Dynamic Hashing
In dynamic hashing, Data buckets grow or shrink (dynamically added or removed) as the data set grows or shrinks. Dynamic Hashing is also known as Extended Hashing. Dynamic hashing requires the hash function to generate a large number of values.
For example, there are three data sets: Data1, Data2, and Data3.
The hash function produces three addresses 1010, 1011, and 1001.
This storage method only considers part of this address, specifically the first bit that stores the data.
So we try to load three of them into addresses 0 and 1.
h(Data 1) -> 1010
h(Data 2) -> 1011
h(Data 3) -> 1001
But the problem is that there are no bucket addresses left for Data3. Buckets must be dynamically expanded to support D3. Therefore, we change the address by 2 bits instead of 1 bit and update the existing data to have a 2-bit address.
Next, try to record data 3.
Hash File Organization in DBMS
Hashing techniques are used to retrieve specific data. Searching through all index values to reach the desired data becomes very inefficient, in this scenario we may use hashing as an efficient technique for locating desired data directly on disk without using an index structure.
Hash File Configuration is also known as Direct file configuration.
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