[FLINK-38691] [cdc connector mysql] Support for MySQL Transaction Boundary Events in Flink CDC Connector (apache#4170)

Author: tejanshrana

flink-cdc-connect/flink-cdc-pipeline-connectors/flink-cdc-pipeline-connector-mysql/src/main/java/org/apache/flink/cdc/connectors/mysql/source/reader/MySqlPipelineRecordEmitter.java

@@ -93,7 +93,8 @@ public MySqlPipelineRecordEmitter(
                 debeziumDeserializationSchema,
                 sourceReaderMetrics,
                 sourceConfig.isIncludeSchemaChanges(),
-                false); // Explicitly disable heartbeat events
+                false, // Explicitly disable heartbeat events
+                false); // Explicitly disable transaction metadata events
         this.debeziumDeserializationSchema = debeziumDeserializationSchema;
         this.sourceConfig = sourceConfig;
         this.alreadySendCreateTableTables = new HashSet<>();

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/MySqlSource.java

@@ -133,7 +133,8 @@ public static <T> MySqlSourceBuilder<T> builder() {
                                 deserializationSchema,
                                 sourceReaderMetrics,
                                 sourceConfig.isIncludeSchemaChanges(),
-                                sourceConfig.isIncludeHeartbeatEvents()));
+                                sourceConfig.isIncludeHeartbeatEvents(),
+                                sourceConfig.isIncludeTransactionMetadataEvents()));
     }
 
     MySqlSource(

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/MySqlSourceBuilder.java

@@ -198,6 +198,13 @@ public MySqlSourceBuilder<T> includeSchemaChanges(boolean includeSchemaChanges)
         return this;
     }
 
+    /** Whether the {@link MySqlSource} should output the transaction metadata events or not. */
+    public MySqlSourceBuilder<T> includeTransactionMetadataEvents(
+            boolean includeTransactionMetadataEvents) {
+        this.configFactory.includeTransactionMetadataEvents(includeTransactionMetadataEvents);
+        return this;
+    }
+
     /** Whether the {@link MySqlSource} should scan the newly added tables or not. */
     public MySqlSourceBuilder<T> scanNewlyAddedTableEnabled(boolean scanNewlyAddedTableEnabled) {
         this.configFactory.scanNewlyAddedTableEnabled(scanNewlyAddedTableEnabled);

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/config/MySqlSourceConfig.java

@@ -63,6 +63,7 @@ public class MySqlSourceConfig implements Serializable {
     private final double distributionFactorLower;
     private final boolean includeSchemaChanges;
     private final boolean includeHeartbeatEvents;
+    private final boolean includeTransactionMetadataEvents;
     private final boolean scanNewlyAddedTableEnabled;
     private final boolean closeIdleReaders;
     private final Properties jdbcProperties;
@@ -101,6 +102,7 @@ public class MySqlSourceConfig implements Serializable {
             double distributionFactorLower,
             boolean includeSchemaChanges,
             boolean includeHeartbeatEvents,
+            boolean includeTransactionMetadataEvents,
             boolean scanNewlyAddedTableEnabled,
             boolean closeIdleReaders,
             Properties dbzProperties,
@@ -131,6 +133,7 @@ public class MySqlSourceConfig implements Serializable {
         this.distributionFactorLower = distributionFactorLower;
         this.includeSchemaChanges = includeSchemaChanges;
         this.includeHeartbeatEvents = includeHeartbeatEvents;
+        this.includeTransactionMetadataEvents = includeTransactionMetadataEvents;
         this.scanNewlyAddedTableEnabled = scanNewlyAddedTableEnabled;
         this.closeIdleReaders = closeIdleReaders;
         this.dbzProperties = checkNotNull(dbzProperties);
@@ -234,6 +237,10 @@ public boolean isIncludeHeartbeatEvents() {
         return includeHeartbeatEvents;
     }
 
+    public boolean isIncludeTransactionMetadataEvents() {
+        return includeTransactionMetadataEvents;
+    }
+
     public boolean isScanNewlyAddedTableEnabled() {
         return scanNewlyAddedTableEnabled;
     }

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/config/MySqlSourceConfigFactory.java

@@ -23,6 +23,8 @@
 import org.apache.flink.cdc.connectors.mysql.table.StartupOptions;
 import org.apache.flink.table.catalog.ObjectPath;
 
+import io.debezium.config.CommonConnectorConfig;
+
 import java.io.Serializable;
 import java.time.Duration;
 import java.time.ZoneId;
@@ -64,6 +66,7 @@ public class MySqlSourceConfigFactory implements Serializable {
             MySqlSourceOptions.CHUNK_KEY_EVEN_DISTRIBUTION_FACTOR_LOWER_BOUND.defaultValue();
     private boolean includeSchemaChanges = false;
     private boolean includeHeartbeatEvents = false;
+    private boolean includeTransactionMetadataEvents = false;
     private boolean scanNewlyAddedTableEnabled = false;
     private boolean closeIdleReaders = false;
     private Properties jdbcProperties;
@@ -242,6 +245,13 @@ public MySqlSourceConfigFactory includeHeartbeatEvents(boolean includeHeartbeatE
         return this;
     }
 
