On Sunday 28 October 2007 01:28, Nikola Smolenski wrote: > Would it be possible to add some user defined functions to MySQL servers? > I'm having in mind Levenshtein distance: > http://empyrean.lib.ndsu.nodak.edu/~nem/mysql/udf/dludf.cgi?ckey=28
Given that there was no response to this, perhaps I should be a bit less terse. A user defined function (UDF) is a function added to MySQL by an external library. It is used as any other MySQL function. You can read more at http://dev.mysql.com/doc/refman/5.0/en/adding-functions.html and http://dev.mysql.com/doc/refman/5.0/en/create-function.html . I can (hopefully) compile the library, but root access is needed to add the function to MySQL. A function which I would like to have is Levenshtein distance. This function can tell how similar two strings are, similar to SOUNDEX() function, but the latter is limited to English language, and even in it it Levenshtein could perform better. You can read more at http://en.wikipedia.org/wiki/Levenshtein_distance . I see two very interesting applications for it: finding articles with similar titles, and measuring amount of a contribution. The first is obviously useful to locate missing redirects, duplicate articles and similar problems, and could later even be included in MediaWiki to assist searching, and the second could be used to highlight significant edits (edits which change a lot of text in an article may still have make small difference in text size) albeit this probably wouldn't be useful on the Toolserver. To my knowledge, there should be no performance issues (MySQL shouldn't work slower with UDFs installed), and I have not found about any security issues. If someone thinks that another UDF might be useful, see a list of them at http://empyrean.lib.ndsu.nodak.edu/~nem/mysql/udf/ _______________________________________________ Toolserver-l mailing list [email protected] http://lists.wikimedia.org/mailman/listinfo/toolserver-l
