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tidb: mark tidb_mpp_store_fail_ttl as deprecated #21410

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Nov 6, 2025
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tidb: mark tidb_mpp_store_fail_ttl as deprecated #21410

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10a1483
deprecate tidb_mpp_store_fail_ttl
gengliqi Jul 16, 2025
967759c
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gengliqi Jul 16, 2025
14d1979
Update system-variables.md
gengliqi Jul 16, 2025
ebab97c
Update system-variables.md
qiancai Nov 4, 2025
0c267f5
minor wording updates
qiancai Nov 4, 2025
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8 changes: 6 additions & 2 deletions system-variables.md
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Expand Up @@ -4079,12 +4079,16 @@ As shown in this diagram, when [`tidb_enable_paging`](#tidb_enable_paging-new-in

### tidb_mpp_store_fail_ttl

> **Warning:**
>
> Starting from v9.0.0, this variable is deprecated. Its value will be fixed to `0s`, meaning TiDB no longer waits before sending queries to newly started TiFlash nodes, as additional delay is no longer necessary to prevent query failures.

- 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`.
- 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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medium

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

Suggested change
- 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

  1. Documentation should be clear, simple, complete, readable, and technically accurate. (link) ↩

  2. Avoid passive voice where possible to improve clarity. (link) ↩


### tidb_multi_statement_mode <span class="version-mark">New in v4.0.11</span>

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