Slideshow:
Multiple-key index (file)
Schematically:
Multiple-key index - Example
Input data:
Multiple-key index - Example
Input data:
Group the input data by common "Age" value:
Multiple-key index - Example
Group the input data by common "Age" value:
The multiple-key index file:
- Multiple-key index:
- Multiple-key index =
a
multi-level index
using
different types
of search keys
in different levels
(Multi-level index: see click here )
- Multiple-key index =
a
multi-level index
using
different types
of search keys
in different levels
- Schematically:
- Data on people who buy jewelry:
(age, salary (in $1,000)) A(25,60) D(45,60) G(50,75) J(50,100) B(50,120) E(70,110) H(85,140) K(30,260) C(25,400) F(45,350) I(50,275) L(60,260)
- A multiple-key index
using level 1 is age
and level 2 is salary:
- Separate the
data by
age:
(age, salary (in $1,000)) A(25,60) C(25,400) K(30,260) D(45,60) F(45,350) B(50,120) G(50,75) I(50,275) J(50,100) L(60,260) E(70,110) H(85,140)
- Create an
index file for
each age value:
- Separate the
data by
age: