升级到8.1之后，多了1个慢查询，sql语句就一个“；”（分号），无用户信息。

TiDBer_rrt4FOef · 2024 年6 月 13 日 02:08

【 TiDB 使用环境】生产环境
【 TiDB 版本】v8.1.0
【复现路径】
【遇到的问题】
今日凌晨0点左右（6月13日）对tidb做了版本升级，从v6.5.0 升级到了 v8.1.0，不停机升级。
升级过程一切正常，没有任何报错信息，升级完成后，连接正常，各系统也运行稳定。

早上在Dashboard上观察慢查询时，发现多了一个奇怪的慢查询。
语句就一个分号“；”，而且过10几分钟就执行一次，最多内存也忽大忽小。基本信息里也不显示执行数据库、执行用户名和客户端地址。
查询了INFORMATION_SCHEMA的CLUSTER_SLOW_QUERY,这个语句是升级完后才出现的，升级前慢查询里没有这个语句。
这是数据库自动执行的吗？这个现象正常吗？

【附件：截图/日志/监控】

zhaokede · 2024 年6 月 13 日 03:00

看索引名这一行，有一个tidb_background_subtask:idx_exec_id，是不是数据库的后台子任务，在做索引优化

zhaokede · 2024 年6 月 13 日 03:00

idx_exec_id：这部分可能与索引执行有关。它可能是用于标识某个特定索引创建、修改或删除操作的标识符

Kongdom · 2024 年6 月 13 日 05:46

只有一个分号，然后执行计划里还有HashJoin?能发一下完整的执行计划么？

TiDBer_rrt4FOef · 2024 年6 月 13 日 07:55

“；”这样的sql大概有六十多条慢sql记录，大部分记录里都没有执行计划。
看警告这一栏里，好多都是类似如下信息

Analyze use auto adjusted sample rate 0.034xxx for db.table_name,reason to use this rate is "Row count is stats_meta is smaller compared with the row count got by PD,use min(1,15000/4.385493e+06) as the sample-rate=0.034xxxxxx"

猜测应该是数据库本身的一些分析任务，执行完之后，今天下午没有再出现在慢查询里了。

林夕一指 · 2024 年6 月 13 日 09:33

看着内容像是收集统计信息的，可是我咋记得统计信息的后台任务是sql的呀就一个；着实不知道

Kongdom · 2024 年6 月 14 日 01:07

只能等原厂大佬来看看了。

Kongdom · 2024 年6 月 14 日 01:24

比如这个执行计划，会不会是sql太长，然后sql里有换行，截断之后就只有换行的分号了

小龙虾爱大龙虾 · 2024 年6 月 14 日 02:47

去文件中看看呢

TiDBer_mra9oJ0k · 2024 年6 月 14 日 04:46

我7.5升完8.1也有这个情况

这里介绍不了我 · 2024 年6 月 14 日 09:20

关注学习一下

ziptoam · 2024 年6 月 15 日 02:35

这个问题很奇怪，即使是索引或者分析等数据库自身产生的任务，也不合适用这种不严谨的表现方式

zhaokede · 2024 年6 月 15 日 03:22

就是系统自动的索引优化分析后台任务

扬仔_tidb · 2024 年6 月 15 日 08:41

会不会是dashboard的显示bug呢

h5n1 · 2024 年6 月 15 日 09:34

https://github.com/pingcap/tidb/issues/52743

Kongdom · 2024 年6 月 15 日 13:51

原来真的是个BUG，可以蹲修复版本了。

v8.1.0版本已经确认有这个问题

zhanggame1 · 2024 年6 月 16 日 13:01

显然像个bug

Hacker007 · 2024 年6 月 17 日 01:07

复制原始sql也只有一个;?

