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https://dev.mysql.com/doc/refman/8.4/en/function-optimization.html
A function is nondeterministic if, given fixed values for its arguments, it can return different results for different invocations. If a function is tagged nondeterministic, a reference to it in a WHERE clause is evaluated for every row (when ...
https://dev.mysql.com/doc/refman/8.4/en/generated-column-index-optimizations.html
For example: CREATE TABLE t1 (f1 INT, gc INT AS (f1 + 1) STORED, INDEX (gc)); The generated column, gc, is defined as the expression f1 + 1. The column is also indexed and the optimizer can take that index into account during execution plan ...
https://dev.mysql.com/doc/refman/8.4/en/geometry-well-formedness-validity.html
Spatial import functions that parse WKT or WKB values raise an error for attempts to create a geometry that is not syntactically well-formed. For geometry values, MySQL distinguishes between the concepts of syntactically well-formed and ...
https://dev.mysql.com/doc/refman/8.4/en/gone-away.html
If you want to create a bug report regarding this problem, be sure that you include the following information: Indicate whether the MySQL server died. This section also covers the related Lost connection to server during query error. The most ...
https://dev.mysql.com/doc/refman/8.4/en/group-by-functional-dependence.html
The following discussion provides several examples of the ways in which MySQL detects functional dependencies. The examples use this notation: {X} -> {Y} Understand this as “X uniquely determines Y,” which also means that Y is functionally ...
https://dev.mysql.com/doc/refman/8.4/en/group-by-modifiers.html
The GROUP BY clause permits a WITH ROLLUP modifier that causes summary output to include extra rows that represent higher-level (that is, super-aggregate) summary operations. ROLLUP thus enables you to answer questions at multiple levels of ...
https://dev.mysql.com/doc/refman/8.4/en/group-by-optimization.html
The most general way to satisfy a GROUP BY clause is to scan the whole table and create a new temporary table where all rows from each group are consecutive, and then use this temporary table to discover groups and apply aggregate functions (if ...
https://dev.mysql.com/doc/refman/8.4/en/group-replication-change-primary.html
This section explains how to change which member of a single-primary group is the primary, using the group_replication_set_as_primary() function, which can be can be run on any member of the group. When this is done, the current primary becomes a ...
https://dev.mysql.com/doc/refman/8.4/en/group-replication-deploying-instances.html
In this example, three instances are used for the group, which is the minimum number of instances to create a group. The first step is to deploy at least three instances of MySQL Server, this procedure demonstrates using multiple hosts for the ...
https://dev.mysql.com/doc/refman/8.4/en/group-replication-getting-started.html
This section provides a detailed tutorial with the steps required to create a replication group with at least three members. MySQL Group Replication is provided as a plugin for the MySQL server; each server in a group requires configuration and ...