The most widely known query optimisation rule is that developers should always avoid SELECT *. Even when all columns are needed, they should list their names, because more columns could be created in the future. But developers find this really Continua a leggere How slow is SELECT * ?
Some queries always fail or never return rows. They should be eliminated to improve database performance. Continua a leggere Identify useless queries in MariaDB/MySQL
Comparisons are tricky when NULL values are involved. But some databases offer some special, handy syntax to solve the problem. Continua a leggere NULL comparisons in MariaDB, PostgreSQL, and SQLite
Having many indexes in our databases comes with a cost. It is good to periodically eliminate duplicate and unused indexes. Continua a leggere Finding Duplicate Indexes and Unused Indexes in MariaDB/MySQL
MariaDB/MySQL replication filters may be useful, but they come with some risks that Database Administrators should be aware of. Continua a leggere The risks of replication filters in MariaDB and MySQL
An oversized InnoDB buffer pool will consume too many resources and can be slower than necessary. Let’s see how to check if we can shrink it. Continua a leggere Can we shrink InnoDB Buffer Pool?
InnoDB buffer pool is the most important memory area to allocate. It contains the most frequently read data and index entries from InnoDB tables. Let’s see how to check if it is big enough. Continua a leggere Is InnoDB Buffer Pool big enough?
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. Continua a leggere MariaDB/MySQL IS NULL conditions and indexes
AUTO_INCREMENT primary keys are useful, because they save usthe trouble to generate a unique value for every row, delegating this task to the database. But when we reach the limit we need to take some action, or we won’t be able to insert more rows. Continua a leggere Monitoring that AUTO_INCREMENT values won’t reach the limit
Reducing the number of queries is important with any DBMS. There are two reasons for this: reducing the latency of applications; and reducing the workload for the database servers. Continua a leggere MariaDB/MySQL: use SQL properly to run less queries