05 Multiple catalogs — instructor notes
Prepare catalog attachments, then let learners prove them through MigrationRoom chat.
Timing
Budget 35 minutes. Complete secret-bearing catalog attachment before learners enter this module.
Talk track
Attach unity_tpch and rest_catalog_tpch as read-only DataLakeCatalog databases on
the participant ClickHouse service, or provide a tested per-pair service where both
already exist. Do not put attachment credentials or DDL in the learner conversation.
Learners paste the supplied no-Python request into MigrationRoom chat. Require visible
clickhousectl calls for SHOW TABLES, actual counts, and a three-way query joining
native orders, Unity customer, and REST nation. Explain that ClickHouse supports Unity
and other catalogs simultaneously, while metadata, object access, credential vending,
and native RBAC remain separate boundaries.
Be precise about ownership: MigrationRoom demonstrates the query through its UI; the instructor prepared the attachments. Do not present attachment as a seventh button.
Common failures
- Metadata lists successfully but object reads fail.
- The agent prints secret-bearing DDL in chat.
- The hybrid query accidentally uses copied versions of all three tables.
- “Same governance” is claimed across Unity, REST, and native ClickHouse data.
Reset steps
Test catalog metadata, credential vending, object storage, and network reachability separately outside the learner conversation. Rotate any exposed credential. If the live attachments cannot be restored, mark the participant step not executed and use a redacted instructor demonstration only for discussion.