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https://dev.mysql.com/doc/refman/8.4/en/identifier-length.html
This applies to identifiers in table definitions and to identifiers stored in the grant tables in the mysql database. Values such as user name and host names in MySQL account names are strings rather than identifiers. The following table describes ...
https://dev.mysql.com/doc/refman/8.4/en/identifier-mapping.html
For the basic structure, MySQL represents each database as a directory in the data directory, and depending upon the storage engine, each table may be represented by one or more files in the appropriate database directory. MySQL encodes any ...
https://dev.mysql.com/doc/refman/8.4/en/index-extensions.html
EXPLAIN for the query produces this result: mysql> EXPLAIN SELECT COUNT(*) FROM t1 WHERE i1 = 3 AND d = '2000-01-01'\G *************************** 1. In this case, it can use the leftmost index prefix (d, i1) to produce a better execution plan: ...
https://dev.mysql.com/doc/refman/8.4/en/index-merge-optimization.html
In addition to using the optimizer_switch system variable to control optimizer use of the Index Merge algorithms session-wide, MySQL supports optimizer hints to influence the optimizer on a per-statement basis. The Index Merge access method ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-cached-indexes-table.html
N_CACHED_PAGES The total number of index pages cached in the InnoDB buffer pool for a specific index since MySQL Server last started. Examples This query returns the number of index pages cached in the InnoDB buffer pool for a specific index: mysql> ... The INNODB_CACHED_INDEXES table reports the number of index pages cached in the InnoDB buffer pool for each ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-datafiles-table.html
If a file-per-table tablespace is created in a location outside the MySQL data directory, the path value is a fully qualified directory path. Example mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_DATAFILES WHERE SPACE = 57\G ... The ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tables-table.html
This maximum value changes from 64 to 255 as of MySQL 9.1.0. Example mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TABLES WHERE TABLE_ID = 214\G *************************** 1. For related usage information and examples, see Section 17.15.3, ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-tablespaces-brief-table.html
If a file-per-table tablespace is created in a location outside the MySQL data directory, the path value is a fully qualified directory path. Example mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TABLESPACES_BRIEF WHERE SPACE = 7; ... The ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-temp-table-info-table.html
Example mysql> CREATE TEMPORARY TABLE t1 (c1 INT PRIMARY KEY) ENGINE=INNODB; mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO\G *************************** 1. The INNODB_TEMP_TABLE_INFO table provides information about user-created ...
https://dev.mysql.com/doc/refman/8.4/en/information-schema-innodb-virtual-table.html
The INNODB_VIRTUAL table provides metadata about InnoDB virtual generated columns and columns upon which virtual generated columns are based. A row appears in the INNODB_VIRTUAL table for each column upon which a virtual generated column is based.