tidb: mark tidb_mpp_store_fail_ttl as deprecated
#21410
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Signed-off-by: gengliqi <[email protected]>
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Summary of Changes
Hello @gengliqi, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request updates the documentation for the tidb_mpp_store_fail_ttl system variable, reflecting its deprecation and a change in its default behavior. This change signifies an improvement in how TiDB handles newly started TiFlash nodes, removing the necessity for a waiting period to prevent query failures.
Highlights
- Documentation Update: The
tidb_mpp_store_fail_ttlsystem variable is now officially marked as deprecated in the documentation. - Variable Behavior Change: Starting from TiDB v9.0.0, the default value of
tidb_mpp_store_fail_ttlwill be fixed to0s, meaning no delay is imposed for newly started TiFlash nodes. - Rationale for Change: The deprecation and change in default value are due to improvements that eliminate the need for an additional delay to prevent query failures when new TiFlash nodes come online.
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system-variables.md
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| - Default value: `60s` | ||
| - The newly started TiFlash node does not provide services. To prevent queries from failing, TiDB limits the tidb-server sending queries to the newly started TiFlash node. This variable indicates the time range in which the newly started TiFlash node is not sent requests. | ||
| - Default value: Before v9.0.0, the default value is `60s`. Starting from v9.0.0, the default value is `0s`. | ||
| - The newly started TiFlash node does not provide services. To prevent queries from failing, TiDB limits the tidb-server from sending queries to the newly started TiFlash nodes. This variable indicates the time range during which the newly started TiFlash node does not send requests. |
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The current description is a bit confusing and contains a factual error. The phrase the newly started TiFlash node does not send requests is incorrect; the node receives requests. The original passive voice is not sent requests was more accurate, but we can improve clarity with active voice.12
Here's a clearer and more concise version that explains the variable's purpose.
Style Guide References
| - The newly started TiFlash node does not provide services. To prevent queries from failing, TiDB limits the tidb-server from sending queries to the newly started TiFlash nodes. This variable indicates the time range during which the newly started TiFlash node does not send requests. | |
| - To prevent query failures when a TiFlash node starts, TiDB avoids sending queries to it for a period of time. This variable controls that time period. |
Footnotes
| - Scope: SESSION | GLOBAL | ||
| - Persists to cluster: Yes | ||
| - Applies to hint [SET_VAR](/optimizer-hints.md#set_varvar_namevar_value): No | ||
| - Type: Duration | ||
| - Default value: `60s` | ||
| - The newly started TiFlash node does not provide services. To prevent queries from failing, TiDB limits the tidb-server sending queries to the newly started TiFlash node. This variable indicates the time range in which the newly started TiFlash node is not sent requests. | ||
| - Default value: Before v9.0.0, the default value is `60s`. Starting from v9.0.0, the default value is `0s`. |
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To improve readability and avoid repetition, you can make this description more concise.1
Style Guide References
| - Default value: Before v9.0.0, the default value is `60s`. Starting from v9.0.0, the default value is `0s`. | |
| - Default value: `60s` before v9.0.0; `0s` from v9.0.0. |
Footnotes
Signed-off-by: gengliqi <[email protected]>
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
First-time contributors' checklist
What is changed, added or deleted? (Required)
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