Do we use hash tables in practice?

Question

I just read about Hash tables and I wonder if we will use it in practice, because if I write a program that stores data in a Hash table, the storage will only be temporary. So, why not use a database to store it?

In other words, what real-world programs use hash tables to function?

Answer 1

You must use hash tables to store data while you work. Using a database for this in many cases will be several orders of magnitude slower than using hash tables in memory. See for example:

• http://en.wikipedia.org/wiki/Caching

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Uses Hash table :

• http://en.wikipedia.org/wiki/Hash_table

Answer 2

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Answer 3

<x> the hash table is designed for quick access, say that you need to look for a lot of records, which will be very expensive. Using a hash function will lead you to almost the part that you want to execute. And you can implement a hash table of the database schema, so they are not necessarily temporary storage.