CSC 4710 Lecture Notes - Lecture 17: Candidate Key, Unique Key, Liquid Oxygen

• School: Wayne State University
• Department: Computer Science
• Course: CSC 4710
• Professor: Dali Ismail

Document Summary

Integrated file containing index and rows (index entries contain rows in this case) In this case, the storage structure might be a heap or sorted file, but often is an integrated file with another index (on a different search key typically the primary key) Index must be updated when table is modified. It is generally unclustered (since the organization of rows in the storage structure depends on main index) Dense index: dense index: has index entry for each data record, unclustered index must be dense, clustered index need not be dense, sparse index: has index entry for each page of data file, sparse vs. Find rows with values between (a1, a2) and (a1 , a2 ) . If q pages of index entries, then log2q page transfers (which is a big improvement over binary search of the data pages of a f page data file since f >>q)