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Set operations are a part of relational algebra

• Two relations are union-compatible if their column metadata definitions match.

• I.e., same column names and types, and in the same order.

• The relational algebra includes set operations on union-compatible relations:
  • Union: ∪
  • Intersect: ∩
  • Difference: −

Other operations

• Cartesian Product: ×

• Rename: ρ

• Select: σ

• Project: Π

• Natural Join: ⨝

• Divide: ÷

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