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From Jacques Nadeau <jacq...@dremio.com>
Subject Re: Apache Drill
Date Sun, 18 Oct 2015 22:26:27 GMT
I actually generating thing this is a special version of object promotion.
Steven is already working on solving the same problem where it exists when
we have the JSON file:

{"item":1}
{"item":[2,3]}

The main difference isn't until we see the "3" value in XML that we need to
promote the "2" value to be the first element in an array. In Drill this is
simply a value copy (not something that is currently exposed in
ComplexWriter but exists at the vector level already). We could also do the
promotion with lookahead and a markable/rewindable event stream.

In general though, I agree with Julian. Let's get a basic reader working
first.

Does someone want to create a JIRA and propose a basic design. I'm more
than happy to help people through the format plugin definitions as
necessary since documentation there is lean.



--
Jacques Nadeau
CTO and Co-Founder, Dremio

On Sun, Oct 18, 2015 at 11:24 AM, Ted Dunning <ted.dunning@gmail.com> wrote:

> Kasper,
>
> This might work.
>
> One issue that I see is that Metamodel seems to take a very XML centric
> view of things while Drill takes a pretty JSON view of things.
>
> The point at which I think that this might cause problems is that Drill
> currently has troubles when it sees a records like
>
> <record><item>1</item></record>
> <record><item>2</item><item>3</item></record>
>
> This is fine as far as XML is concerned, but if you think about it in terms
> of JSON, it is probably best to view these records as
>
> {"item":[1]}
> {"item":[2,3]}
>
> Unfortunately, from the first record, there is no way to tell that it
> should not be viewed as
>
> {"item":1}
>
> Do you have a suggestion that would help with this?
>
>
> On Sun, Oct 18, 2015 at 8:41 AM, Kasper Sørensen <
> i.am.kasper.sorensen@gmail.com> wrote:
>
> > Hi there,
> >
> > Sorry for barging in, but maybe this is a place where Drill and MetaModel
> > could benefit from each other? We've considered that before at least ...
> >
> > MetaModel already has support for both DOM and SAX based XML querying.
> They
> > basically inherit some characteristics from DOM and SAX respectively:
> >
> >  - In the DOM variant we can infer a schema and all the user has to do is
> > select a XML file/resource anywhere.
> >  - In the SAX variant the user has to specify which paths in the XML
> > document should represent logical "tables" and what paths represent their
> > columns.
> >
> > See [1] for more info. Hope this might be of interest to integrate into
> > Drill?
> >
> > Best regards,
> > Kasper Sørensen (from the MetaModel project)
> >
> > [1] http://wiki.apache.org/metamodel/examples/XmlTableMapping
> >
> > 2015-10-18 0:35 GMT+02:00 Magnus Pierre <mpierre@maprtech.com>:
> >
> > > Well, very few lines of code imho. And simple. Been able to parse
> pretty
> > > deep structures with no issues so far. Performance? 10-15 5mb xml's in
> > less
> > > than a second on my laptop but then I run it using Storm with some
> > > parallelism in place. Don't know if it's good or bad. I'll share the
> code
> > > next time I use computer. You don't need to use it, but it works at
> > least.
> > >
> > > /M
> > > Den 17 okt 2015 10:43 em skrev "Matt Burgess" <mattyb149@gmail.com>:
> > >
> > > > If the converter is clean and performant then I'm sure the community
> > > > (including me) is interested :)
> > > >
> > > > However I wonder if Drill can afford to add a translation layer
> between
> > > > data formats, could we be better served with similar parsing in Drill
> > for
> > > > XML as we do for JSON, or can it be pushed down far enough (to the
> > > parser)
> > > > to not make a noticeable difference (which is what I think Julian is
> > > > implying)?
> > > >
> > > > Sent from my iPhone
> > > >
> > > > > On Oct 17, 2015, at 1:41 PM, Magnus Pierre <mpierre@maprtech.com>
> > > wrote:
> > > > >
> > > > > Hello,
> > > > >
> > > > > Just wrote a simple sax implementation that converts xml to json
> and
> > > that
> > > > > is able to deal with decently complex xml's, that I currently use
> in
> > > > Storm.
> > > > > Takes attributes, and everything.
> > > > >
> > > > > I can share it with the community if interesting.
> > > > >
> > > > > /Magnus
> > > > > Den 17 okt 2015 7:02 em skrev "Julian Hyde" <julian@hydromatic.net
> >:
> > > > >
> > > > >> Seems to me the biggest problem is to make drill understand the
> > nested
> > > > >> structure of an xml document. That work has been done for json,
so
> > > let's
> > > > >> build on it. Suppose there was a translator that converted xml
to
> > json
> > > > >> (adding attributes for things that json lacks, such as namespaces,
> > > text,
> > > > >> element tags). Drill knows how to handle json, even if it is
a bit
> > > > verbose.
> > > > >> The translator could be applied on the fly.
> > > > >>
> > > > >> Julian
> > > > >>
> > > > >>
> > > > >>
> > > > >> Sent from my iPad
> > > > >>>> On Oct 16, 2015, at 2:31 PM, Stefán Baxter <
> > > stefan@activitystream.com
> > > > >
> > > > >>> wrote:
> > > > >>>
> > > > >>> Hi,
> > > > >>>
> > > > >>> It's not possible but there has been some talk here about
> > supporting
> > > > it.
> > > > >>> If I remember correctly it's rather complicated and not really
> > > > feasible.
> > > > >>> (I'm just a newbie so don't take my words for it)
> > > > >>>
> > > > >>>
> > > > >>> Regards,
> > > > >>> -Stefan
> > > > >>>
> > > > >>> On Fri, Oct 16, 2015 at 8:54 PM, Daniel Ajo <
> > > > Daniel.Ajo@abarcahealth.com
> > > > >>>
> > > > >>> wrote:
> > > > >>>
> > > > >>>> Hey there,
> > > > >>>>
> > > > >>>> I was wondering if it is possible to query XML files
using
> Apache
> > > > Drill?
> > > > >>>>
> > > > >>>> I see there are several formats, and maybe it would work
using
> an
> > > > xpath
> > > > >>>> query of some sorts, but just wondering if it would work
to
> > directly
> > > > >> query
> > > > >>>> it using some sort of plug-in.
> > > > >>>>
> > > > >>>> Well, let me know,
> > > > >>>>
> > > > >>>> Daniel Ajo
> > > > >>>> *********************************************************
> > > > >> CONFIDENTIALITY
> > > > >>>> NOTE: This electronic transmission contains information
> belonging
> > to
> > > > >> Abarca
> > > > >>>> Health LLC, which is confidential or legally privileged.
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> > > > >>>> intended recipient, please immediately advise the sender
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> >
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