xml for caching

[kante]

Is it a good idea to produce xml files after fetching results form a MySQL query
in order to improve response performances?

pseudo code

if file xml exists and filetime of xml file is not too old
return xml file
else
run mysql query
gen xml from resultset
write xmlfile
return newly created xml file

will this approach improve performances? or a normal LAMP environment is already "strong" enough to execute the same query many times in a second without affecting response performances?

thanks...

[dagon]

i wouldn't bother, the MySQL query cache does that already. I use to do a lot of caching but all the speeds have caught up so its generally not an issue. Of course there will always be specific case where it is a good idea

[NogDog]

If the XML is what you'll be outputting to the client, it might not hurt; but if you're going to use it simply as a data source which you'll then have to parse, the database query might well be faster, especially if the DB is properly designed and indexed.

[kante]

thanks for the answer... u confirmed me what I was thinking too.

I'm also thinking, is it possible in the case i still use chaching on xml , since i have to rewrite quite sometimes the xml file that someone will get a 404 error or something similar ...while PHP is rewriting the file?

i know writing time it is a fraction of second... but maybe...

or servers are smart enough to always be ready to answer the file?

[NogDog]

You might want to look at something like PEAR::Cache_Lite to handle all the details, including file locking.