presto-client

presto-client-node

Distributed query engine "Presto" 's client library for node.js.

var presto = require('presto-client');
var client = new presto.Client({user: 'myname', catalog: 'hive', schema: 'default'});
 
client.execute('show schemas', function(error, data, columns){
  console.log({databases: data});
});

For queries with long process time and heavy output:

var presto = require('presto-client');
var client = new presto.Client({user: 'myname'});
 
client.execute({
  query:   'SELECT count(*) as cnt FROM tblname WHERE ...',
  catalog: 'hive',
  schema:  'default',
  columns: function(error, data){ console.log({resultColumns: data}); },
  data:    function(error, data, columns, stats){ console.log(data); },
  success: function(error, stats){},
  error:   function(error){}
});

Installation

npm install -g presto-client

Or add presto-client to your own packagen.json, and do npm install.

API

new Client(opts)

Instanciate client object and set default configurations.

• opts [object]
  • host [string]
    • presto coordinator hostname or address (default: localhost)
  • port [integer]
    • presto coordinator port (default: 8080)
  • user [string]
    • username of query (default: process user name)
  • catalog [string]
    • default catalog name
  • schema [string]
    • default schema name
  • checkInterval [integer]
    • interval milliseconds of each RPC to check query status (default: 800ms)

return value: client instance object

execute(arg, callback)

If 2nd argument callback specified, this api will be selected.

This is an API to execute queries that returns result immediately, like show schemas, show tables and others. (Using "/v1/execute" HTTP RPC.)

Execute query on Presto cluster, and fetch results.

• arg [Object or string]
• arg [String]: query string executed
  • catalog and schema must be specified in new Client() for this argument type
• arg [Object]
  • query [string]
  • catalog [string]
    • catalog string (default: instance default catalog)
  • schema [string]
    • schema string (default: intance default schema)
• callback [function(error, data, columns)]
• called once when query finished
• data
  • array of arrays of each field values
  • [ [ 'field1Value', 'field2Value', 3 ], [ 'field1Value', 'field2Value', 6 ], ... ]
• columns
  • array of field names and types
  • [ { name: 'timestamp', type: 'varchar' }, { name: 'username', type: 'varchar' }, { name: 'cnt', type: 'bigint' } ]

execute(opts)

This is an API to execute queries that really read large amount of data. (Using "/v1/statement" HTTP RPC.)

Execute query on Presto cluster, and fetch results.

Attributes of opts [object] are:

• query [string]
• catalog [string]
• schema [string]
• info [boolean :optional]
  • fetch query info (execution statistics) for success callback, or not (default false)
• cancel [function() :optional]
  • client stops fetch of query results if this callback returns true
• columns [function(error, data) :optional]
  • called once when columns and its types are found in results
  • data
    • array of field info
    • [ { name: "username", type: "varchar" }, { name: "cnt", type: "bigint" } ]
• data [function(error, data, columns, stats) :optional]
  • called per fetch of query results (may be called 2 or more)
  • data
    • array of array of each column
    • [ [ "tagomoris", 1013 ], [ "dain", 2056 ], ... ]
  • columns (optional)
    • same as data of columns callback
  • stats (optional)
    • runtime statistics object of query
• success [function(error, stats, info) :optional]
  • called once when all results are fetched (default: value of callback)
• error [function(error) :optional]
  • callback for errors of query execution (default: value of callback)
• callback [function(error, stats) :optional]
  • callback for query completion (both of success and fail)
  • one of callback or success must be specified

Callbacks order (success query) is: columns -> data (-> data xN) -> success (or callback)

nodes(opts, callback)

Get node list of presto cluster and return it.

• opts [object :optional]
  • specify null, undefined or {} (currently)
• callback [function(error,data)]
  • error
  • data
    • array of node objects

Versions

• 0.0.4:
  • send cancel request of canceled query actually
• 0.0.3:
  • simple and immediate query execution support
• 0.0.2: maintenance release
  • add User-Agent header with version
• 0.0.1: initial release

Todo

• node: "failed" node list support
• patches welcome!

Author & License

• tagomoris
• License:
  • MIT (see LICENSE)