Golden Phrases assume that every line of log file can contain one referer from search phrase. Therefore, it try to apply the search engine specific pattern for every line of log files. And if line has an string of chars matching with pattern it assume that this line has referring URL from search engine and try to extract the search phrase and other accompanying information from this line.
Golden Phrases do not make any assumptions of a format of a files, it's independent from format of log files, i.e. can properly handle log files with almost any format. Also it's very fast and can understand the compressed log files.