Re: [xml] Streaming XPATH and xmlPatternCompile

["Aron Stansvik" <elvstone gmail com>]

2007/10/25, Daniel Veillard <veillard redhat com>:
> On Thu, Oct 25, 2007 at 01:58:58PM +0200, Aron Stansvik wrote:
> > 2007/10/17, s kum <boha4100 yahoo com>:
> > > Hi,
> > >
> > > We are looking for a way to process XPATH expressions on very large xml
> > > documents. Because of the size of the documents, we like to use stream
> > > processing – something along the lines of XPathReader from MS. Searching the
> > > archive, we found we could possibly use xmlPatternCompile along with
> > > xmlTextReader* APIs to do the same. We are getting compilation errors on
> > > several XPATH expressions when we do this.
> > >
> > > Are there limitations to XPATH expressions supported by xmlPatternCompile ?
> > > If so, what are those? Can it support author[first-name = "Bob"] and
> > > degree[ from != "Harvard"] kind of conditional expressions ?
>
>   Conditionals are not supported
> It is restricted to IDC patterns from XML Schemas
> which are normal XPath 1.0 paths I think
>    [5]    Path    ::=    ('.//')? ( Step '/' )* ( Step | '@' NameTest )
> basically you can use it as a selector to select just the
> nodes you are interested into. But if you have 2 millions records
> with exactly the same structure it won't help that much.
>
> > Seems to work just fine here:
> [...]
> > [astan franz ~]$ xmllint --shell test.xml
> > / > xpath //bar[baz = 'aaa']
>
>   Well actually --shell is not streaming it uses the normal XPath
> document tree :-)

Ah. Duh.

Aron