@dalongrong/presto-client v0.6.5
presto-client-node
fork from https://github.com/tagomoris/presto-client-node and add presto-gateway support
Distributed query engine "Presto" 's client library for node.js.
var presto = require('@dalongrong/presto-client');
var client = new presto.Client({user: 'myname'});
client.execute({
query: 'SELECT count(*) as cnt FROM tblname WHERE ...',
catalog: 'memory',
schema: 'default',
source: 'nodejs-client',
routingGroup: 'scheduled',
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 @dalongrong/presto-client
Or add @dalongrong/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 notfalse
the server will reject any connection which is not authorized with the list of supplied CAs. This option only has an effect if requestCert istrue
(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
- Setting a Hash object enables SSL and verify server certificate with options (default:
- port integer
- Presto coordinator port (default: 8080)
- user string
- Username of query (default: process user name)
- source string
- Source of query (default: nodejs-client)
- routingGroup
- presto-gateway routingGroup name (default: adhoc)
- 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 everycheckInterval
(default: 800ms). ModifycheckInterval
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
)
- Custom json parser if required (default:
- host string
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
- routingGroup string :optional presto-gateway routingGroup name
- 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
- client stops fetch of query results if this callback returns
- 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
- id string like
- stats
- object which contains running query status
- called when query stats changed
- 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
- same as data of
- stats (optional)
- runtime statistics object of query
- success function(error, stats, info) :optional
- called once when all results are fetched (default: value of
callback
)
- called once when all results are fetched (default: value of
- error function(error) :optional
- callback for errors of query execution (default: value of
callback
)
- callback for errors of query execution (default: value of
- callback function(error, stats) :optional
- callback for query completion (both of success and fail)
- one of
callback
orsuccess
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)
- specify null, undefined or
- callback function(error,data)
- error
- data
- array of node objects
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,
// ...
});