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.
Syntax
The syntax goes like this:
sys.ps_is_thread_instrumented(in_connection_id)Where in_connection_id is the connection ID to check.
Example
Here’s an example to demonstrate:
SELECT sys.ps_is_thread_instrumented( 80 );Result:
YES
This shows that instrumentation for connection ID 80 is enabled.
Check the Current Connection
We can use the connection_id() function to check the current connection:
SELECT sys.ps_is_thread_instrumented( connection_id() );Result:
YES
This shows that instrumentation for the current connection is enabled.
Here’s the current connection ID:
SELECT connection_id();Result:
79
Non-Existent Connection ID
If the connection ID is unknown (or doesn’t exist), sys.ps_is_thread_instrumented() returns UNKNOWN:
SELECT sys.ps_is_thread_instrumented( 81 );Result:
UNKNOWN
NULL Connection ID
If the argument is NULL, then NULL is returned:
SELECT sys.ps_is_thread_instrumented( NULL );Result:
NULL
Passing the Wrong Number of Arguments
Passing the wrong number of arguments results in an error:
SELECT sys.ps_is_thread_instrumented( 79, 80 );Result:
ERROR 1318 (42000): Incorrect number of arguments for FUNCTION sys.ps_is_thread_instrumented; expected 1, got 2
The same applies when we don’t pass any arguments:
SELECT sys.ps_is_thread_instrumented( );Result:
ERROR 1318 (42000): Incorrect number of arguments for FUNCTION sys.ps_is_thread_instrumented; expected 1, got 0