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SHOW VARIABLES LIKE "%wait%" Result: 28800 SET @@GLOBAL.wait_timeout=300 SHOW GLOBAL VARIABLES LIKE "%wait%" Result: 300 SHOW SESSION VARIABLES LIKE "%wait%" Result:28800 I am confused by the results. Why does the last query give Result:28800 ?
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MySQL has its wait_timeout variable default value set to 28800 seconds (8 hours).
To run these commands, first we need to login to MySql server. We can check the current values of the wait_timeout variable using below commands. SHOW SESSION VARIABLES LIKE “%wait_timeout%”; or SHOW SESSION VARIABLES LIKE “wait_timeout”; Default wait_timeout value is 28800 seconds.
A session variable is a user-defined variable (not a server option) that starts with @, does not require declaration, can be used in any SQL query or statement, not visible to other sessions, and exists until the end of the current session.
Your session status are set once you start a session, and by default, take the current GLOBAL value.
If you disconnected after you did SET @@GLOBAL.wait_timeout=300, then subsequently reconnected, you'd see
SHOW SESSION VARIABLES LIKE "%wait%"; Result: 300 Similarly, at any time, if you did
mysql> SET session wait_timeout=300; You'd get
mysql> SHOW SESSION VARIABLES LIKE 'wait_timeout'; +---------------+-------+ | Variable_name | Value | +---------------+-------+ | wait_timeout | 300 | +---------------+-------+ If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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