JNSimba commented on code in PR #3415:
URL: https://github.com/apache/flink-cdc/pull/3415#discussion_r1778269742
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flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/debezium/task/MySqlSnapshotSplitReadTask.java:
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@@ -187,6 +192,9 @@ protected SnapshotResult<MySqlOffsetContext> doExecute(
} else {
// Get the current binlog offset as HW
highWatermark = DebeziumUtils.currentBinlogOffset(jdbcConnection);
+ long epochSecond = clock.currentTime().getEpochSecond();
+ highWatermark.getOffset().put(BinlogOffset.TIMESTAMP_KEY,
String.valueOf(epochSecond));
+ highWatermark.getOffset().put(BinlogOffset.SERVER_ID_KEY,
String.valueOf(epochSecond));
Review Comment:
In the [configureFilter
method](https://github.com/apache/flink-cdc/blob/master/flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/debezium/reader/BinlogSplitReader.java#L289-L302)
of BinlogSplitReader In the process, the highWatermark of all chunks will be
compared to obtain the largest one.
When the table has multiple chunks
chunk-1:timestamp=1727423957,binlogpostion=1001
chunk-2:timestamp=1727423958,binlogpostion=1002
chunk-3:timestamp=1727423959,binlogpostion=1002
chunk-4:timestamp=1727423960,binlogpostion=1002
However, at this time, the serverid is 0, but the BinlogPosition may be
different (because new data has been added during the period). According to the
current logic of **BinlogOffset.compare**: if the serverid is the same, the
postion/filename will be compared. However, for chunk-2/chunk-3/chunk-4, except
for the timestamp, everything else is the same, so the calculated highWatermark
is finally chunk-2, which will lead to duplicate data.
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