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https://dev.mysql.com/doc/refman/8.4/en/thread-information.html
To ascertain what your MySQL server is doing, it can be helpful to examine the process list, which indicates the operations currently being performed by the set of threads executing within the server. row *************************** Id: 5 User: ...
https://dev.mysql.com/doc/refman/8.4/en/trace-general-structure.html
A trace follows the actual execution path very closely; for each join, there is a join preparation object, a join optimization object, and a join execution object. Query transformations (IN to EXISTS, outer join to inner join, and so on), ...
https://dev.mysql.com/doc/refman/8.4/en/trigger-metadata.html
To obtain metadata about triggers: Query the TRIGGERS table of the INFORMATION_SCHEMA database.
https://dev.mysql.com/doc/refman/8.4/en/union.html
query_expression_body UNION [ALL | DISTINCT] query_block [UNION [ALL | DISTINCT] query_expression_body] [...] query_expression_body: See Section 15.2.14, “Set Operations with UNION, INTERSECT, and EXCEPT” UNION combines the result from multiple ...
https://dev.mysql.com/doc/refman/8.4/en/update-optimization.html
An update statement is optimized like a SELECT query with the additional overhead of a write. The speed of the write depends on the amount of data being updated and the number of indexes that are updated. Another way to get fast updates is to delay ...
https://dev.mysql.com/doc/refman/8.4/en/upgrade-best-practices.html
Usually, newer MySQL versions add features and improve performance but there are cases where an upgrade might run slower for specific queries. MySQL supports upgrading between minor versions (within an LTS series) and to the next major version ...
https://dev.mysql.com/doc/refman/8.4/en/validate-password.html
The validate_password component serves to improve security by requiring account passwords and enabling strength testing of potential passwords. This component exposes system variables that enable you to configure password policy, and status ...
https://dev.mysql.com/doc/refman/8.4/en/view-metadata.html
To obtain metadata about views: Query the VIEWS table of the INFORMATION_SCHEMA database.
https://dev.mysql.com/doc/refman/8.4/en/view-restrictions.html
The maximum number of tables that can be referenced in the definition of a view is 61. View processing is not optimized: It is not possible to create an index on a view. Indexes can be used for views processed using the merge algorithm. However, a ...
https://dev.mysql.com/doc/refman/8.4/en/views.html
Views are stored queries that when invoked produce a result set. The following discussion describes the syntax for creating and dropping views, and shows some examples of how to use them. Additional Resources You may find the MySQL User Forums ...