Star schema

Keep a star schema plan in step with its source

Source schemas change: columns get added, types widen, and old columns disappear. A drift check compares each plan item’s mappings with the current columns of its source and lists every difference. Some differences are safe for Kenseme to fix. Others need a decision from you.

In the app: Data Model › Schemas › your source schema › Star Schema tab › a plan › Source Drift

[screenshot]
The Source Drift panel with findings grouped by item: a blue NewColumn finding, an orange TypeChange, and a red DroppedColumn blocker with its "Open the pipeline" link.

When drift is checked

  • Automatically after a schema import into the source schema finishes. Every plan built on that schema is checked.
  • On demand when you click Check Drift.

The Source Drift panel on the plan dashboard starts collapsed when there is nothing to report and says No open drift findings. Run a drift check after the source schema changes.

Run a drift check

  1. Open the plan and expand Source Drift.
  2. Click Check Drift. A toast says Drift check started, and the panel refreshes when the check is done.
  3. Read the summary, for example 4 open · 1 blocker(s). Item cards on the dashboard also show a count badge, such as 2 drift.

Read the findings

Findings are grouped by item. Each one shows its kind, the column, and the old and new values where they apply.

Kind Severity Meaning Auto-heal
NewColumn Info The source has a column the item doesn’t map. Yes
TypeChange Warning A mapped column’s data type changed. Yes
DroppedColumn Blocker A mapped column no longer exists in the source. No
BusinessKeyImpact Blocker A business-key column was dropped or changed type. No
HashImpact Blocker A column used to detect SCD2 changes changed type, which changes how history is tracked. No

Columns are matched by name, ignoring case. A renamed column shows up as a dropped column plus a new one.

Heal the safe findings

Click Heal n safe finding(s). Kenseme updates the item’s mappings for every NewColumn and TypeChange finding. A toast says Healing safe findings, and the panel refreshes when it’s done.

After healing, regenerate the affected load procedures with Regenerate Procedures. See Finish and deploy a star schema plan.

Resolve blockers

Blockers are marked Not auto-healable — resolve in the Pipeline mapping editor, then re-run the drift check.

  1. Click Open the pipeline on the finding.
  2. Fix the mapping in the Pipeline, for example map the business key to its replacement column.
  3. Return to the plan and click Check Drift again.

Refresh stale prompts

When an item loads from a source view, any drift also marks the item’s AI prompts as possibly stale, because the view may need rewriting. A Refresh Prompts (n) button then appears in the panel.

Click it to have AI rewrite the prompts for every flagged item. A toast says Prompt refresh started for n item(s). Then open each item and regenerate its view or procedure. This counts toward your AI usage.

You can also refresh one item from its Step C page, where a banner says The source schema changed since this item was designed — its prompts may be stale.

Dismiss a finding

If a finding doesn’t matter, for example a new audit column you don’t want in the star schema, click Dismiss on it and confirm. Later drift checks won’t re-open it.