the events are dispatched to different partitions unexpectedly

[zier-one]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do? If possible, provide a recipe for reproducing the error.

There is a table in upstream TiDB:

CREATE TABLE `mars_task_verify_statistics` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `resource_id` varchar(24) NOT NULL,
  `task_id` bigint(20) NOT NULL,
  `source` varchar(36) NOT NULL,
  `category` varchar(26) DEFAULT NULL,
  `priority` smallint(6) DEFAULT 0,
  `type` smallint(6) NOT NULL,
  `task_time` timestamp NOT NULL,
  `start_time` timestamp NULL DEFAULT NULL,
  `end_time` timestamp NULL DEFAULT NULL,
  `reason` varchar(256) DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `idx_resource_id` (`resource_id`),
  UNIQUE KEY `u_source_task` (`source`,`task_id`),
  KEY `idx_task_time` (`task_time`),
  KEY `idx_end_time` (`end_time`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin

the dispatcher of this table is rowid, we received the following message from Kafka:

[Thread-0][partition-0]
Total Bytes: 159
[CanalEntry]:
header {
  version: 1
  serverenCode: "UTF-8"
  executeTime: 1593749327652
  sourceType: MYSQL
  schemaName: "mars"
  tableName: "mars_task_verify_statistics"
  eventType: DELETE
  props {
    key: "rowsCount"
    value: "1"
  }
}
entryType: ROWDATA
storeValue: "\020\003P\000bB\n$\020\f\032\006source \0010\000B\024user_info_after_pass\n\032\020\003\032\atask_id \0010\000B\t229209952"

[RowChange]:
eventType: DELETE
isDdl: false
rowDatas {
  beforeColumns {
    sqlType: 12
    name: "source"
    isKey: true
    isNull: false
    value: "user_info_after_pass"
  }
  beforeColumns {
    sqlType: 3
    name: "task_id"
    isKey: true
    isNull: false
    value: "229209952"
  }
}

[Thread-0][partition-28]
Total Bytes: 113
[CanalEntry]:
header {
  version: 1
  serverenCode: "UTF-8"
  executeTime: 1593749327652
  sourceType: MYSQL
  schemaName: "mars"
  tableName: "mars_task_verify_statistics"
  eventType: DELETE
  props {
    key: "rowsCount"
    value: "1"
  }
}
entryType: ROWDATA
storeValue: "\020\003P\000b\026\n\024\020\003\032\002id \0010\000B\b22647228"

[RowChange]:
eventType: DELETE
isDdl: false
rowDatas {
  beforeColumns {
    sqlType: 3
    name: "id"
    isKey: true
    isNull: false
    value: "22647228"
  }
}

we can found that the delete events of one row are dispatched to different partitions, it's not expected

4. Versions of the cluster

v4.0.2