28-06-2016 дата публикации
Номер: KR1020160074193A
Принадлежит:
Disclosed are a mapping method and a reducing method for a join operation, and devices using the methods. According to embodiments of the present invention, provided are techniques of effectively performing distributed processing of a join operation through a mapping action and a reducing action consisting of a plurality of stages. The reducing method for a join operation includes the following steps: receiving mapping data including a value of a join key field, a tag, and a value of a record field; outputting the value of the join key field, a first index, and the value of the record field; and repeatedly outputting the value of the join field, a second index, the tag, and the value of the record field. COPYRIGHT KIPO 2016 (110) First table (120) Second table (130) Join key field: item (140,CC) Item purchased together (A1,A2) User (BB) Item (DD) Purchase item (E1,E2,E3,E4,E5,E6,E7) Smartphone (F1,F2,F3) Laptop (G1,G2,G3,G4,G5) Smartphone case (H1,H2,H3,H4,H5) Earphone (I1,I2,3,I4,I5) Charging ...
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