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'});
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 againstcert
: 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]
- schema [string]
- 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(opts)
This is an API to execute queries. (Using "/v1/statement" HTTP RPC.)
Execute query on Presto cluster, and fetch results.
Attributes of opts [object] are:
- query [string]
- catalog [string]
- schema [string]
- timezone [string :optional]
- 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
- state [function(error, query_id, stats) :optional]
- called when query stats changed
stats.state
: QUEUED, PLANNING, STARTING, RUNNING, FINISHED, or CANCELED, FAILED
- query_id
- id string like
20140214_083451_00012_9w6p5
- stats
- object which contains running query status
- 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)
query(query_id, callback)
Get query current status. (Same with 'Raw' of Presto Web in browser.)
- query_id [string]
- callback [function(error, data)]
kill(query_id, callback)
Stop query immediately.
- query_id [string]
- callback [function(error) :optional]
nodes(opts, callback)
Get node list of presto cluster and return it.
- opts [object :optional]
- specify null, undefined or
{}
(currently)
- callback [function(error,data)]
BIGINT value handling
Javascript standard JSON
module cannot handle BIGINT values correctly by precision problems.
JSON.parse('{"bigint":1139779449103133602}').bigint
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()
var client = new presto.Client({
jsonParser: JSONbig,
});
Versions
- 0.5.0:
- remove support for execute(arg, callback) using
/v1/execute
- 0.4.0:
- add a parameter to call status callback in verbose
- 0.3.0:
- add Basic Authentication support
- 0.2.0:
- 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