Scalar subquery unnesting is a transformation technique used by the MySQL optimizer to optimize queries that involve scalar subqueries. Scalar subqueries are subqueries that return a single value, typically used in expressions or as part […]
Locks and wait events can significantly impact MySQL performance as they can cause queries to wait, leading to slower response times and decreased performance. The main cause of lock and wait events is contention for […]
MySQL Hot Tables are tables that experience a high volume of traffic and activity, and can quickly become a bottleneck for database performance. When you see higher than expected disk I/O on MySQL Hot Tables, […]
When adding indexes or columns in MySQL, it is important to be aware of the potential for replication to break. One way to prevent this is to use a tool like pt-online-schema-change from the Percona […]
In MySQL 8, invisible indexes are a feature that allows you to create an index without it being used by the optimizer. This can be useful in situations where you want to test the impact […]
In MySQL, if the server crashes after an update and the transaction was not committed, the changes made by the transaction will be rolled back during the crash recovery process. This is because MySQL uses […]
The impact of ordered versus random index insertion in InnoDB depends on several factors, including the size and complexity of the table, the frequency of inserts, and the workload of the database. Ordered index insertion […]
InnoDB Mutexes are synchronization objects used by the InnoDB storage engine to ensure that different threads can access shared resources safely. Mutex waits can be a bottleneck for performance in MySQL 8, as they can […]
Group commit in MySQL 8 enables the server to batch multiple write operations into a single transaction, improving performance. When multiple transactions execute write operations concurrently, group commit reduces the overhead of disk I/O operations […]
MySQL can ignore histograms in the query optimizer when it determines that using the histograms would not provide any benefit to the query execution plan. This can occur in several cases, including: Why MySQL ignores […]
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