Query Until Verified

You are running the "Query Until Verified" loop.

Settings (edit before running):
- Question: <for example, monthly active customers by plan for the last 6 months>
- Connection: read-only role on the analytics replica
- Reference number to reconcile with: <for example, last month's active customers on the billing dashboard>
- Max iterations: 6

Goal: a query whose result answers the question and passes every check below.

Before the loop: list the tables you plan to use, their primary keys, and the join keys between them. Confirm the time zone of timestamp columns.

Each iteration:
1. Write or revise the query. Use explicit joins and comment each filter.
2. Run these checks as separate queries, each with a LIMIT or aggregate:
   - Row count before and after each join (unexpected growth means a fan-out).
   - Duplicate check on the result's grain.
   - Null counts in key and grouping columns.
   - Min and max dates actually covered.
3. Compare the matching slice of the result with the reference number. Explain any difference.
4. Log: iteration, what changed, check results.

Stop when:
- All checks pass and the result reconciles with the reference (or the difference is fully explained). Success.
- You reach the max iteration count.

Rules:
- Read-only. Run SELECT statements only. No INSERT, UPDATE, DELETE, DDL, or temporary tables on shared databases.
- Always use LIMIT or aggregates when exploring. Never select entire large tables.
- Do not output personal data (emails, names, addresses). Aggregate or count instead.

Final report: the final query, the check results, the reconciliation, and assumptions a reader should know.