友利奈绪 · 2024 年6 月 17 日 01:25

等后续修复吧2333

Jellybean · 2024 年6 月 17 日 01:37

从“是否为内部SQL查询“的值为1，这里的信息可以知道是tidb集群内部的语句，是集群自身的问题，非业务侧SQL。

解决方法如前面大佬提到的issue链接，等官方修复后再调整下，保持关注。

github.com/pingcap/tidb

empty query in slow log

opened 10:52AM - 14 May 24 UTC

crazycs520

type/bug sig/diagnosis

## Bug Report Please answer these questions before submitting your issue. Tha…nks! ### 1. Minimal reproduce step (Required) ```sql set @@tidb_slow_log_threshold=0; ``` <img width="2105" alt="image" src="https://github.com/pingcap/tidb/assets/26020263/d6320e64-6a75-4b6c-b724-6a15b6150fb0"> related slow log: ```log # Time: 2024-05-14T10:46:16.744456542Z # Txn_start_ts: 449756151429201928 # Query_time: 15.671098186 # Parse_time: 0 # Compile_time: 0.001440327 # Rewrite_time: 0.00028654 # Optimize_time: 0.000975736 # Wait_TS: 0.000020672 # Cop_time: 15.669230206 Process_time: 0.000263148 Wait_time: 0.000087955 Backoff_time: 15.588 Request_count: 2 Total_keys: 36 Get_snapshot_time: 0.000 Rocksdb_key_skipped_count: 32 Rocksdb_block_cache_hit_count: 28 # Index_names: [tidb_background_subtask:idx_exec_id,tidb_global_task:state] # Is_internal: true # Digest: 8e00fe5c3677d581b104159ff91d824e3be8160c4e4be058288db681abd1a134 # Stats: tidb_global_task:pseudo[10000;0],tidb_background_subtask:pseudo[10000;0] # Num_cop_tasks: 2 # Cop_proc_avg: 0.000131574 Cop_proc_p90: 0.000189195 Cop_proc_max: 0.000189195 Cop_proc_addr: 192.168.180.13:23360 # Cop_wait_avg: 4.3977e-05 Cop_wait_p90: 4.5169e-05 Cop_wait_max: 4.5169e-05 Cop_wait_addr: 192.168.180.13:23360 # Cop_backoff_regionMiss_total_times: 35 Cop_backoff_regionMiss_total_time: 14.01 Cop_backoff_regionMiss_max_time: 14.01 Cop_backoff_regionMiss_max_addr: 192.168.180.13:23360 Cop_backoff_regionMiss_avg_time: 14.01 Cop_backoff_regionMiss_p90_time: 14.01 # Cop_backoff_regionScheduling_total_times: 10 Cop_backoff_regionScheduling_total_time: 1.51 Cop_backoff_regionScheduling_max_time: 1.51 Cop_backoff_regionScheduling_max_addr: 192.168.180.13:23360 Cop_backoff_regionScheduling_avg_time: 1.51 Cop_backoff_regionScheduling_p90_time: 1.51 # Cop_backoff_tikvRPC_total_times: 1 Cop_backoff_tikvRPC_total_time: 0.068 Cop_backoff_tikvRPC_max_time: 0.068 Cop_backoff_tikvRPC_max_addr: 192.168.180.13:23360 Cop_backoff_tikvRPC_avg_time: 0.068 Cop_backoff_tikvRPC_p90_time: 0.068 # Mem_max: 17016 # Prepared: false # Plan_from_cache: false # Plan_from_binding: false # Has_more_results: false # KV_total: 0 # PD_total: 0 # Backoff_total: 0 # Write_sql_response_total: 0 # Result_rows: 0 # Warnings: [{"Level":"Note","Message":"[st,idx_exec_id] remain after pruning paths for st given Prop{SortItems: [], TaskTp: rootTask}","IsExtra":true},{"Level":"Note","Message":"[t,state] remain after pruning paths for t given Prop{SortItems: [], TaskTp: rootTask}","IsExtra":true}] # Succ: true # IsExplicitTxn: false # IsSyncStatsFailed: false # Plan: tidb_decode_plan('gSawMAkxNF8xMwkwCTEJbXlzcWwudGlkYl9nbG9iYWxfdGFzay5wcmlvcml0eSwgWiEAKGNyZWF0ZV90aW1lYiQAEGlkCTAJASJYOjE1LjdzLCBsb29wczoxCTAgQnl0ZXMRCBgKMQkzXzE1bpAADGlkLCBaigABsAxfa2V5ZiEABHlwZqQADHN0YXRuHgAEZXBiWACGJAEgb25jdXJyZW5jZp0AjkgBJHRhcmdldF9zY28ByRxDb2x1bW4jMyEwSl0BCCwgQxl3WDpPRkYJNC43MSBLQglOL0EKMgk2XzE2JWogZ3JvdXAgYnk6WlgBIXMkZnVuY3M6bWF4KB0lDGJhY2sBPRRuZF9zdWIhfwAuHeoIKS0+FaIALA1BHGZpcnN0cm93LkYAL 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') # Plan_digest: 19251e4d0852c3daee269dcb983554a856b9ab56b15a27ac9c282faeeb7e2e53 # Binary_plan: tidb_decode_binary_plan('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') # Resource_group: default ; ``` ### 2. What did you expect to see? (Required) ### 3. What did you see instead (Required) ### 4. What is your TiDB version? (Required) nightly: 4b91fee6af2b1859d223670130e5c8bf3f400026

github.com/pingcap/tidb

Empty slow query text for a stmt that reads tidb_mdl_info

opened 02:06AM - 19 Apr 24 UTC

ekexium

type/bug sig/sql-infra severity/major may-affects-5.4 may-affects-6.1 may-affects-6.5 may-affects-7.1 may-affects-7.5 affects-8.1

## Bug Report Please answer these questions before submitting your issue. Tha…nks! ### 1. Minimal reproduce step (Required) Unknown. This seems to be an internal SQL. ### 2. What did you expect to see? (Required) Slow query should display the query text. ### 3. What did you see instead (Required) <img width="878" alt="image" src="https://github.com/pingcap/tidb/assets/31720476/ded13398-f5e0-4c5e-8e26-f5a3a3358a04"> The query text is empty. ### 4. What is your TiDB version? (Required) master(8d9e67b37dea759db0980aeddf4da967bf93e83e)