How much faster is the denormalized form of the database from the normalized one?

A

a_halala2017-04-03 17:05:10

SQL

a_halala, 2017-04-03 17:05:10

Hello. I cannot find specific examples or experience of denormalization and its advantages over normalization for large systems (relational databases, of course). Interested in comparing the speed of queries in two forms (for example, 3rd normal form and denormalized form) for data sampling. Who can advise on this topic?
P.S. I am looking for this information for my graduation project.

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2 answer(s)

R

Roman Kitaev, 2017-04-03
@deliro

Isn't it obvious? Example:
1) Normal form - do not store the amount of money the user has, but calculate them as the sum of changes in transactions. Let's say a user has 1 million transactions. It is necessary to aggregate 1 million tuples of the table.
2) Denormalized form - store the user's amount of money as a field for the user. To find them out, you just need to pull out one tuple - the user's record.

C

coderisimo, 2017-04-05
@coderisimo

Here with examples.
normal forms i-novice.net/6-normalnyx-form-bd
Next, you can install mySQL yourself and run tests - it should turn out visually and interestingly.
BUT, as it turned out, denormalization does not always provide great speed:
https://ruhighload.com/post/%D0%94%D0%B5%D0%BD%D0%...
:)))
But the convenience of working with data and a guarantee that there are no errors when working with data - more often yes than no)