mysql-test(filesort_merge) failed.

[wjhuang2016]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

https://ci.pingcap.net/blue/organizations/jenkins/tidb_ghpr_integration_common_test/detail/tidb_ghpr_integration_common_test/12349/pipeline

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

master

[Yisaer]

[2022/08/10 14:07:17.734 +08:00] [INFO] [handle.go:1189] ["[stats] directly update count"] [tableID=91] [results.Count=2373] [count=2373]
[2022/08/10 14:07:18.005 +08:00] [INFO] [analyze.go:426] ["analyze table `filesort_merge`.`t1` has finished"] [partition=] ["job info"="analyze table all columns with 256 buckets, 500 topn, 1 samplerate"] ["start time"=2022/08/10 14:07:17.715 +08:00] ["end time"=2022/08/10 14:07:17.980 +08:00] [cost=265.736394ms]
[2022/08/10 14:07:22.272 +08:00] [INFO] [manager.go:296] ["get owner"] ["owner info"="[log-backup] /tidb/br-stream/owner ownerManager e451b3b2-6623-4ab7-b4ae-754a5e9c9aa8"] [ownerID=e451b3b2-6623-4ab7-b4ae-754a5e9c9aa8]
[2022/08/10 14:07:26.845 +08:00] [INFO] [data_window.go:248] ["Error exists when getting the SQL Metric."]
[2022/08/10 14:07:32.551 +08:00] [INFO] [update.go:1133] ["[stats] auto analyze triggered"] [sql="analyze table `filesort_merge`.`t1`"] [reason="too many modifications(3072/2373>0.5)"]

From log we can find that 2373 is directly returned by analyze response Count from TiKV. A possibility root cause is about to txn isolation level.

The default isolation level is RC as following: https://github.com/pingcap/tidb/blob/8e77ce264c7286fd592709d8e625459fd04a7351/distsql/request_builder.go#L160-L171

and the testcase failed about 5 or 6 times once. After I changed it into SI, the testcase success 20 times in a row on my local env.

[Yisaer]

As the tikv analyze response returned wrong value, I transfer this issue into https://github.com/tikv/tikv/issues/13258

[Yisaer]

I will close this issue as it seems we won't see this error in mysql-test now. Further information will be tracked in https://github.com/tikv/tikv/issues/13258