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10.2.2.2 Optimizing Subqueries with Materialization

https://dev.mysql.com/doc/refman/9.7/en/subquery-materialization.html

The index contains unique values to eliminate duplicates and make the table smaller. The optimizer uses materialization to enable more efficient subquery processing. Materialization speeds up query execution by generating a subquery result as a ...

10.4.3.1 How MySQL Opens and Closes Tables

https://dev.mysql.com/doc/refman/9.7/en/table-cache.html

Also take into account that the MyISAM storage engine needs two file descriptors for each unique open table. When you execute a mysqladmin status command, you should see something like this: Uptime: 426 Running threads: 1 Questions: 11082 Reloads: ...

27.4.1 Trigger Syntax and Examples

https://dev.mysql.com/doc/refman/9.7/en/trigger-syntax.html

Trigger names exist in the schema namespace, meaning that all triggers must have unique names within a schema. To create a trigger or drop a trigger, use the CREATE TRIGGER or DROP TRIGGER statement, described in Section 15.1.26, “CREATE TRIGGER ...

13.3.5 The VECTOR Type

https://dev.mysql.com/doc/refman/9.7/en/vector.html

This includes all of the following types: Primary key Foreign key Unique key Partitioning key A VECTOR column also cannot be used as a histogram source. A VECTOR is a structure that can hold up to a specified number of entries N, defined as shown ...

1.2.1 What is MySQL?

https://dev.mysql.com/doc/refman/9.7/en/what-is-mysql.html

You set up rules governing the relationships between different data fields, such as one-to-one, one-to-many, unique, required or optional, and “pointers” between different tables. MySQL, the most popular Open Source SQL database management ...

10.2.1.1 WHERE Clause Optimization

https://dev.mysql.com/doc/refman/9.7/en/where-optimization.html

A table that is used with a WHERE clause on a PRIMARY KEY or a UNIQUE index, where all index parts are compared to constant expressions and are defined as NOT NULL. This section discusses optimizations that can be made for processing WHERE clauses.