reference/titan: add titan docs #2494
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Signed-off-by: Connor1996 <[email protected]>
Signed-off-by: Connor1996 <[email protected]>
TomShawn
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reference/titan/design.md
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| # Titan 设计文档 | |||
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请确认是否需要在官网展示设计文档。一般官网文档只展示用户文档。
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稍微精简下了这个文档，让它更符合简介文档的定位
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@Connor1996 Please also involve a technical review, thanks! |
Signed-off-by: Connor1996 <[email protected]>
reference/titan/overview.md
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| ### 传统 GC | ||
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| 在设计 GC 的时候有两个主要的问题需要考虑： |
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@Connor1996 @yiwu-arbug 是否是从开发者设计的角度介绍 Titan 的设计思路和实现细节，个人觉得对于用户文档来说太详细和复杂了，用户是否真的需要去了解开发者是如何去设计的以及内部的各种实现机制呢？建议这些内容在博客中展示。
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
Co-Authored-By: TomShawn <[email protected]>
reference/titan/overview.md
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| GC 的方式就是对于这些选中的 BlobFile 文件，依次通过查询其中每个 value 相应的 key 的 blob index 是否存在或者更新来确定该 value 是否作废，最终将未作废的 value 归并排序生成新的 BlobFile，并将这些 value 更新后的 blob index 通过 WriteCallback 或者 MergeOperator 的方式写回到 SST 中。在完成 GC 后，这些原来的 BlobFile 文件并不会立即被删除，Titan 会在写回 blob index 后记录 RocksDB 最新的 sequence number，等到最旧 snapshot 的 sequence 超过这个记录的 sequence number 时 BlobFile 才能被删除。这个是因为在写回 blob index 后，还是可能通过之前的 snapshot 访问到老的 blob index，因此需要确保没有 snapshot 会访问到这个老的 blob index 后才能安全删除相应 BlobFile。 | ||
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| ### Level-Merge |
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@Connor1996 Please confirm and unify Level-Merge or Level Merge.
TomShawn
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cherry pick to release-4.0 in PR #3045 |
Co-authored-by: Connor <[email protected]>
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NOTE: Please also align titan-configuration.md → storage-engine/titan-configuration.md AND titan-configuration.md → storage-engine/titan-configuration.md in https://github.com/pingcap/docs-cn/pull/3574/files. @TomShawn |
Get it. Thanks! |
TomShawn
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Signed-off-by: Connor1996 [email protected]
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