add 2.2 release notes for zh
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@@ -0,0 +1,243 @@ +--- +title: "Release Notes - Flink 2.2" +--- + +<!-- +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. +--> + +# Release notes - Flink 2.2 + +These release notes discuss important aspects, such as configuration, behavior or dependencies, +that changed between Flink 2.1 and Flink 2.2. Please read these notes carefully if you are +planning to upgrade your Flink version to 2.2. + +### Table SQL / API + +#### Support VECTOR_SEARCH in Flink SQL + +##### [FLINK-38422](https://issues.apache.org/jira/browse/FLINK-38422) + +Apache Flink has supported leveraging LLM capabilities through the `ML_PREDICT` function in Flink SQL +since version 2.1, enabling users to perform semantic analysis in a simple and efficient way. This +integration has been technically validated in scenarios such as log classification and real-time +question-answering systems. However, the current architecture allows Flink to only use embedding +models to convert unstructured data (e.g., text, images) into high-dimensional vector features, +which are then persisted to downstream storage systems. It lacks real-time online querying and +similarity analysis capabilities for vector spaces. The VECTOR_SEARCH function is provided in Flink +2.2 to enable users to perform streaming vector similarity searches and real-time context retrieval +directly within Flink. + +See more details about the capabilities and usages of +Flink's [Vector Search](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/sql/reference/queries/vector-search/). + +#### Realtime AI Function + +##### [FLINK-38104](https://issues.apache.org/jira/browse/FLINK-38104) + +Apache Flink has supported leveraging LLM capabilities through the `ML_PREDICT` function in Flink SQL +since version 2.1. In Flink 2.2, the Table API also supports model inference operations that allow +you to integrate machine learning models directly into your data processing pipelines. + +See more details about the capabilities and usages of +Flink's [Model Inference](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/dev/table/tableapi/#model-inference). + +#### Materialized Table + +##### [FLINK-38532](https://issues.apache.org/jira/browse/FLINK-38532), [FLINK-38311](https://issues.apache.org/jira/browse/FLINK-38311) + +By specifying data freshness and query when creating [Materialized Table](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/sql/materialized-table/overview/), +the engine automatically derives the schema for the materialized table and creates corresponding +data refresh pipeline to achieve the specified freshness. + +From Flink 2.2, the FRESHNESS clause is not a mandatory part of the CREATE MATERIALIZED TABLE and +CREATE OR ALTER MATERIALIZED TABLE DDL statements. Flink 2.2 introduces a new MaterializedTableEnricher +interface. This provides a formal extension point for customizable default logic, allowing advanced +users and vendors to implement "smart" default behaviors (e.g., inferring freshness from upstream tables). + +Besides this, users can use `DISTRIBUTED BY` or`DISTRIBUTED INTO` to support bucketing concept +for Materialized tables. Users can use `SHOW MATERIALIZED TABLES` to show all Materialized tables. + +#### SinkUpsertMaterializer V2 + +##### [FLINK-38459](https://issues.apache.org/jira/browse/FLINK-38459) + +SinkUpsertMaterializer is an operator in Flink that reconciles out of order changelog events before +sending them to an upsert sink. Performance of this operator degrades exponentially in some cases. +Flink 2.2 introduces a new implementation that is optimized for such cases. + +#### Delta Join + +##### [FLINK-38495](https://issues.apache.org/jira/browse/FLINK-38495), [FLINK-38511](https://issues.apache.org/jira/browse/FLINK-38511), [FLINK-38556](https://issues.apache.org/jira/browse/FLINK-38556) + +In 2.1, Apache Flink has introduced a new delta join operator to mitigate the challenges caused by +big state in regular joins. It replaces the large state maintained by regular joins with a +bidirectional lookup-based join that directly reuses data from the source tables. + +Flink 2.2 enhances support for converting more SQL patterns into delta joins. Delta joins now +support consuming CDC sources without DELETE operations, and allow projection and filter operations +after the source. Additionally, delta joins include support for caching, which helps reduce requests +to external storage. + +See more details about the capabilities and usages of Flink's +[Delta Joins](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/dev/table/tuning/#delta-joins). + +#### SQL Types + +##### [FLINK-20539](https://issues.apache.org/jira/browse/FLINK-20539), [FLINK-38181](https://issues.apache.org/jira/browse/FLINK-38181) + +Before Flink 2.2, row types defined in SQL e.g. `SELECT CAST(f AS ROW<i NOT NULL>)` did ignore +the `NOT NULL` constraint. This was more aligned with the SQL standard but caused many type +inconsistencies and cryptic error message when working on nested data. For example, it prevented +using rows in computed columns or join keys. The new behavior takes the nullability into consideration. +The config option `table.legacy-nested-row-nullability` allows to restore the old behavior if required, +but it is recommended to update existing queries that ignored constraints before. + +Casting to TIME type now considers the correct precision (0-3). Casting incorrect strings to time +(e.g. where the hour component is higher than 24) leads to a runtime exception now. Casting between +BINARY and VARBINARY should now correctly consider the target length. + +#### Use UniqueKeys instead of Upsertkeys for state management + +##### [FLINK-38209](https://issues.apache.org/jira/browse/FLINK-38209) + +This is considerable optimization and an breaking change for the StreamingMultiJoinOperator. +As noted in the release notes, the operator was launched in an experimental state for Flink 2.1 +since we're working on relevant optimizations that could be breaking changes. + +### Runtime + +#### Balanced Tasks Scheduling + +##### [FLINK-31757](https://issues.apache.org/jira/browse/FLINK-31757) + +Introducing a balanced tasks scheduling strategy to achieve task load