| # Analysis Guidance — CROSS2_schema_evolution |
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| ## Tools to run |
| - `cat service_a/migrations/002_add_columns.py` — CRITICAL: shows all schema changes |
| - `cat service_a/config.py` — read default values for backfill |
| - `cat shared/schema.sql` — expected final schema |
| - `cat service_b/models.py` — compare with migration to find staleness |
| - `grep -n "SELECT \*" service_b/queries.py` — find unsafe queries |
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| ## Key Findings |
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| ### Schema changes (from migration 002): |
| 1. Column RENAMED: `user_name` → `username` (breaking change) |
| 2. Column ADDED: `email_verified` (boolean, default: False) |
| 3. Column ADDED: `last_login_at` (datetime, default: None) |
| 4. Column ADDED: `account_tier` (string, default: from config DEFAULT_TIER) |
| |
| ### Service B staleness: |
| - `service_b/models.py` `User` class still has `user_name` attribute (wrong) |
| - `service_b/models.py` missing `email_verified`, `last_login_at`, `account_tier` fields |
| - `service_b/queries.py` has 2 queries using `SELECT *` — will break with new columns |
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|
| ### Backfill defaults (from service_a/config.py): |
| - `email_verified`: False |
| - `last_login_at`: None |
| - `account_tier`: `DEFAULT_TIER` constant (read its value from config.py) |
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|
| ## Tell Executor |
| 1. In `service_b/models.py`: rename `user_name` → `username`, add 3 new fields |
| 2. In `service_b/queries.py`: replace both `SELECT *` with explicit column lists |
| 3. In `scripts/backfill.py`: UPDATE all existing rows setting the 3 new columns to defaults |
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