Explain Hashing techniques.
1 Answer



  • Hashing technique is used to calculate the direct location of a data record on the disk without using index structure.
  • That is used to index and retrieve items in a database as it is faster to search that specific item, using the shorter hashed key instead of using its original value.

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  • A hash function is a simple mathematical function to any complex mathematical function.

Types of Hashing Techniques:

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There are two types of SQL hashing techniques:

(I) Static Hashing

(II) Dynamic Hashing

(I) Static Hashing Techniques:

  • Static hashing is the number of data buckets in memory remains constant throughout.
  • That is a method of hashing, or shortening a string of characters in computer programming, in which the set of shortened characters remains the same length to improve the ease with which data can be accessed.

Static Hash Functions:

  • Inserting a record:

When a new record requires to be inserted into the table, you can generate an address for the new record using its hash key and record is stored in that location.

  • Searching a record:

When you need to retrieve the record, the same hash function should be helpful to retrieve the address of the bucket where data should be stored.

  • Update a Record:

we will first search it using a hash function, and then the data record is updated.

This situation in the static hashing is known as bucket overflow, This is a critical situation in this method.

(II) Dynamic Hashing:

  • In dynamic hashing, the hash function helps you to create a large number of values.

  • This method is used to overcome the problems of static hashing like bucket overflow.

  • This hashing is provides a mechanism, in which data buckets are added and removed dynamically and on-demand.

  • Dynamic hashing is also known as extended hashing.

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