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https://dev.mysql.com/doc/refman/8.0/en/derived-table-optimization.html
The optimizer handles derived tables, view references, and common table expressions the same way: It avoids unnecessary materialization whenever possible, which enables pushing down conditions from the outer query to derived tables and produces more ...The outer query does not specify DISTINCT, HAVING, or ORDER ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-stage-tables.html
During execution of an ALTER TABLE statement, the stage/sql/copy to tmp table stage is used, and this stage can execute potentially for a long time, depending on the size of the data to copy. To enable the instrument and the relevant consumers, ...
https://dev.mysql.com/doc/refman/8.0/en/myisamchk-table-info.html
To obtain a description of a MyISAM table or statistics about it, use the commands shown here. myisamchk -d tbl_name Runs myisamchk in “describe mode” to produce a description of your table. If you start the MySQL server with external locking ...The output from these commands is explained later in this ...
https://dev.mysql.com/doc/refman/8.0/en/create-tablespace.html
TABLESPACE [=] tablespace_name or ALTER TABLE tbl_name TABLESPACE [=] tablespace_name to add tables to the tablespace. Additional data files may be added to the tablespace by using the ALTER TABLESPACE statement (see Section 15.1.10, “ALTER ...The ...
https://dev.mysql.com/doc/refman/8.0/en/log-destinations.html
CREATE TABLE, ALTER TABLE, and DROP TABLE are valid operations on a log table. For ALTER TABLE and DROP TABLE, the log table cannot be in use and must be disabled, as described later. The log tables can be altered to use the MyISAM storage engine.
https://dev.mysql.com/doc/refman/8.0/en/server-options.html
It also causes OPTIMIZE TABLE to be mapped to ALTER TABLE for storage engines for which OPTIMIZE TABLE is not supported. It is ignored and has no effect on the operation of ALTER INSTANCE RELOAD TLS at runtime. For example, you can use ... When you ...
https://dev.mysql.com/doc/refman/8.0/en/derived-tables.html
Alternatively, tbl_name may be followed by a parenthesized list of names for the derived table columns: SELECT ... For information about lateral derived tables preceded by the LATERAL keyword, see Section 15.2.15.9, “Lateral Derived Tables”. A ...This does not work: SELECT AVG(SUM(column1)) FROM t1 GROUP BY column1; However, this query provides the desired information: SELECT AVG(sum_column1) FROM (SELECT SUM(column1) AS sum_column1 FROM t1 GROUP BY column1) AS t1; Notice that the column name used within the subquery (sum_column1) is recognized in the outer ...
https://dev.mysql.com/doc/refman/8.0/en/with.html
A common table expression (CTE) is a named temporary result set that exists within the scope of a single statement and that can be referred to later within that statement, possibly multiple times. Common Table Expressions Recursive Common Table ...
https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-limitations-syntax.html
Trying either to create a temporary table that uses the NDB storage engine or to alter an existing temporary table to use NDB fails with the error Table storage engine 'ndbcluster' does not support the create option 'TEMPORARY'. CREATE TABLE and ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-summary-tables.html
Summary tables provide aggregated information for terminated events over time. The tables in this group summarize event data in different ways. Each summary table has grouping columns that determine how to group the data to be aggregated, and ...