https://dev.mysql.com/processlist-table.html
For the SHOW PROCESSLIST statement, the value of STATE is NULL. INFO The statement the thread is executing, or NULL if it is not executing any statement. The PROCESSLIST table provides information about which threads are running. This is the same ...
https://dev.mysql.com/row-constructor-optimization.html
row *************************** id: 1 select_type: SIMPLE table: t1 partitions: NULL type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: const rows: 3 filtered: 100.00 Extra: Using where In such cases, rewriting the row constructor ...For ...
https://dev.mysql.com/set.html
For example, a column specified as SET('one', 'two') NOT NULL can have any of these values: '' 'one' 'two' 'one,two' A SET column can have a maximum of 64 distinct members. A SET is a string object that can have zero or more values, each of which ...
https://dev.mysql.com/spatial-geohash-functions.html
Unless otherwise specified, functions in this section handle their arguments as follows: If any argument is NULL, the return value is NULL. Geohash is a system for encoding latitude and longitude coordinates of arbitrary precision into a text ...
https://dev.mysql.com/string-type-syntax.html
CHAR(0) is also quite nice when you need a column that can take only two values: A column that is defined as CHAR(0) NULL occupies only one bit and can take only the values NULL and '' (the empty string). A string object that can have only one ...
https://dev.mysql.com/sys-innodb-lock-waits.html
locked_table_partition The name of the locked partition, if any; NULL otherwise. locked_table_subpartition The name of the locked subpartition, if any; NULL otherwise. This field reports NULL if the session that issued the blocking query becomes ...
https://dev.mysql.com/sys-ps-is-consumer-enabled.html
Returns YES or NO to indicate whether a given Performance Schema consumer is enabled, or NULL if the argument is NULL. (Prior to MySQL 8.0.18, the function returns NULL if the argument is not a valid consumer name.) This function accounts for the ...If the argument is not a valid consumer name, an error ...
https://dev.mysql.com/where-optimization.html
This is also done for any NOT NULL expression when used with only one table. A table that is used with a WHERE clause on a PRIMARY KEY or a UNIQUE index, where all index parts are compared to constant expressions and are defined as NOT NULL. This ...
https://dev.mysql.com/writing-daemon-plugins.html
A daemon plugin is a simple type of plugin used for code that should be run by the server but that does not communicate with it. This section describes how to write a daemon server plugin, using the example plugin found in the plugin/daemon_example ...
https://dev.mysql.com/writing-keyring-plugins.html
The general descriptor also refers to keyring_system_variables, a structure that exposes a system variable to the SHOW VARIABLES statement: static struct st_mysql_sys_var *keyring_system_variables[]= { MYSQL_SYSVAR(data), NULL }; The keyring_init ...
