Failed to Synchronize Data Field Changes with DM in TiDB Version 4.0.7

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This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: TiDB 4.0.7版本的DM同步数据改动字段失败

| username: 晓峰008

[TiDB Usage Environment] Production Environment
[TiDB Version] tidb v4.0.7, dm v2.0.3
[Reproduction Path] When altering the table structure in the MySQL business system, changing the varchar type field from large to small causes synchronization failure.
[Problem Phenomenon and Impact]

  1. Problem: Changing the field length from long to short in the upstream table causes DM synchronization failure.
  2. Impact: Synchronization gets stuck, requiring manual adjustment of the field to consume data normally.
    [Attachments: Screenshots/Logs/Monitoring]
    image
    image1380×134 54 KB

    [Actions Taken]
  3. SET GLOBAL tidb_enable_change_column_type=1; – Not effective, prompt: Unknown system variable ‘tidb_enable_change_column_type’
  4. select @@tidb_enable_change_column_type; – Not effective, prompt: Unknown system variable ‘tidb_enable_change_column_type’
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| username: xfworld | Original post link

Lossy modifications are not supported.

To solve this problem, you can only skip it.

image
image1039×198 9.54 KB

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| username: 晓峰008 | Original post link

Sure, thanks♪(･ω･)ﾉ. How do I configure the parameter tidb_enable_change_column_type in version 4.0.7? I didn’t see this attribute in the global variables.

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| username: xfworld | Original post link

According to the image above, 4.X is not supported.

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| username: 晓峰008 | Original post link

Okay :+1:

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| username: system | Original post link

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