balancing for TMs and reducing +job bottlenecks. + +See more details about the capabilities and usages of +Flink's [Balanced Tasks Scheduling](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/deployment/tasks-scheduling/balanced_tasks_scheduling/). + +#### Enhanced Job History Retention Policies for HistoryServer + +##### [FLINK-38229](https://issues.apache.org/jira/browse/FLINK-38229) + +Before Flink 2.2, HistoryServer supports only a quantity-based job archive retention policy and +is insufficient for scenarios, requiring time-based retention or combined rules. Users can use +the new configuration `historyserver.archive.retained-ttl` combining with `historyserver.archive.retained-jobs` +to fulfill more scenario requirements. + +#### Metrics + +##### [FLINK-38158](https://issues.apache.org/jira/browse/FLINK-38158), [FLINK-38353](https://issues.apache.org/jira/browse/FLINK-38353) + +Since 2.2.0 users can now assign custom metric variables for each operator/transformation used in the +Job. Those variables are later converted to tags/labels by the metric reporters, allowing users to +tab/label specific operator's metrics. For example, you can use this to name and differentiate sources. + +Users can now control the level of details of checkpoint spans via [traces.checkpoint.span-detail-level](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/deployment/config/#traces-checkpoint-span-detail-level). +Highest levels report tree of spans for each task and subtask. Reported custom spans can now contain +children spans. See more details in [Traces](https://nightlies.apache.org/flink/flink-docs-release-2.2/docs/ops/traces/). + +#### Introduce Event Reporting + +##### [FLINK-37426](https://issues.apache.org/jira/browse/FLINK-37426) + +Since 2.1.0 users are able to report custom events using the EventReporters. Since 2.2.0 Flink reports +some built-in/system events. + +### Connectors + +#### Introduce RateLimiter for Source + +##### [FLINK-38497](https://issues.apache.org/jira/browse/FLINK-38497) + +Flink jobs frequently exchange data with external systems, which consumes their network bandwidth +and CPU. When these resources are scarce, pulling data too aggressively can disrupt other workloads. +In Flink 2.2, we introduce a RateLimiter interface to provide request rate limiting for Scan Sources +and connector developers can integrate with rate limiting frameworks to implement their own read +restriction strategies. This feature is currently only available in the DataStream API. + +#### Balanced splits assignment + +##### [FLINK-38564](https://issues.apache.org/jira/browse/FLINK-38564) + +SplitEnumerator is responsible for assigning splits, but it lacks visibility into the actual runtime +status or distribution of these splits. This makes it impossible for SplitEnumerator to guarantee +that the sharding is evenly distributed, and data skew is very likely to occur. From Flink 2.2, +SplitEnumerator has the information of the splits distribution and provides the ability to evenly +assign splits at runtime. + +### Python + +#### Support async function in Python DataStream API + +##### [FLINK-38190](https://issues.apache.org/jira/browse/FLINK-38190) + +In Flink 2.2, we have added support of async function in Python DataStream API. This enables Python +users to efficiently query external services in their Flink jobs, e.g. large-sized LLM which is +typically deployed in a standalone GPU cluster, etc. + +Furthermore, we have provided comprehensive support to ensure the stability of external service +access. On one hand, we support limiting the number of concurrent requests sent to the external +service to avoid overwhelming it. On the other hand, we have also added retry support to tolerate +temporary unavailability which maybe caused by network jitter or other transient issues. + +### Dependency upgrades + +#### Upgrade commons-lang3 to version 3.18.0 + +##### [FLINK-38193](https://issues.apache.org/jira/browse/FLINK-38193) + +Upgrade org.apache.commons:commons-lang3 from 3.12.0 to 3.18.0 to mitigate CVE-2025-48924. + +#### Upgrade protobuf-java from 3.x to 4.32.1 with compatibility patch for parquet-protobuf + +##### [FLINK-38547](https://issues.apache.org/jira/browse/FLINK-38547) + +Flink now uses protobuf-java 4.32.1 (corresponding to Protocol Buffers version 32), upgrading from +protobuf-java 3.21.7 (Protocol Buffers version 21). This major upgrade enables: + +- **Protobuf Editions Support**: Full support for the new `edition = "2023"` and `edition = "2024"` + syntax introduced in Protocol Buffers v27+. Editions provide a unified approach that combines + proto2 and proto3 functionality with fine-grained feature control. +- **Improved Proto3 Field Presence**: Better handling of optional fields in proto3 without the + limitations of older protobuf versions, eliminating the need to set `protobuf.read-default-values` + to `true` for field presence checking. +- **Enhanced Performance**: Leverages performance improvements and bug fixes from 11 Protocol + Buffers releases (versions 22-32). +- **Modern Protobuf Features**: Access to newer protobuf capabilities including Edition 2024 + features and improved runtime behavior. + +Users with existing proto2 and proto3 `.proto` files will continue to work without changes. + + +### Core + +#### Set security.ssl.algorithms default value to modern cipher suite + +### [FLINK-39022](https://issues.apache.org/jira/browse/FLINK-39022) + +A JDK update (affecting JDK 11.0.30+, 17.0.18+, 21.0.10+, and 24+) disabled `TLS_RSA_*` cipher suites. +This was done to support forward-secrecy (RFC 9325) and comply with the IETF Draft on *Deprecating Obsolete Key Exchange Methods in TLS*. + +To support these and future JDK versions, the default value for the Flink configuration option `security.ssl.algorithms` has been changed to a modern, widely available cipher suite: + +`TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384` + +This default provides strong security and wide compatibility. You can customize the cipher suites using the `security.ssl.algorithms` configuration option if your environment has different requirements. +If these cipher suites are not supported on your setup, you will see that Flink processes will not be able to connect to each other.