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sysvar: debug expressions (#9998) #10055

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Aug 18, 2022
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sysvar: debug expressions (#9998) #10055

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2 changes: 1 addition & 1 deletion system-variables.md
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Expand Up @@ -1414,7 +1414,7 @@ For a system upgraded to v5.0 from an earlier version, if you have not modified
- Type: Boolean
- Default value: `OFF`
- This variable controls the way commit TS is calculated for async commit. By default (with the `OFF` value), the two-phase commit requests a new TS from the PD server and uses the TS to calculate the final commit TS. In this situation, linearizability is guaranteed for all the concurrent transactions.
- If you set this variable to `ON`, the TS fetched from the PD server is saved, with the cost that only causal consistency is guaranteed but not linearizability. For more details, see the blog post [Async Commit, the Accelerator for Transaction Commit in TiDB 5.0](https://en.pingcap.com/blog/async-commit-the-accelerator-for-transaction-commit-in-tidb-5-0/).
- If you set this variable to `ON`, the process of fetching TS from the PD server is skipped, with the cost that only causal consistency is guaranteed but not linearizability. For more details, see the blog post [Async Commit, the Accelerator for Transaction Commit in TiDB 5.0](https://en.pingcap.com/blog/async-commit-the-accelerator-for-transaction-commit-in-tidb-5-0/).
- For scenarios that require only causal consistency, you can set this variable to `ON` to improve performance.

### tidb_hash_join_concurrency
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