week10 - Inverted File Structures: Emp-no 01 02 04 05 06...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Inverted File Structures: Emp-no Emp-name Dept No.of dependents Salary 01 Jane Gun 1 02 George Shoe 2 04 Dave Shoe 3 05 Mary Gun 2 06 Mike Shoe 1 Inverted indexes for secondary attribute Time needed to access posting lists is a function of their length and their allocation. n: number of blocks 85% of are sequentially allocated file needed to access posting list= n*0.15*(s+r+btt) +(s+r) +n*0.85*ebt Display Emp-name where Dept= “Shoe” and No.of dependents=2 How many employees in the result set?
Background image of page 1

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

View Full DocumentRight Arrow Icon
It depends on the selectivity of the attributes. R(no. of records)=10000 Condition No. of hits Dept=Gun 0.10*10000=1000 List Structured Files
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 9

week10 - Inverted File Structures: Emp-no 01 02 04 05 06...

This preview shows document pages 1 - 3. Sign up to view the full document.

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