[kv:8025] Entry too large, the maximum entry size is 6291456, the size of data is 7890542

Translated
1

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

Original topic: [kv:8025]entry too large, the max entry size is 6291456, the size of data is 7890542

| username: Haaahei

[TiDB Version]
TiDB v6.1.0
DM v6.1.0

[Problem Encountered]
An error occurred during DM synchronization where a single key exceeded the maximum limit, as follows:

“errors”: [
{
“ErrCode”: 50000,
“ErrClass”: “not-set”,
“ErrScope”: “not-set”,
“ErrLevel”: “high”,
“Message”: “[kv:8025]entry too large, the max entry size is 6291456, the size of data is 7890542”,
“RawCause”: “”,
“Workaround”: “”
}
],

To check if it is indeed a TiDB issue, a large field was generated and inserted into TiDB:

[2022/07/04 09:15:22.423 +08:00] [INFO] [2pc.go:629] [“[BIG_TXN]”] [session=6284447824554729039] [“key sample”=748000000000000ad95f728000000000000003] [size=37119529] [keys=1] [puts=1] [dels=0] [locks=0] [checks=0] [txnStartTS=434345691549007898]

The insertion into the database was successful, and the data was also retrievable. The relevant TiDB parameters are as follows:

+------+---------------------+--------------------------------------+-----------+
| Type | Instance            | Name                                 | Value     |
+------+---------------------+--------------------------------------+-----------+
| tidb | xxxxx:4000     | performance.txn-entry-size-limit     | 125829120 |
| tikv | xxxxx:20161 | raftstore.raft-entry-max-size        | 128MiB    |
+------+---------------------+--------------------------------------+-----------+

A bug has been reported: the 'txn-entry-size-limit' config is not effective in DM · Issue #6161 · pingcap/tiflow · GitHub

2
| username: Haaahei | Original post link

After downgrading the DM version to v5.4.1, synchronization returned to normal.

3
| username: guominghao | Original post link

Are there many tables being synchronized?

4
| username: Haaahei | Original post link

More than 500 tables; suspect that DM6.1 internally imposed a txn-entry-size-limit restriction and returned directly, without reaching TiDB execution.

5
| username: guominghao | Original post link

The error is a TiDB error. Can you confirm that the transactions executed upstream do not exceed TiDB’s limits?

6
| username: Haaahei | Original post link

I have already set the TiDB limit to 120MB, and the synchronized data is only over 7MB, which does not exceed the limit. After downgrading to 5.4.1, the synchronization works normally.

7
| username: guominghao | Original post link

I have confirmed that it is a limitation within DM, and it will be fixed later.

8
| username: Haaahei | Original post link

Okay, it feels like version 6.1 is not very stable, there have already been several issues :thinking:

9
| username: lance6716 | Original post link

Thank you for the feedback. You can check the progress of the fix at the 'txn-entry-size-limit' config is not effective in DM · Issue #6161 · pingcap/tiflow · GitHub.

10
| username: system | Original post link

This topic was automatically closed 1 minute after the last reply. No new replies are allowed.