PostgreSQL has a pg_input_error_info() function that allows us to see the error details that would be returned if we were to pass an invalid value for the specified data type.
Basically it tests whether the given string is valid input for the specified data type. If invalid, it returns the details of the error that would have been thrown. If valid, the result is null.
In PostgreSQL, the pg_input_is_valid() function tests whether the given string is valid input for the specified data type.
It returns a boolean value of either true or false.
This function only works if the data type’s input function has been updated to report invalid input as a “soft” error.
Continue readingIn MySQL, we can use the sys.ps_is_consumer_enabled() function to check whether a given Performance Schema consumer is enabled.
The function returns YES or NO, depending on whether or not the specified Performance Schema consumer is enabled. It returns NULL if the argument is NULL.
In MySQL, we can use the sys.sys_get_config() function to get a configuration option value from the sys_config table.
In MySQL, we can use the sys.quote_identifier() function to quote a string to produce a result that can be used as an identifier in a SQL statement.
The string is returned enclosed by backticks (`), with each instance of a backtick doubled.
This function can be handy when a value to be used as an identifier is a reserved word or contains backtick characters.
Continue readingIn MySQL, the sys.ps_thread_stack() function returns a JSON formatted stack of all statements, stages, and events within the Performance Schema for a given thread ID.
In MySQL, the sys.extract_schema_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 schema name.
This enables us to get the schema from a given file path.
Continue readingIn 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).
Continue readingIn 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.
Continue readingIn 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.
Continue reading