Invalid Ticdc parameter partition-num for Tidb7.1.1

[cloudWang001]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

1. Create a Kafka topic with 3 partitions
2. Create Ticdc changefeed:
   curl -X POST http://xxx.xxx.xxx.xxx:8300/api/v2/changefeeds -d ‘{“changefeed_id”:“test-patition”,“start_ts”: 445150430914150401,“sink_uri”:“kafka://XXX.XXX.XXX.XXX:9092/kafka-task1?enable-tidb-extension=true&partition-num=1&replication-factor=1&max-message-bytes=67108864”,“replica_config”: {“filter”: {“rules”:[“test_cdc."]},“ignore_ineligible_table”: true,“mounter”: {“worker_num”: 16},“sink”: {“dispatchers”: [{“matcher”: ["test_cdc.”],“partition”: “index-value”}],“protocol”: “canal-json”}}}’

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

Kafka only has one partition with synchronized data, and the other two partitions should not have synchronized data.

3. What did you see instead (Required)

All three partitions of Kafka have synchronized data.

4. What is your TiDB version? (Required)

Release Version: v7.1.1
Edition: Community
Git Commit Hash: cf441574864be63938524e7dfcf7cc659edc3dd8
Git Branch: heads/refs/tags/v7.1.1
UTC Build Time: 2023-07-19 10:20:53
GoVersion: go1.20.6
Race Enabled: false
TiKV Min Version: 6.2.0-alpha
Check Table Before Drop: false
Store: tikv

5. PS

1.The parameter replication-factor=1 or 3 does not affect the results.

2.The results obtained by using API v2 or the command line cdc cli changefeed create are the same.

3.The parameter partition-num is valid in Tidb4.0.15, but it becomes invalid in Tidb7.1.1：
Tidb7.1.1:
(1) partition-num=3, topic partitions=3 : 3 partitions have synchronized data
(2) partition-num=2, topic partitions=3 : 3 partitions have synchronized data
(3) partition-num=1, topic partitions=3 : 3 partitions have synchronized data

(4) partition-num=2, topic partitions=2 : 2 partitions have synchronized data
(5) partition-num=1, topic partitions=2 : 2 partitions have synchronized data

Tidb4.0.15:
(1) partition-num=3, topic partitions=3 : 3 partitions have synchronized data
(2) partition-num=2, topic partitions=3 : 2 partitions have synchronized data
(3) partition-num=1, topic partitions=3 : 1 partitions have synchronized data

(4) partition-num=2, topic partitions=2 : 2 partitions have synchronized data
(5) partition-num=1, topic partitions=2 : 1 partitions have synchronized data

[fubinzh]

/severity major

[fubinzh]

CDC had below WARN log printed, however all partitions have messages dispatched.

["number of partition specified in sink-uri is less than that of the actual topic. Some partitions will not have messages dispatched to"] [sinkUriPartitions=1] [topicPartitions=3]

[seiya-annie]

/found community