[FLINK-36945] MySQL CDC supports parsing RENAME TABLE Statement with multiple tables

flink-cdc-connect/flink-cdc-source-connectors/flink-connector-mysql-cdc/src/main/java/org/apache/flink/cdc/connectors/mysql/debezium/dispatcher/EventDispatcherImpl.java

@@ -29,7 +29,9 @@
 import io.debezium.pipeline.source.spi.EventMetadataProvider;
 import io.debezium.pipeline.spi.ChangeEventCreator;
 import io.debezium.pipeline.spi.SchemaChangeEventEmitter;
+import io.debezium.relational.TableId;
 import io.debezium.relational.history.HistoryRecord;
+import io.debezium.relational.history.TableChanges;
 import io.debezium.schema.DataCollectionFilters;
 import io.debezium.schema.DataCollectionId;
 import io.debezium.schema.DatabaseSchema;
@@ -45,10 +47,14 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
+import static io.debezium.connector.AbstractSourceInfo.TABLE_NAME_KEY;
 import static org.apache.flink.cdc.connectors.mysql.debezium.dispatcher.SignalEventDispatcher.BINLOG_FILENAME_OFFSET_KEY;
 import static org.apache.flink.cdc.connectors.mysql.debezium.dispatcher.SignalEventDispatcher.BINLOG_POSITION_OFFSET_KEY;
 
@@ -206,11 +212,103 @@ private Struct schemaChangeRecordValue(SchemaChangeEvent event) throws IOExcepti
             String historyStr = DOCUMENT_WRITER.write(historyRecord.document());
 
             Struct value = new Struct(schemaChangeValueSchema);
-            value.put(HistoryRecord.Fields.SOURCE, event.getSource());
+            value.put(HistoryRecord.Fields.SOURCE, rewriteTableNameIfNeeded(event));
             value.put(HISTORY_RECORD_FIELD, historyStr);
             return value;
         }
 
+        /**
+         * Rewrites the table name in the Source if needed to handle schema changes properly.
+         *
+         * <p>This method addresses a specific issue when renaming multiple tables within a single
+         * statement, such as: {@code RENAME TABLE customers TO customers_old, customers_copy TO
+         * customers;}.
+         *
+         * <p>In such cases, Debezium's {@link io.debezium.connector.mysql.MySqlDatabaseSchema}
+         * emits two separate change events:
+         *
+         * <ul>
+         *   <li>{@code RENAME TABLE customers TO customers_old}
+         *   <li>{@code RENAME TABLE customers_copy TO customers}
+         * </ul>
+         *
+         * <p>Both events share a table name of {@code customers, customers_old} in their source
+         * info, which includes multiple table IDs in a single string.
+         *
+         * <p>On the other hand, the {@code TableChanges.TableChange#id} correctly identifies the
+         * schema change:
+         *
+         * <ul>
+         *   <li>The change for {@code RENAME TABLE customers_copy TO customers} has the {@code
+         *       customers} ID.
+         *   <li>The change for {@code RENAME TABLE customers TO customers_old} is empty.
+         * </ul>
+         *
+         * <p>The problem arises because {@link
+         * org.apache.flink.cdc.connectors.mysql.debezium.reader.BinlogSplitReader} does not expect
+         * multiple table IDs in the source info. As a result, changes for tables defined by the
+         * table filter configuration (e.g., {@code customers}) may be filtered out unintentionally.
+         * This can lead to schema changes not being saved in the state, which is crucial for
+         * recovering the job from a snapshot.
+         *
+         * <p>To resolve this issue, this method:
+         *
+         * <ol>
+         *   <li>Checks if the source info contains multiple table names.
+         *   <li>Verifies if the {@code TableChange#id} matches one of the table names.
+         *   <li>Updates the source info with the correct table name that conforms to Flink CDC
+         *       expectations, ensuring the schema change is saved correctly.
+         * </ol>
+         *
+         * @param event the schema change event emitted by Debezium.
+         * @return the updated source info with the corrected table name if necessary.
+         */
+        private Struct rewriteTableNameIfNeeded(SchemaChangeEvent event) {
+            Struct sourceInfo = event.getSource();
+            String tableName = sourceInfo.getString(TABLE_NAME_KEY);
+            if (tableName == null || tableName.isEmpty()) {
+                return sourceInfo;
+            }
+
+            List<String> tableNames = parseTableNames(tableName);
+            if (2 <= tableNames.size() && event.getDdl().toLowerCase().startsWith("rename")) {
+                for (TableChanges.TableChange tableChange : event.getTableChanges()) {
+                    String changedTableName = getMatchingTableName(tableNames, tableChange.getId());
+                    if (changedTableName != null) {
+                        LOG.debug(
+                                "Rewrite table name from {} to {} on swapping tables",
+                                tableName,
+                                changedTableName);
+                        sourceInfo.put(TABLE_NAME_KEY, changedTableName);
+                    }
+                }
+            }
+            return sourceInfo;
+        }
+
+        /**
+         * Decodes table names from a comma-separated string.
+         *
+         * <p>This method extracts individual table names from a string where multiple table names
+         * are separated by commas. The input string is constructed by {@link
+         * io.debezium.connector.mysql.SourceInfo}.
+         *
+         * @param tableName a comma-separated string containing multiple table names
+         * @return a list of trimmed table names
+         */
+        private List<String> parseTableNames(String tableName) {
+            return Arrays.stream(tableName.split(","))
+                    .map(String::trim)
+                    .collect(Collectors.toList());
+        }
+
+        private String getMatchingTableName(List<String> tableNames, TableId tableId) {
+            return tableNames.stream()
+                    .filter(name -> name.equals(tableId.table()))
+                    .findFirst()
+                    .orElse(null);
+        }
+
         @Override
         public void schemaChangeEvent(SchemaChangeEvent event) throws InterruptedException {
             historizedSchema.applySchemaChange(event);