03 Migrate, validate, and rewrite — instructor notes
Operate the UI copy, parity stop gate, and semantic rewrite review.
Timing
Budget 45 minutes. Start the break only after migration is visibly progressing or complete; do not fire validation merely to fit the agenda.
Talk track
Learners click Migrate Data once. The agent may generate Python internally for
migrationkit; emphasize that this is tool execution behind the button, not a learner
command to copy. Quiet chat is expected after dispatch. The Migration view owns progress
and the selected run ID identifies the authoritative run.
The learner guide presents the built-in direct runner and S3 staging in parallel tabs. Keep learners on the first tab: the workshop intentionally avoids provisioning the S3 bucket, credentials, and Unity Catalog external location required by the large-migration path. Explain that S3 staging is a production-scale option, not a prerequisite for completing this lab.
Only after every table completes do learners click Validate. Any mismatch is a hard stop. After parity they click Rewrite Queries, review semantic differences, and save the accepted ClickHouse set through Edit · OLAP for Step 5.
Require redacted screenshots of the selected Migration and Validation views plus the conversation link. A screenshot of chat saying “success” is not a substitute for those dashboard states.
Common failures
- Learners run the Python shown in tool activity and create a duplicate migration.
- Validation begins while a table is still copying.
- The validator errors, but learners accept an ad hoc count quoted in chat as parity.
- A mismatch is patched by hand instead of correcting and re-firing the workflow.
- A rewrite runs but changes NULL, array, JSON, or divide-by-zero semantics.
- The source query pack remains in the editor, so Benchmark pairs the wrong statements.
Reset steps
Return to the run picker, choose one authoritative run, and cancel duplicates without deleting their failure information. Repair schema or transforms through the same chat, then re-fire Migrate Data and Validate. Reopen Edit · OLAP and confirm the accepted target rewrites before continuing.