Hello Team, We are currently using Apache Druid 37.0.0 and are exploring whether MSQ or Druid SQL supports querying/joining directly against external catalog tables, specifically Iceberg tables registered in an AWS Glue Catalog. Our goal is to execute a query similar to:

SELECT ...
FROM druid_datasource d
JOIN glue_catalog.some_database.some_iceberg_table i
  ON d.id = i.id

without first ingesting the Iceberg table into a Druid datasource. From the current Druid documentation, it appears that the Iceberg extension supports AWS Glue Catalog, but primarily through the

IcebergInputSource

, where the Iceberg data is read and ingested into Druid. We also see that MSQ supports

JOIN

operations and can read external data through

EXTERN

, but we are not clear whether an Iceberg/Glue Catalog table can be used directly as a queryable table source in an MSQ query. Could you please clarify: 1. Does Druid 37.0.0 support direct SQL/MSQ queries against Iceberg tables registered in AWS Glue Catalog? 2. If not, is this supported in any newer Druid version? 3. Is there currently a way to perform a JOIN between a Druid datasource and an Iceberg/Glue Catalog table without first ingesting the Iceberg data into Druid? 4. If this is not currently supported, is there an alternative approach or planned feature that would enable this type of federated query? Our use case is to avoid an additional ingestion step where possible and directly leverage the existing Iceberg/Glue Catalog data for joins and transformations. Reference: Druid Iceberg Ingest Extension Documentation - druid.apache.org/docs/…/iceberg#…