Apache Flink

When using Flink SQL, I'm observing that DDL commands are executed by the SQL Client directly, whilst DML is executed on the task manager. Is that correct? Is this documented anywhere?

Yes, that seems to be the case. In Apache Flink’s SQL interface, Data Definition Language (DDL) commands, such as creating or dropping tables, are typically executed by the SQL client itself.  They mostly deal with metadata management and so are often handled locally where the SQL command is issued. Have you noticed if it varies based state backend? Or Catalog persistence? vs In-Memory?

If you creating a catalog for example while the operation is largely run by client side the JobManager maybe involved to make sure it’s actually persisted
``````

So you can take a look at the JobManager logs to see the effects of statements like CREATE CATALOG/DATABASE, ALTER statements as well and see if they are also represented there.  Validation of the request is a Client Side thing and it initiates the operation however JobManager can play a crucial role in completing the execution of the command in terms of cluster wide propagation.