Data Modelling Study Portal

Key takeaways

• Relational is the default because it answers questions you did not design for. Move off it for a measured, specific pattern.
• Name the NoSQL family and its specific trade; "NoSQL scales better" is not an argument.
• Search and graph stores are projections, not systems of record. Keep a rebuildable authoritative copy.
• Composite index column order matters: equality predicates first, then ranges, per the leftmost-prefix rule.
• Every index taxes every write. Never-scanned indexes are pure cost and are easy to find.
• Keep the indexed column bare in predicates, or index the expression instead.
• Denormalise for read-heavy paths, but keep the normalised source authoritative and rebuildable.