24-DeducDatabases

24-DeducDatabases - Discussion#24 Deductive Databases 1/21 Discussion#24 Deductive Databases Discussion#24 Deductive Databases 2/21 Topics •

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Discussion #24 Deductive Databases 1/21 Discussion #24 Deductive Databases Discussion #24 Deductive Databases 2/21 Topics • Deductive Databases • Turning Datalog into Relational Algebra • Recursive Rules & the Least Fixed Point Algorithm Discussion #24 Deductive Databases 3/21 Deductive Databases • Deductive database management systems answer queries based on methods related to proofs from rules and facts. • Relational algebra operations can be used to more efficiently process deductive database queries. Discussion #24 Deductive Databases 4/21 Correspondence Between Relational Databases & Deductive Databases Schemes: f(A,B) b(C,D) Facts: f(1,1). f(1,2). f(2,3). Rules: b(x,y) :- f(y,x). b(x,y) :- f(x,z),f(z,y). Queries: b(1,x)? f(A, B) b(C, D) 1 1 1 2 2 3 b ← b ∪ ρ x ← C ρ y ← D π xy ( ρ A ← y ρ B ← x f ) b ← b ∪ ρ x ← C ρ y ← D π xy ( ρ A ← x ρ B ← z f | × | ρ A ← z ρ B ← y f) π x ρ D ← x σ C=1 b Discussion #24 Deductive Databases 5/21 Correspondence Between Relational Databases & Deductive Databases Schemes: f(A,B) b(C,D) Facts: f(1,1). f(1,2). f(2,3). Rules: b(x,y) :- f(y,x). b(x,y) :- f(x,z),f(z,y). Queries: b(1,x)? f(A, B) b(C, D) 1 1 1 1 1 2 2 1 2 3 3 2 b ← b ∪ ρ x ← C ρ y ← D π xy ( ρ A ← y ρ B ← x f ) b ← b ∪ ρ x ← C ρ y ← D π xy ( ρ A ← x ρ B ← z f | × | ρ A ← z ρ B ← y f) π x ρ D ← x σ C=1 b Discussion #24 Deductive Databases 6/21 Correspondence Between Relational Databases & Deductive Databases Schemes: f(A,B) b(C,D) Facts: f(1,1)....
View Full Document

This note was uploaded on 03/02/2012 for the course C S 236 taught by Professor Michaelgoodrich during the Winter '12 term at BYU.

Page1 / 17

24-DeducDatabases - Discussion#24 Deductive Databases 1/21 Discussion#24 Deductive Databases Discussion#24 Deductive Databases 2/21 Topics •

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online