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cached-tables: add description about mysql.table_cache_meta table #10310

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merged 4 commits into from
Dec 21, 2022
Merged

cached-tables: add description about mysql.table_cache_meta table #10310

merged 4 commits into from
Dec 21, 2022

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tiancaiamao
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@tiancaiamao tiancaiamao commented Jun 29, 2022 •
edited by Oreoxmt
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First-time contributors' checklist

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Close #10087

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ti-chi-bot commented Jun 29, 2022 •
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[REVIEW NOTIFICATION]

This pull request has been approved by:

  • Oreoxmt
  • tangenta

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
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@ti-chi-bot ti-chi-bot requested a review from TomShawn June 29, 2022 08:10
@ti-chi-bot ti-chi-bot added missing-translation-status This PR does not have translation status info. size/S Denotes a PR that changes 10-29 lines, ignoring generated files. labels Jun 29, 2022
@Oreoxmt Oreoxmt added area/sql-infra Indicates that the Issue or PR belongs to the area of sql-infra and sql-metadata. translation/doing This PR’s assignee is translating this PR. type/enhancement The issue or PR belongs to an enhancement. labels Jun 29, 2022
@ti-chi-bot ti-chi-bot removed the missing-translation-status This PR does not have translation status info. label Jun 29, 2022
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We may need to update https://docs.pingcap.com/zh/tidb/dev/mysql-schema as well.

Oreoxmt
Oreoxmt reviewed Jun 29, 2022
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cached-tables.md Outdated
@@ -177,6 +177,22 @@ SELECT * FROM users;
>
> 缓存表的写入延时高是受到实现的限制。存在多个 TiDB 实例时，一个 TiDB 实例并不知道其它的 TiDB 实例是否缓存了数据，如果该实例直接修改了表数据，而其它 TiDB 实例依然读取旧的缓存数据，就会读到错误的结果。为了保证数据正确性，缓存表的实现使用了一套基于 lease 的复杂机制：读操作在缓存数据同时，还会对于缓存设置一个有效期，也就是 lease。在 lease 过期之前，无法对数据执行修改操作。因为修改操作必须等待 lease 过期，所以会出现写入延迟。

缓存表相关的元信息存储在 `mysql.table_cache_meta` 表中。这张表记录了所有缓存表的 `tid`，当前状态 `lock_type`，以及 `lease` 相关的信息。这张表仅供 TiDB 内部使用，用户修改可能导致不可预期的错误。
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@Oreoxmt Oreoxmt Jun 29, 2022 •
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Suggested change
缓存表相关的元信息存储在 `mysql.table_cache_meta` 表中。这张表记录了所有缓存表的 `tid`，当前状态 `lock_type`，以及 `lease` 相关的信息。这张表仅供 TiDB 内部使用，用户修改可能导致不可预期的错误。
缓存表相关的元信息存储在 `mysql.table_cache_meta` 表中。这张表记录了所有缓存表的 `tid`，当前状态 `lock_type`，以及 `lease` 相关的信息。
> **注意：**
>
> 这张表仅供 TiDB 内部使用，用户修改可能导致不可预期的错误。

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Why not tell this to the user?

tangenta
tangenta reviewed Jun 29, 2022
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@TomShawn TomShawn added the ONCALL Relates to documentation oncall. label Jun 29, 2022
tiancaiamao and others added 2 commits June 30, 2022 14:55
@tiancaiamao @tangenta
Update cached-tables.md
cf26a78 
Co-authored-by: tangenta <tangenta@126.com>
@tiancaiamao
address comment
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@TomShawn TomShawn self-assigned this Jul 6, 2022
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Oreoxmt approved these changes Sep 9, 2022
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LGTM

@ti-chi-bot ti-chi-bot added the status/LGT1 Indicates that a PR has LGTM 1. label Sep 9, 2022
@Oreoxmt Oreoxmt requested a review from tangenta October 13, 2022 03:00
@ti-chi-bot ti-chi-bot added status/LGT2 Indicates that a PR has LGTM 2. and removed status/LGT1 Indicates that a PR has LGTM 1. labels Oct 13, 2022
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/merge

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This pull request has been accepted and is ready to merge.

Commit hash: 63809b8

@ti-chi-bot ti-chi-bot added the status/can-merge Indicates a PR has been approved by a committer. label Dec 21, 2022
@ti-chi-bot ti-chi-bot merged commit 686178a into pingcap:master Dec 21, 2022
@ti-chi-bot ti-chi-bot mentioned this pull request Dec 21, 2022
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In response to a cherrypick label: new pull request created to branch release-6.2: #12343.

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In response to a cherrypick label: new pull request created to branch release-6.3: #12344.

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In response to a cherrypick label: new pull request created to branch release-6.4: #12345.

ti-chi-bot added a commit that referenced this pull request Dec 21, 2022
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cached-tables: add description about mysql.table_cache_meta table (#…
38d6bce 
…10310) (#12343)
ti-chi-bot added a commit that referenced this pull request Dec 21, 2022
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cached-tables: add description about mysql.table_cache_meta table (#…
95eca89 
…10310) (#12344)
ti-chi-bot added a commit that referenced this pull request Dec 21, 2022
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cached-tables: add description about mysql.table_cache_meta table (#…
484c4a3 
…10310) (#12345)
@TomShawn TomShawn mentioned this pull request Dec 22, 2022
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@TomShawn TomShawn added translation/done This PR has been translated from English into Chinese and updated to pingcap/docs-cn in a PR. and removed translation/doing This PR’s assignee is translating this PR. labels Dec 22, 2022
This was referenced Dec 23, 2022
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@tangenta tangenta tangenta approved these changes

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suggest add info about table mysql.table_cache_meta
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