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docs: fix schema_unused_indexes source table and restart-scope wording #23891

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docs: fix schema_unused_indexes source table and restart-scope wording #23891

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docs: fix schema_unused_indexes source table and restart scope
yahonda Sep 16, 2026
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best-practices: clarify per-instance restart scope for schema_unused_…
yahonda Sep 18, 2026
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6 changes: 3 additions & 3 deletions best-practices/index-management-best-practices.md
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Expand Up @@ -167,7 +167,7 @@ By using `CLUSTER_TIDB_INDEX_USAGE`, you can gain a global perspective on index

## Identify unused indexes using `schema_unused_indexes`

Manually analyzing index usage data can be time-consuming. To simplify this process, TiDB provides [`schema_unused_indexes`](/sys-schema/sys-schema-unused-indexes.md), a system view that lists indexes that have not been used since the database is last restarted.
Manually analyzing index usage data can be time-consuming. To simplify this process, TiDB provides [`schema_unused_indexes`](/sys-schema/sys-schema-unused-indexes.md), a system view that lists indexes that have not been accessed on any TiDB instance since that instance's last restart.

This provides a quick way for you to do the following:

Expand All @@ -179,7 +179,7 @@ By using `schema_unused_indexes`, you can quickly identify unnecessary indexes a

### How `schema_unused_indexes` works

The `schema_unused_indexes` view is derived from `TIDB_INDEX_USAGE`, meaning it automatically filters out indexes that have recorded zero query activity since the last TiDB restart.
The `schema_unused_indexes` view is derived from `CLUSTER_TIDB_INDEX_USAGE`, meaning it automatically extracts indexes that have not been accessed on any TiDB instance since that instance's last restart.
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To retrieve a list of unused indexes, run the following SQL statement:

Expand All @@ -202,7 +202,7 @@ A result similar to the following is returned:

Take the following points into consideration when you use `schema_unused_indexes`.

#### Indexes are considered unused only since the last restart
#### Indexes are considered unused only since each TiDB instance's last restart

- If a TiDB node restarts, the usage tracking data is reset.
- Ensure the system has been running long enough to capture a representative workload before relying on this data.
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