You are viewing a plain text version of this content. The canonical link for it is here.
Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2022/06/28 02:27:42 UTC
[GitHub] [flink] Myasuka commented on a diff in pull request #19998: [FLINK-27822][docs-zh] Translate the doc of checkpoint/savepoint guar…
Myasuka commented on code in PR #19998:
URL: https://github.com/apache/flink/pull/19998#discussion_r907969227
##########
docs/content.zh/docs/ops/state/checkpoints_vs_savepoints.md:
##########
@@ -24,72 +24,65 @@ specific language governing permissions and limitations
under the License.
-->
-# Checkpoints vs. Savepoints
+<a name="checkpoints-vs-savepoints"></a>
-## Overview
+# Checkpoints 与 Savepoints
-Conceptually, Flink's [savepoints]({{< ref "docs/ops/state/savepoints" >}}) are different from [checkpoints]({{< ref "docs/ops/state/checkpoints" >}})
-in a way that's analogous to how backups are different from recovery logs in traditional database systems.
+<a name="overview"></a>
-The primary purpose of checkpoints is to provide a recovery mechanism in case of unexpected job failures.
-A [checkpoint's lifecycle]({{< ref "docs/dev/datastream/fault-tolerance/checkpointing" >}}) is managed by Flink,
-i.e. a checkpoint is created, owned, and released by Flink - without user interaction.
-Because checkpoints are being triggered often, and are relied upon for failure recovery, the two main design goals for the checkpoint implementation are
-i) being as lightweight to create and ii) being as fast to restore from as possible.
-Optimizations towards those goals can exploit certain properties, e.g., that the job code doesn't change between the execution attempts.
+## 概述
+
+从概念上讲，Flink 的 [savepoints]({{< ref "docs/ops/state/savepoints" >}}) 与 [checkpoints]({{< ref "docs/ops/state/checkpoints" >}}) 的不同之处类似于传统数据库系统中的备份与恢复日志之间的差异。
+
+Checkpoints 的主要目的是为意外失败的作业提供恢复机制。
+[Checkpoint 的生命周期]({{< ref "docs/dev/datastream/fault-tolerance/checkpointing" >}}) 由 Flink 管理，
+即 Flink 创建，管理和删除 checkpoint - 无需用户交互。
+由于 checkpoint 被经常触发，且被用于作业恢复，所以 Checkpoint 的实现有两个设计目标：i）轻量级创建和 ii）尽可能快地恢复。 可能会利用某些特定的属性来达到这个目标，例如， 作业的代码在执行尝试时不会改变。
{{< hint info >}}
-- Checkpoints are automatically deleted if the application is terminated by the user
-(except if checkpoints are explicitly configured to be retained).
-- Checkpoints are stored in state backend-specific (native) data format (may be incremental depending on the specific backend).
+- 在用户终止作业后，会自动删除 Checkpoint（除非明确配置为保留的 Checkpoint）。
+- Checkpoint 以状态后端特定的（原生的）数据格式存储（有些状态后端可能是增量的）。
{{< /hint >}}
-Although [savepoints]({{< ref "docs/ops/state/savepoints" >}}) are created internally with the same mechanisms as
-checkpoints, they are conceptually different and can be a bit more expensive to produce and restore from. Their design focuses
-more on portability and operational flexibility, especially with respect to changes to the job.
-The use case for savepoints is for planned, manual operations. For example, this could be an update of your Flink version, changing your job graph, and so on.
+尽管 [savepoints]({{< ref "docs/ops/state/savepoints" >}}) 在内部使用与 checkpoints 相同的机制创建，但它们在概念上有所不同，并且生成和恢复的成本可能会更高一些。Savepoints的设计更侧重于可移植性和操作灵活性，尤其是在 job 变更方面。Savepoint 的用例是针对计划中的、手动的运维。例如，可能是更新你的 Flink 版本，更改你的作业图等等。
{{< hint info >}}
-- Savepoints are created, owned and deleted solely by the user.
-That means, Flink does not delete savepoints neither after job termination nor after
-restore.
-- Savepoints are stored in a state backend independent (canonical) format (Note: Since Flink 1.15, savepoints can be also stored in
-the backend-specific [native]({{< ref "docs/ops/state/savepoints" >}}#savepoint-format) format which is faster to create
-and restore but comes with some limitations.
