stale read: update the description of tidb_external_ts (#20667) #20729
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Summary of Changes
This pull request updates the description in stale-read.md to include tidb_enable_external_ts_read alongside tidb_external_ts when specifying an exact point in time for stale reads. This change clarifies that both system variables are needed for this functionality.
Highlights
- Documentation Update: The documentation for stale reads is updated to include
tidb_enable_external_ts_readwhen describing how to specify an exact point in time. - Clarity: The change improves the clarity of the documentation by explicitly mentioning both system variables required for the stale read feature.
Changelog
- stale-read.md
- Updated the description to include
tidb_enable_external_ts_readwhen specifying an exact point in time for stale reads usingtidb_external_ts.
- Updated the description to include
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Code Review
The pull request updates the description of tidb_external_ts in the stale-read.md file. The change adds tidb_enable_external_ts_read to the description, which is useful for stale read operations. Overall, the change is straightforward and improves the documentation.
Merge Readiness
The pull request includes a documentation update that clarifies the usage of tidb_external_ts and tidb_enable_external_ts_read. Given the limited scope and the absence of any identified issues at the medium, high, or critical levels, the pull request appears ready for merging. However, I am unable to approve the pull request, and the users should have others review and approve this code before merging.
| @@ -35,7 +35,7 @@ TiDB provides the methods of performing Stale Read at the statement level, the s | |||
| - Session level | |||
| - Specifying a time range: In a session, if you need TiDB to read the data as new as possible within a time range in subsequent queries without violating the isolation level, you can specify the time range by setting the `tidb_read_staleness` system variable. For detailed usage, refer to [`tidb_read_staleness`](/tidb-read-staleness.md). | |||
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| Besides, TiDB provides a way to specify an exact point in time by setting the [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640) system variable on session or global level. For detailed usage, refer to [Perform Stale Read Using `tidb_external_ts`](/tidb-external-ts.md). | |||
| Besides, TiDB provides a way to specify an exact point in time at the session or global level by setting the [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640) and [`tidb_enable_external_ts_read`](/system-variables.md#tidb_enable_external_ts_read-new-in-v640) system variables. For detailed usage, refer to [Perform Stale Read Using `tidb_external_ts`](/tidb-external-ts.md). | |||
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Consider adding a brief explanation of why tidb_enable_external_ts_read is also required, perhaps in the form of an inline comment in the code suggestion. This will help users understand the relationship between the two variables at a glance.
| Besides, TiDB provides a way to specify an exact point in time at the session or global level by setting the [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640) and [`tidb_enable_external_ts_read`](/system-variables.md#tidb_enable_external_ts_read-new-in-v640) system variables. For detailed usage, refer to [Perform Stale Read Using `tidb_external_ts`](/tidb-external-ts.md). | |
| Besides, TiDB provides a way to specify an exact point in time at the session or global level by setting the [`tidb_external_ts`](/system-variables.md#tidb_external_ts-new-in-v640) and [`tidb_enable_external_ts_read`](/system-variables.md#tidb_enable_external_ts_read-new-in-v640) system variables. // tidb_enable_external_ts_read must also be enabled to use tidb_external_ts | |
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/approve |
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[APPROVALNOTIFIER] This PR is APPROVED This pull-request has been approved by: Oreoxmt The full list of commands accepted by this bot can be found here. The pull request process is described here
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This is an automated cherry-pick of #20667
What is changed, added or deleted? (Required)
close #20611
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Tips for choosing the affected version(s):
By default, CHOOSE MASTER ONLY so your changes will be applied to the next TiDB major or minor releases. If your PR involves a product feature behavior change or a compatibility change, CHOOSE THE AFFECTED RELEASE BRANCH(ES) AND MASTER.
For details, see tips for choosing the affected versions.
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Do your changes match any of the following descriptions?