+    /** Whether the {@link MySqlSource} should output the transaction metadata events or not. */
+    public MySqlSourceConfigFactory includeTransactionMetadataEvents(
+            boolean includeTransactionMetadataEvents) {
+        this.includeTransactionMetadataEvents = includeTransactionMetadataEvents;
+        return this;
+    }
+
     /** Whether the {@link MySqlSource} should scan the newly added tables or not. */
     public MySqlSourceConfigFactory scanNewlyAddedTableEnabled(boolean scanNewlyAddedTableEnabled) {
         this.scanNewlyAddedTableEnabled = scanNewlyAddedTableEnabled;
@@ -366,6 +376,10 @@ public MySqlSourceConfig createConfig(int subtaskId, String serverName) {
         // Note: the includeSchemaChanges parameter is used to control emitting the schema record,
         // only DataStream API program need to emit the schema record, the Table API need not
         props.setProperty("include.schema.changes", String.valueOf(true));
+        // enable transaction metadata if includeTransactionMetadataEvents is true
+        props.setProperty(
+                CommonConnectorConfig.PROVIDE_TRANSACTION_METADATA.name(),
+                String.valueOf(includeTransactionMetadataEvents));
         // disable the offset flush totally
         props.setProperty("offset.flush.interval.ms", String.valueOf(Long.MAX_VALUE));
         // disable tombstones
@@ -420,6 +434,7 @@ public MySqlSourceConfig createConfig(int subtaskId, String serverName) {
                 distributionFactorLower,
                 includeSchemaChanges,
                 includeHeartbeatEvents,
+                includeTransactionMetadataEvents,
                 scanNewlyAddedTableEnabled,
                 closeIdleReaders,
                 props,

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/reader/MySqlRecordEmitter.java

@@ -54,17 +54,20 @@ public class MySqlRecordEmitter<T> implements RecordEmitter<SourceRecords, T, My
     private final MySqlSourceReaderMetrics sourceReaderMetrics;
     private final boolean includeSchemaChanges;
     private final boolean includeHeartbeatEvents;
+    private final boolean includeTransactionMetadataEvents;
     private final OutputCollector<T> outputCollector;
 
     public MySqlRecordEmitter(
             DebeziumDeserializationSchema<T> debeziumDeserializationSchema,
             MySqlSourceReaderMetrics sourceReaderMetrics,
             boolean includeSchemaChanges,
-            boolean includeHeartbeatEvents) {
+            boolean includeHeartbeatEvents,
+            boolean includeTransactionMetadataEvents) {
         this.debeziumDeserializationSchema = debeziumDeserializationSchema;
         this.sourceReaderMetrics = sourceReaderMetrics;
         this.includeSchemaChanges = includeSchemaChanges;
         this.includeHeartbeatEvents = includeHeartbeatEvents;
+        this.includeTransactionMetadataEvents = includeTransactionMetadataEvents;
         this.outputCollector = new OutputCollector<>();
     }
 
@@ -108,6 +111,11 @@ protected void processElement(
             if (includeHeartbeatEvents) {
                 emitElement(element, output);
             }
+        } else if (RecordUtils.isTransactionMetadataEvent(element)) {
+            updateStartingOffsetForSplit(splitState, element);
+            if (includeTransactionMetadataEvents) {
+                emitElement(element, output);
+            }
         } else {
             // unknown element
             LOG.info("Meet unknown element {}, just skip.", element);

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/source/utils/RecordUtils.java

@@ -73,6 +73,8 @@ private RecordUtils() {}
             "io.debezium.connector.mysql.SchemaChangeKey";
     public static final String SCHEMA_HEARTBEAT_EVENT_KEY_NAME =
             "io.debezium.connector.common.Heartbeat";
+    public static final String SCHEMA_TRANSACTION_METADATA_EVENT_KEY_NAME =
+            "io.debezium.connector.common.TransactionMetadataKey";
     private static final DocumentReader DOCUMENT_READER = DocumentReader.defaultReader();
 
     /** Converts a {@link ResultSet} row to an array of Objects. */
@@ -339,6 +341,18 @@ public static boolean isHeartbeatEvent(SourceRecord record) {
                 && SCHEMA_HEARTBEAT_EVENT_KEY_NAME.equalsIgnoreCase(valueSchema.name());
     }
 
+    /**
+     * Check whether the given source record is a transaction metadata event (BEGIN or END).
+     *
+     * <p>Transaction events are emitted by Debezium to mark transaction boundaries when
+     * provide.transaction.metadata is enabled.
+     */
+    public static boolean isTransactionMetadataEvent(SourceRecord record) {
+        Schema keySchema = record.keySchema();
+        return keySchema != null
+                && SCHEMA_TRANSACTION_METADATA_EVENT_KEY_NAME.equalsIgnoreCase(keySchema.name());
+    }
+
     /**
      * Return the finished snapshot split information.
      *