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Category: Query optimisation

How to return random rows from a table

Federico Razzoli June 25, 2019December 8, 2019 3 Comments

Returning random rows in a random order from a relational database is a very hard problem. In this article we will see an antipattern, we will discuss why this problem is so hard, and we’ll examine some imperfect solutions.

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Query optimisation

Paginating the results of an SQL query

Federico Razzoli June 21, 2019December 17, 2019 6 Comments

One of the trickiest problems in SQL is to query rows in tranches. This is typically needed in a website search, or in a dynamic catalogue where products appear as you scroll down. You want the DBMS to only return …

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Query optimisation

MySQL/MariaDB: run less queries! (thanks to performance_schema)

Federico Razzoli May 3, 2019April 1, 2020 Leave a comment

Do you want to improve your application’s and database server’s performance? Remove useless queries. Yes, you probably have them.

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Query optimisation

Searching a phone book and copying names

Federico Razzoli March 14, 2019April 1, 2020 Leave a comment

Why developers need to learn the basics of query optimisation. How to make the learning process easy and pleasant.

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Query optimisation

MySQL: IS NULL conditions and indexes (→Vettabase)

Federico Razzoli March 8, 2019November 17, 2020 3 Comments

It is quite common to use an equality condition and an IS NULL condition on the same columns. Unfortunately, this could make queries very slow.

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Query optimisation

Recent Articles

  • DROP TABLE improvements in MariaDB (→Vettabase)
  • MariaDB RETURNING Statements (→Vettabase)
  • Do languages need NULL? – Rust example
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  • MySQL backup methods comparison
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