system/Database/BaseConnection.php
public function callFunction(string $functionName, ...$params): bool
	{
		$driver = ($this->DBDriver === 'postgre' ? 'pg' : strtolower($this->DBDriver)) . '_';

		if (false === strpos($driver, $functionName))
		{
			$functionName = $driver . $functionName;
		}

		if (! function_exists($functionName))
		{
			if ($this->DBDebug)
			{
				throw new DatabaseException('This feature is not available for the database you are using.');
			}

			return false;
		}

		return $functionName(...$params);
	}
public function callFunction(string $functionName, ...$params): bool
	{
		$driver = ($this->DBDriver === 'postgre' ? 'pg' : strtolower($this->DBDriver)) . '_';

		if (false === strpos($driver, $functionName))
		{
			$functionName = $driver . $functionName;
		}

		if (! function_exists($functionName))
		{
			if ($this->DBDebug)
			{
				throw new DatabaseException('This feature is not available for the database you are using.');
			}

			return false;
		}

		return $functionName(...$params);
	}
This function enables you to call PHP database functions that are not natively included
in CodeIgniter, in a platform independent manner.

@param string $functionName
@param array  ...$params

@return boolean
@throws DatabaseException