Presto JS Client

This is a Presto JavaScript client that connects to Presto via Presto's REST API to run queries.

Installation

npm install @prestodb/presto-js-client

Usage

Import the PrestoClient class from @prestodb/presto-js-client.

Create a new instance by passing the connection parameters.

Example

import PrestoClient from '@prestodb/presto-js-client'

...

const client = PrestoClient({
  catalog: 'tpcs',
  host: 'localhost',
  interval: 0,
  port: 8080,
  schema: 'tiny',
  timezone: 'America/Costa_Rica',
  user: 'root'
})

Parameters

The Presto client can be configured with the following parameters:

• host: The hostname or IP address of the Presto coordinator. (Default: http://localhost)
• port: The port number of the Presto coordinator. (Default: 8080)
• user: The username to use for authentication. (Default: undefined)
• catalog: The default catalog to use for queries. (Default: undefined)
• schema: The default schema to use for queries. (Default: undefined)
• source: The name of the source you want to use for reporting purposes (Default: presto-js-client)
• timezone: The timezone to use for queries. (Default: undefined)
• interval: The interval in milliseconds between checks for the status of a running query. (Default: 100)

Querying

The query method takes a single string parameter, which is the SQL query to be executed. The method returns a PrestoQuery object, which contains the results of the query, including the columns, data, and query ID. If the query fails, the query method will throw an error.

The string parameter to the query method must be a valid SQL query. The query can be any type of SQL query, including SELECT, INSERT, UPDATE, and DELETE statements.

Return data structure (or error state)

The query method returns a PrestoQuery object, which contains the results of the query, including the columns, data, and query ID.

If the query succeeds, the PrestoQuery object will have the following properties:

• columns: An array of objects that describe the columns in the results.
• data: An array of arrays that contain the actual data for the results.
• queryId: The ID of the query.

If the query fails, the PrestoQuery object will have the following properties:

• error: An object that contains information about the error.
• queryId: The ID of the query.

You can use the error property to get more information about the error that occurred. You can also use the queryId property to cancel the query or to get more information about the status of the query.

Example usage

The following example shows how to use the query() method to execute a SELECT statement:

const client = new PrestoClient({
  catalog: 'tpcds',
  host: 'http://localhost',
  port: 8080,
  schema: 'sf10',
  user: 'root',
})

const query = `SELECT * FROM my_table`

const prestoQuery = await client.query(query)

if (prestoQuery.error) {
  // Handle the error.
} else {
  // Use the results of the query.
}

Additional notes

Additional notes

• The query method is asynchronous and will return a promise that resolves to a PrestoQuery object.
• The query method will automatically retry the query if it fails due to a transient error.
• The query method will cancel the query if the client is destroyed.