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.
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.
In MySQL, we can use the sys.version_minor() function to return the minor release version of the MySQL server.
In MySQL, we can use the sys.version_major() function to return the major release version of the MySQL server.
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()).
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.
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.
Continue readingThe following table contains a full list of the aggregate functions in MySQL.
Continue readingIn MySQL, the GROUPING() function allows us to identity which rows have been generated by the WITH ROLLUP modifier of the GROUP BY clause.
By default, WITH ROLLUP outputs NULL as the value that represents all aggregate values. By this, I mean it doesn’t provide us with a nice easy to read label. It simply outputs NULL. This makes it more difficult for us to distinguish between normal rows and super aggregate rows that were generated by WITH ROLLUP.
In MySQL, list_add() is a system function that adds a value to a comma-separated list of values and returns the result.
So it’s a handy function that allows us to append a value to a list.
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