+- Savepoint 仅由用户创建、拥有和删除。这意味着 Flink 在作业终止后和恢复后都不会删除 savepoint。
+- Savepoint 以状态后端独立的（标准的）数据格式存储（注意：从 Flink 1.15 开始，savepoint 也可以以后端特定的[原生]({{< ref "docs/ops/state/savepoints" >}}#savepoint-format)格式存储，这种格式创建和恢复速度更快，但有一些限制）。
{{< /hint >}}
-### Capabilities and limitations
-The following table gives an overview of capabilities and limitations for the various types of savepoints and
-checkpoints.
-- ✓ - Flink fully support this type of the snapshot
-- x - Flink doesn't support this type of the snapshot
-- ! - While these operations currently work, Flink doesn't officially guarantee support for them, so there is a certain level of risk associated with them
+<a name="capabilities-and-limitations"></a>
+
+### 功能和限制
-| Operation | Canonical Savepoint | Native Savepoint | Aligned Checkpoint | Unaligned Checkpoint |
+下表概述了各种类型的 savepoint 和 checkpoint 的功能和限制。
+- ✓ - Flink 完全支持这种类型的快照
+- x - Flink 不支持这种类型的快照
+- ! - 虽然这些操作目前有效，但 Flink 并未正式保证对它们的支持，因此它们存在一定程度的风险
+
+| 操作 | 标准 Savepoint | 原生 Savepoint | 对齐 Checkpoint | 非对齐 Checkpoint |
|:----------------------------------|:--------------------|:-----------------|:-------------------|:---------------------|
-| State backend change | ✓ | x | x | x |
-| State Processor API (writing) | ✓ | x | x | x |
-| State Processor API (reading) | ✓ | ! | ! | x |
-| Self-contained and relocatable | ✓ | ✓ | x | x |
-| Schema evolution | ✓ | ! | ! | ! |
-| Arbitrary job upgrade | ✓ | ✓ | ✓ | x |
-| Non-arbitrary job upgrade | ✓ | ✓ | ✓ | x |
-| Flink minor version upgrade | ✓ | ✓ | ✓ | x |
-| Flink bug/patch version upgrade | ✓ | ✓ | ✓ | ✓ |
-| Rescaling | ✓ | ✓ | ✓ | ✓ |
-
-- [State backend change]({{< ref "docs/ops/state/state_backends" >}}) - configuring a different State Backend than was used when taking the snapshot.
-- [State Processor API (writing)]({{< ref "docs/libs/state_processor_api" >}}#writing-new-savepoints) - the ability to create a new snapshot of this type via the State Processor API.
-- [State Processor API (reading)]({{< ref "docs/libs/state_processor_api" >}}#reading-state) - the ability to read states from an existing snapshot of this type via the State Processor API.
-- Self-contained and relocatable - the one snapshot folder contains everything it needs for recovery
-and it doesn't depend on other snapshots which means it can be easily moved to another place if needed.
-- [Schema evolution]({{< ref "docs/dev/datastream/fault-tolerance/serialization/schema_evolution" >}}) - the *state* data type can be changed if it uses a serializer that supports schema evolution (e.g., POJOs and Avro types)
-- Arbitrary job upgrade - the snapshot can be restored even if the [partitioning types]({{< ref "docs/dev/datastream/operators/overview" >}}#physical-partitioning)(rescale, rebalance, map, etc.)
-or in-flight record types for the existing operators have changed.
-- Non-arbitrary job upgrade - restoring the snapshot is possible with updated operators if the job graph topology and in-flight record types remain unchanged.
-- Flink minor version upgrade - restoring a snapshot taken with an older minor version of Flink (1.x → 1.y).
-- Flink bug/patch version upgrade - restoring a snapshot taken with an older patch version of Flink (1.14.x → 1.14.y).
-- Rescaling - restoring the snapshot with a different parallelism than was used during the snapshot creation.
+| 更换状态后端 | ✓ | x | x | x |
+| State Processor API (写) | ✓ | x | x | x |
+| State Processor API (读) | ✓ | ! | ! | x |
+| 自包含和可移动 | ✓ | ✓ | x | x |
+| Schema 变更 | ✓ | ! | ! | ! |
+| 任意 job 升级 | ✓ | ✓ | ✓ | x |
+| 非任意 job 升级 | ✓ | ✓ | ✓ | x |
+| Flink 小版本升级 | ✓ | ✓ | ✓ | x |
+| Flink bug/patch 版本升级 | ✓ | ✓ | ✓ | ✓ |
+| 伸缩 | ✓ | ✓ | ✓ | ✓ |
Review Comment:
`Rescaling`感觉翻译成`扩缩容`是不是更好理解一些？
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: issues-unsubscribe@flink.apache.org
For queries about this service, please contact Infrastructure at:
users@infra.apache.org