arXiv:1206.6646v1 [cs.DB] 28 Jun 2012
Aggregate Skyline Join Queries: Skylines with Aggregate Operations over Multiple Relations Arnab Bhattacharya B. Palvali Teja
[email protected] [email protected] Dept. of Computer Science and Engineering, Amazon Development Limited, Indian Institute of Technology, Kanpur, Hyderabad, Kanpur, India India
Abstract
For every attribute, there is a preference function that states which objects dominate over other objects. For example, the preference function for both price and distance to beach is B.b A.a ≥ B.b
conjunction of j comparisons between the corresponding j attributes (hij ) of A and B. In this paper, we assume that join attributes are separate from local and aggregate attributes. The final joined relation R = R1 ⋊ ⋉ R2 is R = {h11 , . . . , h1j , h21 , . . . , h2j , l11 , . . . , l1m1 , l21 , . . . , l2m2 , g11 ⊕1 g21 , . . . , g1n ⊕n g2n }
u ∈ A ≻ u′ ∈ A if
v ∈ B ≻ v ′ ∈ B if
u.a = u′ .a u.a ≤ u′ .a u.a ≤ u′ .a u.a ≥ u′ .a u.a ≥ u′ .a
v.b = v ′ .b v.b ≥ v ′ .b v.b ≥ v ′ .b v.b ≤ v ′ .b v.b ≤ v ′ .b
Table 2: Converting join conditions to skyline preferences.
where ⊕i , etc. denote the join condition. For the example in Table 1, the local attributes are amn and rtg, the aggregate attributes are cost and duration, and the join attributes are dst and arr for FlightsA, and src and dep for FlightsB. The AGGREGATE S KYLINE J OIN Q UERY (ASJQ) is defined as:
well. For example, if ⊙ denotes =, then this translates to u.a = u′ .a (both being equal to v.b); if ⊙ denotes
