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https://dev.mysql.com/doc/refman/5.7/en/enum.html
An ENUM is a string object with a value chosen from a list of permitted values that are enumerated explicitly in the column specification at table creation time. The ENUM type has these advantages: Compact data storage in situations where a column ...See Section 11.3.1, “String Data Type Syntax” for ENUM type syntax and length ...
https://dev.mysql.com/doc/refman/5.7/en/innodb-memcached-porting-mysql.html
If there is a short numeric primary key column in an InnoDB table, use it as the unique lookup key for memcached by converting the integer to a string value. In any query that performs arithmetic using column values, use the CAST() function to ...
https://dev.mysql.com/doc/refman/5.7/en/order-by-optimization.html
The index may also be used even if the ORDER BY does not match the index exactly, as long as all unused portions of the index and all extra ORDER BY columns are constants in the WHERE clause. If the index does not contain all columns accessed by the ... This section describes when MySQL can use an index to satisfy an ORDER BY clause, the filesort operation used when an index cannot be used, and execution plan information available from the optimizer about ORDER ...
https://dev.mysql.com/doc/refman/5.7/en/performance-schema-statement-summary-tables.html
Each statement summary table has one or more grouping columns to indicate how the table aggregates events. Event names refer to names of event instruments in the setup_instruments table: events_statements_summary_by_account_by_event_name has ... The ...
https://dev.mysql.com/doc/refman/5.7/en/grant.html
Database, table, column, and routine names can be up to 64 characters. Object Quoting Guidelines Several objects within GRANT statements are subject to quoting, although quoting is optional in many cases: Account, database, table, column, and ...
https://dev.mysql.com/doc/refman/5.7/en/create-table-ndb-comment-options.html
NDB_COLUMN Options NDB_TABLE Options It is possible to set a number of options specific to NDB Cluster in the table comment or column comments of an NDB table. NDB_COLUMN can be used in a column comment to set the size of the blob parts table ...
https://dev.mysql.com/doc/refman/5.7/en/union.html
Selected columns listed in corresponding positions of each SELECT statement should have the same data type. For example, the first column selected by the first statement should have the same type as the first column selected by the other statements.
https://dev.mysql.com/doc/refman/5.7/en/data-size.html
You can get better performance for a table and minimize storage space by using the techniques listed here: Table Columns Row Format Indexes Joins Normalization Table Columns Use the most efficient (smallest) data types possible. MEDIUMINT is often a ... Design your tables to minimize their space on the ...
https://dev.mysql.com/doc/refman/5.7/en/faqs-cjk.html
You can obtain this information for a column column_name in the table table_name using the following query: SELECT HEX(column_name) FROM table_name; 3F is the encoding for the ? character; this means that ? is the character actually stored in the ...
https://dev.mysql.com/doc/refman/5.7/en/partitioning-range.html
While the examples work as shown for purposes of the present discussion, you should keep in mind that tables are extremely likely in practice to have primary keys, unique keys, or both, and that allowable choices for partitioning columns depend on ... A table that is partitioned by range is partitioned in such a way that each partition contains rows for which the partitioning expression value lies within a given ...