0.4.0 • Published 1 year ago

presto-client_custom v0.4.0

Weekly downloads
-
License
MIT
Repository
github
Last release
1 year ago

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',
  state:   function(error, query_id, stats){ console.log({message:"status changed", id:query_id, stats:stats}); },
  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)
    • ssl object
      • Setting a Hash object enables SSL and verify server certificate with options (default: null):
        • ca: An authority certificate or array of authority certificates to check the remote host against
        • cert: Public x509 certificate to use (default : null)
        • ciphers : Default cipher suite to use. (default: https://nodejs.org/api/tls.html#tls_modifying_the_default_tls_cipher_suite)
        • key: Private key to use for SSL (default: null)
        • passphrase: A string of passphrase for the private key or pfx (default: null)
        • pfx: Certificate, Private key and CA certificates to use for SSL. (default: null).
        • rejectUnauthorized: If not false the server will reject any connection which is not authorized with the list of supplied CAs. This option only has an effect if requestCert is true (default: true)
        • secureProtocol: Optional SSL method to use. The possible values are listed as SSL_METHODS, use the function names as strings. For example, "SSLv3_method" to force SSL version 3 (default: SSLv23_method)
        • servername: Server name for the SNI (Server Name Indication) TLS extension
    • port integer
      • Presto coordinator port (default: 8080)
    • user string
      • Username of query (default: process user name)
    • basic_auth object
      • Pass in a user and password to enable Authorization Basic headers on all requests.
      • basic_auth: {user: "user", password: "password"} (default:null)
    • catalog string
      • Default catalog name
    • schema string
      • Default schema name
    • checkInterval integer
      • Interval milliseconds of each RPC to check query status (default: 800ms)
    • enableVerboseStateCallback boolean
      • Enable more verbose callback for Presto query states (default: false)
      • When set to true, this flag modifies the condition of the state change callback to return data every checkInterval(default: 800ms). Modify checkInterval if you wish to change the frequency.
      • Otherwise (false), the state change callback will only be called upon a change in state.
      • The purpose of this variable is to enable verbose update capability in state callbacks. This is such that "percentage complete" and "processed rows" may be extracted despite the state still remaining in a particular state eg. "RUNNING".
    • jsonParser object
      • Custom json parser if required (default: JSON)

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
  • 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:

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

query(query_id, callback)

Get query current status. (Same with 'Raw' of Presto Web in browser.)

kill(query_id, callback)

Stop query immediately.

nodes(opts, callback)

Get node list of presto cluster and return it.

BIGINT value handling

Javascript standard JSON module cannot handle BIGINT values correctly by precision problems.

JSON.parse('{"bigint":1139779449103133602}').bigint //=> 1139779449103133600

If your query puts numeric values in its results and precision is important for that query, you can swap JSON parser with any modules which has parse method.

var JSONbig = require('json-bigint');
JSONbig.parse('{"bigint":1139779449103133602}').bigint.toString() //=> "1139779449103133602"
// set client option
var client = new presto.Client({
  // ...
  jsonParser: JSONbig,
  // ...
});

Versions

  • 0.4.0:
    • add a parameter to call status callback in verbose
  • 0.3.0:
    • add Basic Authentication support
  • 0.2.0:
    • add HTTPS support
  • 0.1.3:
    • add X-Presto-Time-Zone if "timezone" specified
  • 0.1.2:
    • add X-Presto-Session if "session" specified
  • 0.1.1:
    • fix bug not to handle HTTP level errors correctly
  • 0.1.0:
    • add option to pass customized json parser to handle BIGINT values
    • add check for required callbacks of query execution
  • 0.0.6:
    • add API to get/delete queries
    • add callback state on query execution
  • 0.0.5:
    • fix to do error check on query execution
  • 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)
presto
@everything-registry/sub-chunk-2470
0.4.0

1 year ago