operations, and it uses Google's `google-cloud-storage` 
+library to implement `RecoverableWriter` functionality.
+
+### [Remove MapR filesystem (FLINK-25553)](https://issues.apache.org/jira/browse/FLINK-25553)
+
+Support for the MapR FileSystem has been dropped.
+
+### [Make flink-connector-base dependency usage consistent across all connectors (FLINK-25927)](https://issues.apache.org/jira/browse/FLINK-25927)
+
+`flink-connector-base` was previously inconsistently used in connectors (directly 
+shaded in some and transitively pulled in via `flink-connector-files` which was 
+itself shaded in the table uber jar). 
+[FLINK-24687](https://issues.apache.org/jira/browse/FLINK-24687) moved 
+`flink-connector-files` 
+out of the `flink-table` uber jar. In order to address this, Flink 1.15 implements
+a combined approach for both making usage of `flink-connector-base` consistent 
+and ensuring a smooth transition for both Flink users and for external connector
+developers:
+
+1. all internal Flink connectors that depend on `flink-connector-base` now shade

Review Comment:
   would be good if you could elaborate @AHeise @afedulov.



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