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[FLINK-37191][mysql] Avoid back filling if the lowWatermark of BinlogSplit is equal to highWatermark. #3902

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merged 4 commits into from
Feb 11, 2025
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[FLINK-37191][mysql] Avoid back filling if the lowWatermark of BinlogSplit is equal to highWatermark. #3902

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e26a99f
Revert "[FLINK-35600][pipeline-connector/mysql] Add timestamp for low…
lvyanquan Feb 7, 2025
5e57e72
[FLINK-35600][pipeline-connector/mysql] Skip the record that is equal…
lvyanquan Feb 7, 2025
27e3360
[FLINK-35600][pipeline-connector/mysql] Skip the record that is equal…
lvyanquan Feb 9, 2025
8e45c31
Optimize logic.
lvyanquan Feb 11, 2025
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2 changes: 1 addition & 1 deletion ...rc/main/java/org/apache/flink/cdc/connectors/mysql/debezium/reader/BinlogSplitReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -292,7 +292,7 @@ private boolean shouldEmit(SourceRecord sourceRecord) {
private boolean hasEnterPureBinlogPhase(TableId tableId, BinlogOffset position) {
// the existed tables those have finished snapshot reading
if (maxSplitHighWatermarkMap.containsKey(tableId)
&& position.isAtOrAfter(maxSplitHighWatermarkMap.get(tableId))) {
&& position.isAfter(maxSplitHighWatermarkMap.get(tableId))) {
pureBinlogPhaseTables.add(tableId);
return true;
}
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10 changes: 0 additions & 10 deletions .../java/org/apache/flink/cdc/connectors/mysql/debezium/task/MySqlSnapshotSplitReadTask.java
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Original file line number Diff line number Diff line change
Expand Up @@ -154,11 +154,6 @@ protected SnapshotResult<MySqlOffsetContext> doExecute(
hooks.getPreLowWatermarkAction().accept(jdbcConnection, snapshotSplit);
}
final BinlogOffset lowWatermark = DebeziumUtils.currentBinlogOffset(jdbcConnection);
lowWatermark
.getOffset()
.put(
BinlogOffset.TIMESTAMP_KEY,
String.valueOf(clock.currentTime().getEpochSecond()));
LOG.info(
"Snapshot step 1 - Determining low watermark {} for split {}",
lowWatermark,
Expand Down Expand Up @@ -192,11 +187,6 @@ protected SnapshotResult<MySqlOffsetContext> doExecute(
} else {
// Get the current binlog offset as HW
highWatermark = DebeziumUtils.currentBinlogOffset(jdbcConnection);
highWatermark
.getOffset()
.put(
BinlogOffset.TIMESTAMP_KEY,
String.valueOf(clock.currentTime().getEpochSecond()));
}

LOG.info(
Expand Down
11 changes: 4 additions & 7 deletions ...l-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/offset/BinlogOffset.java
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@yuxiqian yuxiqian Feb 6, 2025 •
edited
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BinlogOffset#compareTo is a general-purposed comparison method, and this change might affect more than backfill necessity check. Is it possible to tweak SnapshotSplitReader#isBackfillRequired only?

Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,9 @@ public int compareTo(BinlogOffset that) {
// compared ...
long timestamp = this.getTimestampSec();
long targetTimestamp = that.getTimestampSec();
return Long.compare(timestamp, targetTimestamp);
if (timestamp != 0 && targetTimestamp != 0) {
return Long.compare(timestamp, targetTimestamp);
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This change is necessary because that if the TimestampSec is 0, the assumption of These are from different servers, and their binlog coordinates are not related is not correct, these two BinlogOffsets could come from the same server.

}
}

// First compare the MySQL binlog filenames
Expand All @@ -251,12 +253,7 @@ public int compareTo(BinlogOffset that) {
}

// The completed events are the same, so compare the row number ...
if (this.getRestartSkipRows() != that.getRestartSkipRows()) {
return Long.compare(this.getRestartSkipRows(), that.getRestartSkipRows());
}

// The skip rows are the same, so compare the timestamp ...
return Long.compare(this.getTimestampSec(), that.getTimestampSec());
return Long.compare(this.getRestartSkipRows(), that.getRestartSkipRows());
}

public boolean isAtOrBefore(BinlogOffset that) {
Expand Down
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