Re: XML databases [ was: S.O.D.A. database Query API - call for comments ]

On Sat, 21 Jul 2001 23:24:42 GMT, Philip Lijnzaad <lijnzaad_at_ebi.ac.uk> wrote:

>Not necessarily; gunzip unzips things by blocks (e.g. you can concat gzipped
>files using cat (1)).

But random access is still hard without having additional indexing.

>And a dedicated encoding could even be more
>intelligent than this.

Dedicated XML compressors exist:

http://www.xmls.com/products/xmlzip/xmlzip.html
http://www.research.att.com/sw/tools/xmill/
http://www.cs.cornell.edu/People/jcheney/xmlppm/xmlppm.html

They typically split an XML document into its different element types and compress all elements of one type independent of the elements of other types. This will lead to better compression ratios but will make random access even harder because the subelements of a more complex element will have to be assembled from different compressed streams.

BTW, do you guys have to have your DB discussion in so many newsgroups at the same time? It seems to be offtopic in comp.lang.java.programmer while it's also posted to comp.lang.java.databases. I didn't set a f'up2 because I don't know where the discussion is most appropriate.

Regards,
Marco

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