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PostgreSQL CROSS JOIN

A CROSS JOIN returns the Cartesian product of two tables, combining each row of one table with every row of another. No ON condition is used.

Example

SELECT c.customer_id, o.order_id
FROM customers c
CROSS JOIN orders o;

Best Practices

  • Be cautious with large tables; a CROSS JOIN can produce massive result sets.
  • Use CROSS JOIN only when you specifically need every combination of rows.

Key Takeaways

  • CROSS JOIN pairs each row in the left table with each row in the right table.
  • No join condition is used, so the result is a Cartesian product.
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