In MySQL, we can use the sys.ps_is_instrument_default_enabled() function to check whether a given Performance Schema instrument is enabled by default.
The function returns YES or NO, depending on whether the instrument is enabled by default.
MySQL
Create a CHECK Constraint in MySQL
As of MySQL 8.0.16, we can create CHECK constraints in MySQL.
A CHECK constraint is a type of integrity constraint. It specifies a search condition to check the value being entered into a row. If the value being entered violates the CHECK constraint, then the result of the search condition is FALSE and an error occurs (unless the IGNORE clause is used in the SQL statement, in which case a warning is reported and the offending row is skipped).
The ability to create CHECK constraints was introduced in MySQL 8.0.16. Prior to version 8.0.16, MySQL actually allowed a limited version of CHECK constraint syntax, but it was completely ignored (no CHECK constraint was created or evaluated).
Understanding the sys.ps_is_instrument_default_timed() Function in MySQL
In MySQL, we can use the sys.ps_is_instrument_default_timed() function to check whether a given Performance Schema instrument is timed by default.
The function returns YES or NO, depending on whether the instrument is timed by default.
Understanding the sys.ps_is_thread_instrumented() Function in MySQL
In MySQL, we can use the sys.ps_is_thread_instrumented() function to check whether Performance Schema instrumentation for a given connection ID is enabled.
The function returns YES or NO, depending on whether the instrumentation is enabled for the given connection. It can also return UNKNOWN if the connection ID is unknown, and NULL if the connection ID is NULL.
Understanding the sys.version_patch() Function in MySQL
In MySQL, we can use the sys.version_patch() function to return the patch release version of the MySQL server.
For example, if we’re using MySQL 8.0.33, sys.version_patch() returns 33.
Understanding the sys.version_minor() Function in MySQL
In MySQL, we can use the sys.version_minor() function to return the minor release version of the MySQL server.
Understanding the sys.version_major() Function in MySQL
In MySQL, we can use the sys.version_major() function to return the major release version of the MySQL server.
Understanding the PS_CURRENT_THREAD_ID() Function in MySQL
In MySQL, we can use the PS_CURRENT_THREAD_ID() function to get the Performance Schema thread ID assigned to the current connection.
The PS_CURRENT_THREAD_ID() function was added in MySQL 8.0.16, and it does the same thing as PS_THREAD_ID(CONNECTION_ID()).
Understanding the FORMAT_PICO_TIME() Function in MySQL
In MySQL, format_pico_time() is a Performance Schema function that converts a numeric Performance Schema latency or wait time in picoseconds into a human-readable format. It returns a string consisting of a value and a units indicator.
MySQL DEFAULT() Function Explained
In MySQL, the DEFAULT() function returns the default value for a given column in the database.
If the column doesn’t have a default value, an error is returned.