Practice database schema review vocabulary: missing indexes, ambiguous column names, NOT NULL constraints, migration requirements, and schema approval language.
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A schema review comment says 'Missing index on the foreign key column.' Why is this a common schema issue?
Foreign key columns are frequently used in JOINs and WHERE clauses. Without an index, every such query requires a full table scan. Most databases do not automatically create indexes for foreign keys (unlike primary keys), making this one of the most common and impactful schema review findings.
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A reviewer says 'The column name is ambiguous — rename to be explicit.' An example is renaming 'status' to 'order_status.' Why does this matter?
Ambiguous column names like 'status', 'type', or 'date' are common in schemas with many tables and cause confusion in multi-table queries. When reviewing a query using a generic 'status' column, it's unclear which entity's status it refers to. Explicit names improve readability and reduce bugs.
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A schema review flags 'The nullable column should have a NOT NULL constraint.' When is this the correct recommendation?
Columns that should always have a value — foreign keys, required fields, audit timestamps — should be NOT NULL. Allowing NULL when a value should always exist leads to incomplete records that break application logic, produce incorrect aggregates, and require defensive null checks everywhere.
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A reviewer says 'The schema change requires a migration.' What does a database migration involve?
A database migration is a version-controlled script that transforms an existing schema from one state to another. Migrations must be written carefully for production — considering backward compatibility (can old and new app code run simultaneously?), performance (large table changes under load), and rollback strategy.
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A schema review ends with 'The reviewing engineer approved the schema design.' What does this approval typically confirm?
Schema approval in a review confirms the design is sound: data types are appropriate, constraints enforce business rules, indexes support expected query patterns, naming follows conventions, and the migration strategy is safe for the production environment. It is a quality gate, not a rubber stamp.