Question

Difference between static and extendable hashing

Answer 1

1. Static hashing - In static hashing, when a search-key value is provided, the hash function always computes the same address. The output address shall always be same for that function. The number of buckets provided remains unchanged at all times. As the file grows, performance decreases. No complex implementation and it is a less attractive technique. The problem with static hashing is that it does not expand or shrink dynamically as the size of the database grows or shrinks.
2. Dynamic Hashing - Dynamic hashing provides a mechanism in which data buckets are added and removed dynamically and on-demand. Dynamic hashing is also known as extended hashing. Hash function, in dynamic hashing, is made to produce a large number of values and only a few are used initially. The Performance does not degrade as the files increase. Although the implementation is complex, it is an attractive technique.