Explain Hashing techniques

The hashing techniques can be categorized as: Static Hashing Techniques - In this method, the data can be viewed a collection of buckets, along with one primary page and probably additional overflow pages per bucket. A file contains buckets 0 through N-1, with one primary page per bucket basically and additional overflow pages chained with bucket, if needed later. Buckets consist of data entries (or data records). A main drawback of the static hashing is that the hash address space is fixed. Therefore, it is hard to expand or shrink the file dynamically.