Severe Bug in TiFlash

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Original topic: tiflash严重bug

| username: 华健-梦诚科技

Severe bug in streamAgg, see the image below:


| username: Billmay表妹 | Original post link

Can you briefly describe what the bug is? I don’t quite understand and need a summary of the issue in text form. Could you provide that?

| username: flow-PingCAP | Original post link

Hello, could you please try the following:

  1. What is the result if this erroneous SQL is forced to run on TiKV?
  2. Run SELECT COUNT(*) using TiFlash and TiKV respectively.

Also, could you please provide the TiDB version number?

| username: 华健-梦诚科技 | Original post link

The version number selected in the question is 6.1.1.

Forcing to use TiKV and forcing to use MPP both yield the correct results.

The count is the same.

| username: windtalker | Original post link

This is indeed a bug. When streaming agg is used with group by, it is pushed down to TiFlash. Actually, MPP does not guarantee the correctness of the result, but in your plan, the final agg stage is also executed in MPP, so the result is correct.

This bug should be fixed in versions 6.1.4 and 6.5. It is recommended to upgrade to avoid this issue. Otherwise, the only way to completely avoid this problem is to force not reading from TiFlash.

| username: 华健-梦诚科技 | Original post link

Got it, I’ll upgrade it then. Thanks.

| username: system | Original post link

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