Index

Question

S1 is true and S3 is False as secondary index is dense...Please explain whether S2 is true or false

Answer 1

Dense Index are faster in general as they point to contiguous memory location. Each Dense Index points to a certain Record therefore there only single access is required.

In Sparse Index the Index points to the Record having the highest Key. All other records are traversed by pointer from the record having highest value. In short First the Record with highest Value is selected (1 Disk Access). This record has further records attached to it by linked List.This List is iterated to get the desired block.(Multiple Disk Access)

Comments

secondary index on key is dence bt on nonkey can be dense or sparse hence S3 is true

Answer 2

i think (2) option is true becoz in dense index we made entry of each record of data file with helf of

<SEARCH KEY,BLOCK_POINTER> so with this field in index file we can access the data file record easily as compared to sparse INDEX.!