Crate Java Client

For a more detailed documentation how to set up and use the Crate client please refer to the client documentation on `https://crate.io/docs/`_.

The client module exposes a very simple interface to query Crate using SQL.

Installation

Maven

The easiest way to use the crate client is to include it as a dependency using Maven:

<dependency>
    <groupId>io.crate</groupId>
    <artifactId>crate-client</artifactId>
    <version>...</version>
</dependency>

You can find the latest version of the client on Bintray.

From Source

See :ref:`Development <client_develop>` for further details.

Usage

A minimal example is just a few lines of code:

import io.crate.client.CrateClient;

CrateClient client = new CrateClient("server1.crate.org:4300", "server2.crate.org:4300");
SQLResponse r = client.sql("select firstName, lastName from users").actionGet();

System.out.println(Arrays.toString(r.cols()));
// outputs ["firstName", "lastName"]

for (Object[] row: r.rows()){
    System.out.println(Arrays.toString(row));
}
// outputs the users. For example:
// ["Arthur", "Dent"]
// ["Ford", "Perfect"]

The CrateClient takes multiple servers as arguments. They are used in a round-robin fashion to distribute the load. In case a server is unavailable it will be skipped.

By default, the column data types are not serialized. In order to get these, one must defined it at the SQLRequest object:

import io.crate.client.CrateClient;

CrateClient client = new CrateClient("server1.crate.org:4300", "server2.crate.org:4300");

SQLRequest request = new SQLRequest("select firstName, lastName from users");
request.includeTypesOnResponse(true);

SQLResponse r = client.sql().actionGet();

// Get the data type of the first column
DataType dataType = r.columnTypes()[0]
System.out.print(dataType.getName())
// outputs: "string"

Note

Queries are executed asynchronous. client.sql("") will return a Future<SQLResponse> and code execution is only blocked if .actionGet() is called on it.