From 44fee5e4e719a739fd87347a9e02730e69e1d0aa Mon Sep 17 00:00:00 2001 From: EricZequan <110292382+EricZequan@users.noreply.github.com> Date: Mon, 16 Dec 2024 19:21:06 +0800 Subject: [PATCH] This is an automated cherry-pick of #19694 Signed-off-by: ti-chi-bot --- optimizer-fix-controls.md | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/optimizer-fix-controls.md b/optimizer-fix-controls.md index 5848183017aec..93f6b5777f08a 100644 --- a/optimizer-fix-controls.md +++ b/optimizer-fix-controls.md @@ -83,9 +83,21 @@ SET SESSION tidb_opt_fix_control = '44262:ON,44389:ON'; - Possible values: `ON`, `OFF` - This variable controls whether the optimizer explores enforced plans during query optimization after finding an unenforced plan. +<<<<<<< HEAD ### [`52869`](https://github.com/pingcap/tidb/issues/52869) New in v8.1.0 - Default value: `OFF` - Possible values: `ON`, `OFF` - As stated in the **Note** of [Explain Statements Using Index Merge](/explain-index-merge.md#examples), if the optimizer can choose the single index scan method (other than full table scan) for a query plan, the optimizer will not automatically use index merge. - You can remove this limitation by enabling this fix control. Removing this limitation enables the optimizer to choose index merge automatically in more queries, but might cause the optimizer to ignore the optimal execution plans. Therefore, it is recommended to conduct sufficient tests on actual use cases before removing this limitation to make sure that it will not cause performance regressions. +======= +### [`56318`](https://github.com/pingcap/tidb/issues/56318) + +> **Note:** +> +> This is only available for [TiDB Cloud Serverless](https://docs.pingcap.com/tidbcloud/select-cluster-tier#tidb-cloud-serverless). + +- Default value: `ON` +- Possible values: `ON`, `OFF` +- This variable controls whether to avoid calculating the heavy expression used in the `ORDER BY` statement twice. +>>>>>>> 97f985443e (cloud: fix control add 56318 (#19694))