A N1QL for every Query¶
The real world isn’t all structured and ordered.
In the traditional (relational) data model, you need to fit the data you have into the model you’ve decided on. In the rich data model, your data is varied, and your schema may vary . In the traditional (relational) data model, data must all fit into the same shape, and changing that shape can be costly. In the rich (document-oriented) data model, data can fit into a multitude of shapes, and those shapes can change easily.
SQL works well for the traditional data model, but not so well for the rich data model, where schemas are shifting.
What is N1QL?¶
N1QL embraces the JSON document model, with SQL-like syntax to ease transition. It works with structured, semi-structured, and unstructured data. JSON is fully supported, and more formats may be supported in future.
N1QL supports aggregations, filtering and transformations. You can, for example, transform one array into another array. In SQL when you run an operation, you get a result set consisting of a series of rows. In N1QL, you operate on JSON documents, and the result of your operation is another JSON document.
The “N1” comes from non-first normal form - we have multivalued attributes and nested objects.
Whilst views are fairly heavy weight, N1QL allows you to have high performance declarative indexes which are lighter weight.
A query in N1QL has three parts to it:
- SELECT - what parts of each document do you want?
- FROM - what data bucket or data store do you want it from?
- WHERE - what conditions must be met for a document to be returned?
The output is in the form of a JSON document.
N1QL supports string operations such as concatenation and string matching (including support for wildcards).
N1QL also supports GROUP BY, ORDER BY, as well as pagination constructs such as LIMIT and OFFSET. Other functions such as AVG, ROUND, TRUNC, SUM, MIN and MAX .
N1QL handles missing values differently from NULL values (missing means that attribute doesn’t exist in the document, NULL that it does exist, but is NULL). You can select between these two conditions using IS MISSING and IS NULL.
N1QL also allows you to join data between multiple buckets.
|||Ilam said he doesn’t like the term schemaless, since data in NoSQL databases still have schemas, it’s just that they’re flexible, and may vary between values.|
|||Ilam mentioned that a commonly asked question was whether user-defined functions are supported. This feature is planned, but not currently available.|