[Monetdb-developers] trying to use monetdb pathfinder

Ying Zhang Y.Zhang at cwi.nl
Thu Feb 8 10:50:39 CET 2007


On Mon, Feb 05, 2007 at 09:08:59PM +0100, Martijn Faassen wrote:
> Hi there,
> 
> Just downloaded and installed the new release. Compiling and installing 
> on my system went off without a hitch, my compliments.
> 
> I've been trying to use pathfinder's xquery's support and I ran into 
> some snags. It may be something I do wrong, but I'll ask anyway.
> 
> First, I was testing the xquery support. I tried to shred a document 
> like this:
> 
> shred_doc('/home/faassen/xml/shaks/hamlet.xml', 'hamlet')
> 
> and then to refer to this document from an xquery like this:
> 
> doc('hamlet')//FM
> 
> I get the following error:
> 
> MAPI  = monetdb at localhost:50000
> QUERY = doc('hamlet')//FM
> ERROR = !ERROR: [shred_url]: 1 times inserted nil due to errors at 
> tuples 0 at 0.
>          !ERROR: [shred_url]: first error was:
>          !ERROR: shred: cannot stat `hamlet': No such file or directory
>          !ERROR: CMDshred_url: operation failed.
>          !ERROR: interpret_params: leftfetchjoin(param 2): evaluation error.
> 
> Hinted by the 'cannot stat', I tried the following:
> 

Hi Martijn,

It seems that the "shred_doc" operation did not succeed.  Is the above
line with "shred_doc" a literal copy of what you entered in Mserver?
Then you need to add the ';' sign at the end of the line:

    shred_doc('/home/faassen/xml/shaks/hamlet.xml', 'hamlet');

Note that a MIL statement needs to be terminated by a ';' sign.
Otherwise, Mserver will wait for more input.

If "shred_doc" succeeded, you should get some information like the
following:

MonetDB>shred_doc("/ufs/zhang/xrpcdemo/hello.xml", "hello.xml");
# Elapsed time = 010ms 671us [002ms 667us/node]
# Shredded 1 XML document (hello.xml), total time after commit=0.065s


Regards,

Jennie






> doc('/home/faassen/xml/shaks/hamlet.xml')//FM
> 
> and this gets a step further (still wondering why the former didn't 
> work, though):
> 
> MAPI  = monetdb at localhost:50000
> QUERY = doc('/home/faassen/xml/shaks/hamlet.xml')//FM
> ERROR = !ERROR: I/O warning : failed to load external entity "play.dtd"
>          !ERROR: [shred_url]: 1 times inserted nil due to errors at 
> tuples 0 at 0.
>          !ERROR: [shred_url]: first error was:
>          !ERROR: shred_external_subset: WARNING: xmlParseDTD("play.dtd") 
> FAILED, NO ID/IDREF QUERIES
>          !ERROR: shred_external_subset: NOTE   : maybe using absolute 
> filenames works, sorry!
>          !ERROR: CMDshred_url: operation failed.
>          !ERROR: interpret_params: leftfetchjoin(param 2): evaluation error.
> 
> The play.dtd is in the directory next to 'hamlet.xml', so don't know why 
> that doesn't work either.
> 
> So, I made a new hamlet2.xml removing the dtd reference. I don't need 
> dtd support anyway, but it'd be nice if it could parse documents with 
> dtds, of course. Now, it works.
> 
> Next, I was trying out the xquery update support. Not hindered by any 
> knowledge on how it works, I went to the referenced W3C document and 
> adapted the first insert statement I saw there into this:
> 
> do insert <year>2005</year>
>    after fn:doc('/home/faassen/xml/shaks/hamlet2.xml')/PLAY/TITLE
> 
> This however gives me an error message I do not understand:
> 
> MAPI  = monetdb at localhost:50000
> QUERY = do insert <year>2005</year>
>            after fn:doc('/home/faassen/xml/shaks/hamlet2.xml')/PLAY/TITLE
> ERROR = !type error: no variant of function upd:insertAfter accepts the 
> given argument type(s): element TITLE { item* }*; (node* | node)*
>          !type error: maybe you meant:
>          !type error:   upd:insertAfter (node, node*) as stmt
>          !type error: illegal arguments for function upd:insertAfter
> 
> What am I doing wrong there?
> 
> Regards,
> 
> Martijn
> 
> 
> 
> 
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