In the official documentation for impala here, the statestore component has a statement:
If you issue a DDL statement while the statestore is down, the queries that access the new object the DDL created will fail.
Correct me if I'm wrong but the metadata changes that are made through Impala SQL are propagated to Impala Daemons from the Impala Catalog Service. Then why would the query on the new object generated through a DDL fail if the statestore is down?
Just a small correction in your understanding, The documentation says the below
The Impala component known as the catalog service relays the metadata changes from Impala SQL statements to all the Impala daemons in a cluster.
So basically it relays the metadata changes to the Impala daemons through the StateStore. You will also see the below in the documentation,
Because the statestore's purpose is to help when things go wrong and to broadcast metadata to coordinators
So, any metadata changes are relayed by the Catalog service to Impala daemons through the Statestore service.
In Simple words, the Impala daemons and Statestore are always in connection when Statestore is up and running. Statestore takes care of
Monitoring all the Impala daemons and letting other Impala daemons know if any health issues found on one of the daemons (such as daemon going down).
It broadcasts the metadata changes to the Impala daemons when query is executed and during Invalidate Metadata.
Hope that helps!