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[FLINK-38846][mysql] Optimize LinkedList processing in handleChange method to reduce complexity #4250

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Merged
lvyanquan merged 2 commits into from
Feb 3, 2026
+30 −10
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[FLINK-38846][mysql] Optimize LinkedList processing in handleChange method to reduce complexity #4250

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8be7d44
[FLINK-38846][mysql] Optimize LinkedList processing in handleChange m…
Hisoka-X Jan 31, 2026
25b61da
[FLINK-38846][mysql] Optimize LinkedList processing in handleChange m…
Hisoka-X Jan 31, 2026
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20 changes: 15 additions & 5 deletions ...-mysql-cdc/src/main/java/io/debezium/connector/mysql/MySqlStreamingChangeEventSource.java
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Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,9 @@
* specifying starting offset on start.
*
* <p>Line 1485 : Add more error details for some exceptions.
*
* <p>Line 947-958 : Use iterator instead of index-based loop to avoid O(n²) complexity when
* processing LinkedList rows in handleChange method. See FLINK-38846.
*/
public class MySqlStreamingChangeEventSource
implements StreamingChangeEventSource<MySqlPartition, MySqlOffsetContext> {
Expand Down Expand Up @@ -941,11 +944,18 @@ private <T extends EventData, U> void handleChange(
int count = 0;
int numRows = rows.size();
if (startingRowNumber < numRows) {
for (int row = startingRowNumber; row != numRows; ++row) {
offsetContext.setRowNumber(row, numRows);
offsetContext.event(tableId, eventTimestamp);
changeEmitter.emit(tableId, rows.get(row));
count++;
// Use iterator to avoid O(n²) complexity when rows is a LinkedList
// (mysql-binlog-connector-java uses LinkedList in WriteRowsEventDataDeserializer
// and DeleteRowsEventDataDeserializer)
int rowIndex = 0;
for (U rowData : rows) {
if (rowIndex >= startingRowNumber) {
offsetContext.setRowNumber(rowIndex, numRows);
offsetContext.event(tableId, eventTimestamp);
changeEmitter.emit(tableId, rowData);
count++;
}
rowIndex++;
}
if (LOGGER.isDebugEnabled()) {
if (startingRowNumber != 0) {
Expand Down
20 changes: 15 additions & 5 deletions ...anbase-cdc/src/main/java/io/debezium/connector/mysql/MySqlStreamingChangeEventSource.java
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Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,9 @@
* specifying starting offset on start.
*
* <p>Line 1485 : Add more error details for some exceptions.
*
* <p>Line 951-964 : Use iterator instead of index-based loop to avoid O(n²) complexity when
* processing LinkedList rows in handleChange method. See FLINK-38846.
*/
public class MySqlStreamingChangeEventSource
implements StreamingChangeEventSource<MySqlPartition, MySqlOffsetContext> {
Expand Down Expand Up @@ -946,11 +949,18 @@ private <T extends EventData, U> void handleChange(
int count = 0;
int numRows = rows.size();
if (startingRowNumber < numRows) {
for (int row = startingRowNumber; row != numRows; ++row) {
offsetContext.setRowNumber(row, numRows);
offsetContext.event(tableId, eventTimestamp);
changeEmitter.emit(tableId, rows.get(row));
count++;
// Use iterator to avoid O(n²) complexity when rows is a LinkedList
// (mysql-binlog-connector-java uses LinkedList in WriteRowsEventDataDeserializer
// and DeleteRowsEventDataDeserializer)
int rowIndex = 0;
for (U rowData : rows) {
if (rowIndex >= startingRowNumber) {
offsetContext.setRowNumber(rowIndex, numRows);
offsetContext.event(tableId, eventTimestamp);
changeEmitter.emit(tableId, rowData);
count++;
}
rowIndex++;
}
if (LOGGER.isDebugEnabled()) {
if (startingRowNumber != 0) {
Expand Down
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