Faron,
Ideally, your data will use the "X[tensible" feature of XML to handle new tags.
Your data structure is a kind of meta-xml where the XML generically describes
XML:
<tagList>
<dateTag name="approved">20110101</dateTag>
<stringTag name="color">Gold</stringTag>
Might be more simply be represented as
<tagList>
<approved>20110101</approved>
<color>ABC</color >
This approach could not work in a relational DB, because you would need new
columns for every new key, but it's fine to add new XML elements in most
contexts. You will need to add range indexes for each custom field, but they
will only "reindex" documents that contain the fields in question.
There are other possible approaches, but clean, simple data modeling is ideal
if you can manage it.
Yours,
Damon
From:
[email protected]<mailto:[email protected]>
[mailto:[email protected]]<mailto:[mailto:[email protected]]>
On Behalf Of Fullbright, Faron
Sent: Wednesday, April 25, 2012 10:04 AM
To: '[email protected]'
Subject: [MarkLogic Dev General] Difficulty modeling our data in MarkLogic
We are evaluating the potential to use MarkLogic for indexing and storage of
content and have come across a use case that doesn't seem to map well to the
MarkLogic indexing model.
Just wanted to describe the data model we are using (or at least that section
of it that applies to this case), and see if we're potentially overlooking
something.
Our primary requirement for indexing revolves around custom tags that we allow
clients to associate with objects. These custom tags are name/value pairs, and
the values can have various types (string, date, datetime, real, int, etc.).
We need to be able to support fast range queries (that account for data type),
fast ordering, and fast aggregation of distinct values across these tags. Each
of these operations needs to consider the tag name and value and the value's
type.
I believe this would be a nice fit for pre-defined Range Indexes in MarkLogic
if we had a finite, predetermined set of tag names and could create distinct
elements for each tag name and could predefine a Range Index for each. But
since the set of potential tag names is unlimited, and since one tag name could
be potentially associated with values that have multiple types, we can't really
predefine anything.
Based on the documentation we've seen, we might potentially be able to get the
functionality that I describe above to work using xpath queries against the
standard indexes that MarkLogic builds when importing an XML document, but our
concern is that, in the absence of Range Indexes, we would lack scalability (we
need fast performance across a large number of objects each of which would have
a large number of tags).
Is there some way to work around this with Range Indexes?
An example fragment of data:
<item>
<tagList>
<dateTag name="attrName1">20110101</dateTag>
<stringTag name="attrName2">ABC</stringTag>
<realTag name="attrName3">1.123</realTag>
<stringTag name="attrName3">DEF</stringTag>
</tagList>
</item>
Note: we would need dateTag values to have type date, stringTag values to have
type string, and realTag values to have type real for purposes of filtering,
sorting, etc.
Thanks,
Faron
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