[MarkLogic Dev General] Type safe data and referencing questions

[Mark Waschkowski]

OK great, thanks for the information Danny.

I'm a bit concerned about the type safety issue (#1) not because I'm
worried about the data being stored correctly, but because a
conversion might have to be carried out many many time during an
evaluation. I may be repeating the question here, but do you have any
idea of how the above use case would work with 1M+ rows of data. Seems
to me that converting some date text 2M+ times (twice per record in
this case) would have an adverse effect on a query, no? Likewise
converting when wanting to order a larger data set by date?

Really appreciate the feedback.

Mark

On Jan 14, 2008 8:12 PM, Danny Sokolsky <dsokolsky at marklogic.com> wrote:
> Hi Mark,
>
> I will take a stab at your questions.
>
> 1) You do not need a schema to use typed data.  A schema will make it so
> Mark Logic treats an element or attribute as its defined type without an
> explicit cast, but you can always add an explicit cast (like the
> use-case example) to make sure XQuery treats a value as a certain type
> (with or without a schema).  The schema just makes that a little easier.
> There might be some performance advantage to using a schema, but I don't
> think it will be that big.  It is worth trying though, as this might
> depend somewhat on your content.  The real performance advantage will
> come from creating range indexes on elements or attributes you will use
> in comparisons.  Schemas can also help you ensure that your data is in
> the correct format when you load it, as Mark Logic will throw an
> exception if it cannot cast content in an element or attribute to the
> type specified in the schema.
>
> 2) You could put the referencing information in the properties document.
> The default conversion application in CPF does this, for example, to
> keep track of the original documents and various converted documents.
>
> 3) There are no foreign key constraints built in.  I think any best
> practices would depend on what you are trying to do.  Two approaches
> that tend to work well are to a) put the constraining items in the same
> document and/or b) use the properties document corresponding to a
> document to store information about what is in the document.
>
> -Danny
>
>
> -----Original Message-----
> From: general-bounces at developer.marklogic.com
> [mailto:general-bounces at developer.marklogic.com] On Behalf Of Mark
> Waschkowski
> Sent: Monday, January 14, 2008 1:25 PM
> To: general at developer.marklogic.com
> Subject: [MarkLogic Dev General] Type safe data and referencing
> questions
>
> Hi,
>
> Have been using Marklogic for a while now and haven't seen answers to
> the below questions yet, anyone know of an answer or two?
>
> 1) Type safe data -  I'm concerned with retrieval of typed data,
> especially for date information. The only way to store typed data is
> through the use of a schema right? I can't specify the type of data on
> a per element basis, correct? ie. <person> <birthday
> xs:date>01-01-1970</birthday></person>
>
> As well, I noticed the below query in the use case examples:
>
>  let $item := doc("items.xml")//item_tuple
>               [end_date >= xs:date("1999-03-01")
>                and
>                end_date <= xs:date("1999-03-31")]
>  return
>  <item_count>
>  {
>    count($item)
>  }
>  </item_count>
>
> Is there a schema behind the loaded data or are the examples un-type
> safe? Should I just not worry about type safety and convert the data
> values to the type I need when querying? If so, won't that be a
> performance issue?
>
> 2) Referencing - what is the (if there is one) best practice approach
> to reference documents together?
> ie. Document A and Document B should both refer to Document C
>
> 3) Foreign key constraints - is this supported at all in some fashion?
> If not, any approaches to suggest?
>
> Thanks in advance for any and all suggestions!
>
> Mark
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