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1
Query Processing: The Basics
Chapter 10
(animations)
2
Merge: An Example
2 3 5 6
1 7 10 15
Input buffersOutput buffer
1 2 3 5 6 7 10 15
2 3
1 7
5 6
10 15
1 23 56 710 15
Output runInput runs
3
Duplicate elimination During Merge
2 3 5 6
1 3 5 15
Input buffersOutput buffer
1 2 3 5 6 15
2 3
1 3
5 6
5 15
1 23 56 15
Output runInput runs Last key used
1215356
Key 3 ignored: duplicate
Key 5 ignored: duplicate
4
Block-Nested Loop Illustrated
Output buffer
s
r
Input buffer for s
Input buffer for r
… and so on
r s
5
Join During Merge Illustrated
1 3p p
r
s
DA
BE
p p4 0
0 9q q
r9
8 7 3s s s
s7
t t2 5
u u u2 5 0
5 7u u
1 1v v
x0
1 3 1 3p p p pp p p p4 0 0 4
8 7 3s s ss s s7 7 7
5 7 5 7 5 7u u u u u uu u u u u u2 2 5 5 0 0
r A=B s