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Normalization vs Denormalization
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Normalization vs Denormalization

MediumSQL · PostgreSQL

Problem

What are the primary differences between data normalization and denormalization, and how do they impact pipeline design?

Use the provided normalized and denormalized order-line representations to quantify duplication and consistency differences. Write one SQL query that returns the comparison metrics.

Output

  1. One row containing the normalized and denormalized line counts, order counts, distinct product counts, repeated attribute rows, and denormalized attribute mismatches.
  2. Use the exact output column names defined by the solution.

Schema

products
ColumnTypeDescription
product_idPKINTUnique product identifier
product_nameVARCHAR(100)Authoritative product name
categoryVARCHAR(80)Product category
normalized_order_items
ColumnTypeDescription
item_idPKINTUnique normalized order-line identifier
order_idINTOrder identifier
product_idINTReferenced product identifier
quantityINTQuantity ordered
denormalized_order_items
ColumnTypeDescription
item_idPKINTUnique denormalized order-line identifier
order_idINTOrder identifier
product_idINTReferenced product identifier
product_nameVARCHAR(100)Copied product name
categoryVARCHAR(80)Copied product category
quantityINTQuantity ordered
Tablesproductsnormalized_order_itemsdenormalized_order_items
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