N1QL Queries from the SDK

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    You can query for documents in Couchbase using the N1QL query language, a language based on SQL, but designed for structured and flexible JSON documents. Querying can solve typical programming tasks such as finding a user profile by email address, facebook login, or user ID.

    Our query service uses N1QL, which will be fairly familiar to anyone who’s used any dialect of SQL. Further resources for learning about N1QL are listed at the bottom of the page. Before you get started you may wish to checkout the N1QL intro page, or just dive in with a query against our travel sample data set. In this case, the one thing that you need to know is that in order to make a Bucket queryable, it must have at least one index defined. You can define a _primary index on a bucket. When a primary index is defined you can issue non-covered queries on the bucket as well.

    Use cbq, our interactive Query shell. Open it, and enter the following:

    CREATE PRIMARY INDEX ON `travel-sample`

    or replace travel-sample with a different Bucket name to build an index on a different dataset.

    The default installation places cbq in /opt/couchbase/bin/ on Linux, /Applications/Couchbase Server.app/Contents/Resources/couchbase-core/bin/cbq on OS X, and C:\Program Files\Couchbase\Server\bin\cbq.exe on Microsoft Windows.

    ReadOnly

    If the query is marked as readonly, both the server and the SDK can improve processing of the operation. On the client side, the SDK can be more liberal with retries because it can be sure that there are no state-mutating side-effects happening. The query engine will ensure that actually no data is mutated when parsing and planning the query.

    Additional Resources

    N1QL is not the only query option in Couchbase. Be sure to check that your use case fits your selection of query service.

    The Server doc N1QL intro introduces up a complete guide to the N1QL language, including all of the latest additions.

    The N1QL interactive tutorial is a good introduction to the basics of N1QL use.