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Originally published in Queue vol. 9, no. 3
see this item in the ACM Digital Library



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Lukas Eder | Sat, 14 Dec 2013 22:51:40 UTC

This seems more like a plea for LINQ than anything else ;-) One of LINQ's main visions is to unify querying regardless of the data source - and it does so quite well. At the time the author of this article conceived LINQ, he intended to unify querying RDBMS, XML, and objects. "NoSQL" (whatever that is) is a type of data store that was not part of LINQ's original master plan. Thus, LINQ has to be retrofitted / enhanced to accommodate new requirements. It would be all too nice if things were as easy as a simple duality, specifically given the fact that the author of this article has now also created a company called Applied Duality Inc.

But history will teach us where these things go. I currently don't see a second E.F. Codd to solve the complexity introduced with the new abundance of NoSQL data stores - yet.

Will Sisson | Sun, 30 Dec 2012 11:59:47 UTC

I am not convinced that the authors understand what the closed world assumption is.

rdm | Mon, 05 Nov 2012 16:49:05 UTC

p.s. I was thinking specifically of kx.com's implementation of sql when I wrote that comment.

rdm | Thu, 04 Oct 2012 16:50:49 UTC

I think I need to disagree with the statement "all existing SQL-based relational database products are largely indistinguishable".

Specifically, I think that an sql database implementation optimized for time-series analysis, which provides (significant) real-time performance guarantees (such as is used on wall street) is fundamentally different from the products provided by Oracle, IBM, Microsoft, ... It's true that they have things in common (they're all implementing some kind of ACID model, and there's at least a subset of SQL in common) but the customer requirements are different and the implementation architectures are different.

Kingsley Idehen | Mon, 05 Dec 2011 20:54:18 UTC

Meant to say: As clearly indicated by Kyle Geiger, 3-tuple based relations are the way forward. By leveraging HTTP URIs in the aforementioned Object, Key, Value pattern, the WWW itself becomes a distributed graph model DBMS equipped with SPARQL and SPASQL (SPARQL inside SQL) as its declarative query languages.

Kingsley Idehen | Mon, 05 Dec 2011 20:53:20 UTC

As clearly indicated by Kyle Geiger, 3-tuple based relations are the way forward. By leveraging HTTP URIs in the aforementioned Object, Key, Value pattern, the WWW itself becomes a distributed graph model DBMS equipped with SPARQL and SPASQL (SPARQL inside SQL).

Dan McCreary | Mon, 05 Dec 2011 16:40:31 UTC

I don't see why XQuery could not be a common language instead of LINQ. XQuery can also be used to query graphs. I agree with the others that LINQ would never be adopted by the NoSQL community. But there are already XQuery front ends for MarkLogic, eXist and not MongoDB. We do need a "platform" for NoSQL to be successful. But NoSQL vendors need to understand that mixed content is a big part of what we need and JSON does not support mixed content.

Karl Geiger | Sat, 16 Apr 2011 13:23:31 UTC

Marcelo Cantos and Elf Sternberg are right. It seems that after developing a pointer-based relational schema (!), the authors derive 4th Normal Form (Fig. 8). Key-value pairs, say {(isbn, title), (isbn,author), (isbn,year), (isbn,pages), (isbn,keywords), (isbn,ratings)}, represent the information more compactly, afford more flexible retrieval, and can be deployed in a fast, distributed system using existing RDBMS technologies. Implement compound keys that depend on the data, eg, "CREATE TABLE titles (isbn VARCHAR(20), title VARCHAR(100), PRIMARY KEY(isbn, title))", to preserve atomicity. 4NF supports the noSQL key-value model in SQL, so SQL is adequate fornoSQL queries.

Daniel O'Connor hints at the next step: replace sets of key-value relations with a single (object, key, value) relation: [('title', 12345, 'The Right Stuff'), ('author', 12345, 'Tom Wolfe'), ('pages', 12345, '390'), ('keywords', 12345, 'book'), ('keywords', 12345, 'hardcover')]. Distributed RDBMSes can also readily implement a triple store with good performance and known tuning tricks like partitioning and localization.

David Piepgrass | Sat, 09 Apr 2011 19:24:41 UTC

LINQ is a very nice query language, and (in case you missed the point of the article) it could certainly serve as a common query language between SQL and NoSQL/CoSQL. However, in practice it won't serve this purpose as long as it remains Microsoft-only. LINQ cannot take off as a standard query language for CoSQL until we can write LINQ for Java, LINQ for Perl and so on, and with solid Linux support.

It should also be noted that while LINQ can represent both SQL and CoSQL/NoSQL queries, a query designed for SQL tends to look very different from a query designed for an equivalent dataset stored in a CoSQL database. Still, a common language does at least ease the burden of learning many different technologies.

alexis richardson | Fri, 08 Apr 2011 15:47:07 UTC

I don't understand how the dual of a non-compositional algebra can be compositional. That is, if "dual" has the categorical meaning indicated above.

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