TiCDC Error: A Single Changefeed Exceeds ETCD Transaction Max Size: 1310720

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

Original topic: ticdc 报错 a single changefeed exceed etcd txn max size:1310720

| username: foxchan

[TiDB Usage Environment] Production Environment
[TiDB Version] v5.4.2
[Encountered Problem: Problem Phenomenon and Impact]
CDC synchronization fails to start after an abnormal restart.
The error indicates that the txn size is too large.

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| username: xfworld | Original post link

After version 6.1, CDC supports transaction splitting.

Currently, the version can only split transactions at the service level to reduce transaction size.

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| username: foxchan | Original post link

Can I use CDC 6.1 to run on a TiDB 5.4 cluster?

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| username: xfworld | Original post link

No, the versions of TiDB components should ideally be consistent…

Moreover, 5.X and 6.X have a major version difference, which is likely to be incompatible…

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| username: foxchan | Original post link

Alright, I’ll use BR then, since the business can’t be changed immediately. Thanks for the reply.

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| username: asddongmen | Original post link

Hello, this error means that the metadata information contained in a changefeed has exceeded the size that a single etcd transaction can handle. This issue is likely caused by a changefeed synchronizing too many tables. How many tables are you synchronizing with a single changefeed?

If you are not willing to upgrade the CDC version, the possible solutions are as follows:

  1. Record the current checkpointTs of the changefeed.
  2. Stop the GC of the upstream TiDB cluster.
  3. Delete the metadata of the changefeed in etcd.
  4. Start a new synchronization task, set the startTs to the recorded checkpointTs, and ensure that each changefeed does not synchronize more than 500 tables.

This issue has been resolved in version 6.0.0 and later. You might consider using CDC version 6.1.2 for synchronization. According to current test results, CDC 6.1.2 is compatible with TiDB 5.4.2.

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| username: foxchan | Original post link

1969 tables, 1 changefeed
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I have already deleted the etcd metadata and resynchronized.
PS: If CDC has a txn exception, it will restart in a loop. You can only manage it by operating etcd. I hope the official team provides some command instructions for easier management.

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| username: h5n1 | Original post link

Is there any documentation that explains which versions of CDC are backward compatible with which versions of TiKV? Can 6.1.2 CDC be compatible with 5.2.3?

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| username: system | Original post link

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