In MySQL, the sys.format_statement() system function reduces the length of a given string/SQL statement to the length stored in the statement_truncate_len configuration option.
This function can be handy for truncating potentially long SQL statements retrieved from Performance Schema tables into a more suitable length (64 characters by default).
In MySQL, we can use the PS_THREAD_ID() function to get the Performance Schema thread ID assigned to a given connection ID. This can be useful whenever we use a function that takes the thread ID as its parameter, but we only know the connection ID.
If no thread ID exists for the connection, then NULL is returned.
The built-in PS_THREAD_ID() function does the same thing as the now deprecated sys.ps_thread_id() function. Therefore, we can call the function without needing to qualify it with sys or making sys our current schema.
Behind every well-structured and organised SQL database lies a treasure trove of information called metadata. Metadata is data that provides information about other data. In relational database management systems, this metadata can typically include information like the names of databases, tables, columns, the data type of a column, access privileges, and much more.
The SQL standard provides a collection of tables/views that allow us to view metadata about the objects in the database. The SQL standard refers to this as the information schema and calls it INFORMATION_SCHEMA.
In MySQL, the sys.format_path() function is a stored function in the sys schema. It accepts a path name, and returns the modified path name after replacing subpaths that match the values of certain system variables.
So we can use the function to dynamically replace part or all of our path with a system variable that matches that path segment.
In MySQL, the sys.extract_table_from_file_name() function is a stored function in the sys schema.
It accepts a path name, and returns the path component that represents the table name.
In MySQL, we can use the sys.ps_is_account_enabled() function to check whether Performance Schema instrumentation for a given account is enabled.
The function returns YES or NO, depending on whether or not the instrumentation for the given account is enabled.
In MySQL, the sys.ps_thread_account() function returns the account associated with a given thread ID. It returns the account in the form user_name@host_name.
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.
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.
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.