tidb dashboard 看到很多和InformationSchema有关的超慢查询

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1

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  • 【TiDB 版本】：v4.0.4
  • 【问题描述】：tidb dashboard 看到很多和InformationSchema有关的超慢查询，想问下是什么原因

%E8%B6%85%E6%85%A2sql
%E8%B6%85%E6%85%A2sql2292×952 273 KB

2

此类语句 应该与使用 dashboard 有关. 属于 TiDB 的内部语句.
可以通过 数据库选择 过滤不感兴趣的 数据库

image
image3132×1144 270 KB

3

你好，这些 SQL 是 dashboard 向 TiDB 发送的 SQL，正常应该很快执行完的。能否点进去看下详细的执行时间，截图发一下？
另外，这些 SQL 会影响 “SQL 语句分析” 的使用，您目前使用是否正常？

4

目前还是正常的，我个sql和对应的执行计划啊
SQL：
SELECT
DISTINCT FLOOR(UNIX_TIMESTAMP(summary_begin_time)) AS begin_time,
FLOOR(UNIX_TIMESTAMP(summary_end_time)) AS end_time
FROM
INFORMATION_SCHEMA.CLUSTER_STATEMENTS_SUMMARY_HISTORY
ORDER BY
summary_begin_time DESC,
summary_end_time DESC;

计划：
id task estRows operator info actRows execution info memory disk
Projection_6 root 8000 Column#73, Column#74 7 time:31m19.987430378s, loops:2, Concurrency:4 25.21875 KB N/A
└─Sort_7 root 8000 information_schema.cluster_statements_summary_history.summary_begin_time:desc, information_schema.cluster_statements_summary_history.summary_end_time:desc 7 time:31m19.987363062s, loops:2 14.0625 KB 0 Bytes
└─HashAgg_11 root 8000 group by:Column#73, Column#74, funcs:firstrow(Column#73)->Column#73, funcs:firstrow(Column#74)->Column#74, funcs:firstrow(information_schema.cluster_statements_summary_history.summary_begin_time)->information_schema.cluster_statements_summary_history.summary_begin_time, funcs:firstrow(information_schema.cluster_statements_summary_history.summary_end_time)->information_schema.cluster_statements_summary_history.summary_end_time 7 time:31m19.987294632s, loops:5, PartialConcurrency:4, FinalConcurrency:4 66.54296875 KB N/A
└─Projection_12 root 10000 floor(unix_timestamp(information_schema.cluster_statements_summary_history.summary_begin_time))->Column#73, floor(unix_timestamp(information_schema.cluster_statements_summary_history.summary_end_time))->Column#74, information_schema.cluster_statements_summary_history.summary_begin_time, information_schema.cluster_statements_summary_history.summary_end_time 425 time:31m19.986742288s, loops:2, Concurrency:4 54.66015625 KB N/A
└─TableReader_14 root 10000 data:TableFullScan_13 425 time:31m19.986472191s, loops:2 6.810546875 KB N/A
└─TableScan_13 cop 10000 table:CLUSTER_STATEMENTS_SUMMARY_HISTORY, keep order:false, stats:pseudo -1 time:0s, loops:0 N/A N/A

5

看这个执行计划耗时31分钟？方便发一下问题发生时的监控信息吗？over-view. tidb. detail-tikv