Archive for the ‘N1QL’ Category

N1QL – It Makes Cents! [Rediscovery of Paths]

Friday, October 11th, 2013

N1QL – It Makes Cents! by Robin Johnson.

*Ba Dum Tschhh* …See what I did there? Makes cents? Get it? Haha.

So… N1QL (pronounced Nickel)… Couchbase’s new next-generation query language; what is it? Well, it’s a rather genius designed, human readable / writable, extensible language designed for ad-hoc and operational querying within Couchbase. For those already familiar with querying within Couchbase, that blurb will probably make sense to you. If not – well, probably not, so let me clear it up a little more.

But before I do that, I must inform you that this blog article isn’t the best place for you to go if you want to dive in and get started learning N1QL. It is a view into N1QL from a developer’s perspective including why I am so excited about it, and the features I am proud to point out. If you want to get started learning about N1QL, click here. Or alternatively, go and have a go of the Online Tutorial. Anyway, back to clearing up what I mean when I say N1QL…

“N1QL is similar to the standard SQL language for relational databases, but also includes additional features; which are suited for document-oriented databases.” N1QL has been designed as an intuitive Query Language for use on databases structured around Documents instead of tables. To locate and utilise information in a document-oriented database, you need the correct logic and expressions for navigating documents and document structures. N1QL provides a clear, easy-to-understand abstraction layer to query and retrieve information in your document-database.

Before we move on with N1QL, let’s talk quickly about document modeling within Couchbase. As you probably know; within Couchbase we model our documents primarily in JSON. We’re all familiar with JSON, so I won’t go into it in detail, but one thing we need to bear in mind is the fact that: our JSON documents can have complex nested data structures, nested arrays and objects which ordinarily would make querying a problem. Contrary to SQL though, N1QL has the ability to navigate nested data because it supports the concept of paths. This is very cool. We can use paths by using a dot-notation syntax to give us the logical location of an attribute within a document. For example; if we had an e-commerce site with documents containing customers’ orders, we could look inside those documents, to an Nth nested level for attributes. So if we wanted to look for the customer’s shipping street: (emphasis in original)

Paths are “very cool,” but I thought that documents could already be navigated by paths?

Remembering: XSL Transformations (XSLT) Version 2.0, XSLT 2.0 and XQuery 1.0 Serialization (Second Edition), and XQuery 1.0 and XPath 2.0 Functions and Operators (Second Edition).

Yes?

True, CouchDB uses JSON documents but the notion of paths in data structures isn’t news.

Not having paths into data structures, now, that would be news. 😉