Interface SqlService

Enabling SQL Service

To use this service, the Jet engine must be enabled on the members and the hazelcast-sql module must be in the classpath of the members. If you are using the CLI, Docker image, or distributions to start Hazelcast members, then you don't need to do anything, as the above preconditions are already satisfied for such members.

However, if you are using Hazelcast members in the embedded mode, or receiving errors saying that The Jet engine is disabled or Cannot execute SQL query because "hazelcast-sql" module is not in the classpath. while executing queries, enable the Jet engine following one of the instructions pointed out in the error message, or add the hazelcast-sql module to your member's classpath.

Overview

Hazelcast is currently able to execute distributed SQL queries using the following connectors:

• IMap
• Kafka
• Files

SQL statements are not atomic. INSERT/SINK can fail and commit part of the data.

Usage

Before you can access any object using SQL, a mapping has to be created. See the documentation for the CREATE MAPPING command.

When a query is executed, an SqlResult is returned. The returned result is an async iterable of SqlRowType. It can also be iterated using SqlResult.next method. The result should be closed at the end to release server resources. Fetching the last page closes the result. The code snippet below demonstrates a typical usage pattern:

const client = await Client.newHazelcastClient();
const result = await client.getSql().execute('SELECT * FROM persons');
for await (const row of result) {
   console.log(row.personId);
   console.log(row.name);
}
await result.close();
await client.shutdown();