lvyanquan commented on code in PR #3932:
URL: https://github.com/apache/flink-cdc/pull/3932#discussion_r1974878864
##########
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:
##########
@@ -99,23 +100,17 @@ protected void processElement(
alreadySendCreateTableTables.add(tableId);
}
}
- } else if (splitState.isBinlogSplitState() &&
!alreadySendCreateTableForBinlogSplit) {
- alreadySendCreateTableForBinlogSplit = true;
- if
(sourceConfig.getStartupOptions().startupMode.equals(StartupMode.INITIAL)) {
- // In Snapshot -> Binlog transition of INITIAL startup mode,
ensure all table
- // schemas have been sent to downstream. We use previously
cached schema instead of
- // re-request latest schema because there might be some
pending schema change events
- // in the queue, and that may accidentally emit evolved schema
before corresponding
- // schema change events.
- createTableEventCache.stream()
- .filter(
- event ->
- !alreadySendCreateTableTables.contains(
-
MySqlSchemaUtils.toDbzTableId(event.tableId())))
- .forEach(output::collect);
- } else {
- // In Binlog only mode, we simply emit all schemas at once.
- createTableEventCache.forEach(output::collect);
+ } else {
+ if (isDataChangeRecord(element) || isSchemaChangeEvent(element)) {
+ TableId tableId = getTableId(element);
+ if (!alreadySendCreateTableTables.contains(tableId)) {
+ CreateTableEvent createTableEvent =
createTableEventCache.get(tableId);
+ // New created table in binlog reading phase.
Review Comment:
This is indeed a problem, but it is different from the one I hope to solve
here.
For DataChange, perhaps we can derive the schema from `SourceRecord` instead
of using SQL to query the latest schema. But to make this problem more
difficult, if we start reading from a position where SchemaChange happened, we
cannot derive the original schema.
```
--- Create Table A --> Alter Table A Add a column--> Table A Binlog -->
Startup Offset --->
^
|
What if we start from here?
```
So I think starting from a position where historical schema is different
with the current schema is still an unresolved issue for us.
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