One of my co-workers contributed this gem to our project. Since it combines
two sources of endless discussion on the Forum, I thought it only fitting... (01)
-Ed (02)
-----Original Message-----
From: Weber, Martin S
Sent: Friday, February 01, 2013 2:46 PM
Subject: Big Data Logic Stack? (03)
last time I mentioned that some big data stacks actually are now using logic
representation and or query languages. (04)
Two examples for this:
a) the datomic database which uses a datom as the atomic unit of storage.
>From http://www.infoq.com/articles/Datomic-Information-Model : (05)
"Every database has a fundamental unit at the bottom of its model, e.g. a
relation, row or document. For Datomic, that unit is the atomic fact, something
we call a Datom.
A Datom has the following components: (06)
* Entity (07)
* Attribute (08)
* Value (09)
* Transaction (database time) (010)
* Add/Retract (011)
This representation has obvious similarities to the Subject/Predicate/Object
data model of RDF <http://en.wikipedia.org/wiki/Resource_Description_Framework>
statements. However, without a temporal notion or proper representation of
retraction, RDF statements are insufficient for representing historical
information. Being oriented toward business information systems, Datomic adopts
the closed-world assumption, avoiding the challenges of universal naming,
open-world, shared semantics etc of the semantic web
<http://en.wikipedia.org/wiki/Semantic_Web>. A Datom is a minimal and
sufficient representation of a fact." (012)
The other part where logic comes in in 'big data' database stacks, is with
Cascalog. I'm just reading a Big Data book which completely focusses on
JCascalog (you might know it from Jena for instance) as the querying language.
Datomic also uses cascalog as its native query mechanism (which doesn't have to
be bound to the database at all, so you can do ad-hoc queries, too, using the
cascalog logic in your business logic). (013)
Cascalog in turns is an adoption of datalog, drawing from its prolog heritage. (014)
So there you go, logic facts both at the datum level (in the case of
datomic) as well as on the query level (with cascalog). State of the art:
finally begin using yesterday's techniques. (015)
Regards,
-Martin (016)
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