thrift-hive

Hive client using the Apache Thrift RPC system

npm install thrift-hive
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Thrift Hive - Hive client using the Apache Thrift RPC system

Hive client with the following main features:

  • fetch rows with optional batch size
  • implement Node Readable Stream API (including pipe)
  • hive multiple version support
  • multiple query support through the multi_execute and multi_query functions
  • advanced comments parsing

The project export the Hive API using Apache Thrift RPC system. It support multiple versions and a readable stream API.

Installation

npm install thrift-hive

Quick example

var hive = require('thrift-hive');
// Client connection
var client = hive.createClient({
  version: '0.7.1-cdh3u2',
  server: '127.0.0.1',
  port: 10000,
  timeout: 1000
});
// Execute call
client.execute('use default', function(err){
  // Query call
  client.query('show tables')
  .on('row', function(database){
    console.log(database);
  })
  .on('error', function(err){
    console.log(err.message);
    client.end();
  });
  .on('end', function(){
    client.end();
  });
});

Hive Client

We've added a function hive.createClient to simplify coding. However, you are free to use the raw Thrift API. The client take an options object as its argument andexpose an execute and a query methods.

Available options

  • version
    default to '0.7.1-cdh3u2'
  • server
    default to '127.0.0.1'
  • port
    default to 10000
  • timeout
    default to 1000 milliseconds

Available API

  • client
    A reference to the thrift client returned by thrift.createClient
  • connection
    A reference to the thrift connection returned by thrift.createConnection
  • end([callback])
    Close the Thrift connection
  • execute(query, [callback])
    Execute a query and, when done, call the provided callback with an optional error.
  • query(query, [size])
    Execute a query and return its results as an array of arrays (rows and columns). The size argument is optional and indicate the number of row to return on each fetch.
hive = require 'thrift-hive'
# Client connection
client = hive.createClient
  version: '0.7.1-cdh3u2'
  server: '127.0.0.1'
  port: 10000
  timeout: 1000
# Execute
client.execute 'USE default', (err) ->
  console.log err.message if err
  client.end()

Hive Query

The client.query function implement the EventEmitter API.

The following events are emitted:

  • row Emitted for each row returned by Hive. Contains a two arguments, the row as an array and the row index.
  • row-first Emitted after the first row returned by Hive. Contains a two arguments, the row as an array and the row index (always 0).
  • row-last Emitted after the last row returned by Hive. Contains a two arguments, the row as an array and the row index.
  • error Emitted when the connection failed or when Hive return an error.
  • end Emitted when there are no more rows to retrieve, not called if there was an error before.
  • both Convenient event combining the error and end events. Emitted when an error occured or when there are no more rows to retrieve. Return the same arguments than the error or end event depending on the operation outturn.

The client.query function return a Node readable stream. It is possible to pipe the data into a writable stream but it is your responsibility to emit the data event, usually inside the row event.

The following code written in CoffeeScript is an example of piping data returned by the query into a writable stream.

fs = require 'fs'
hive = require 'thrift-hive'
# Client connection
client = hive.createClient
  version: '0.7.1-cdh3u2'
  server: '127.0.0.1'
  port: 10000
  timeout: 1000
# Execute query
client.query('show tables')
.on 'row', (database) ->
  this.emit 'data', 'Found ' + database + '\n'
.on 'error', (err) ->
  client.end()
.on 'end', () ->
  client.end()
.pipe( fs.createWriteStream "#{__dirname}/pipe.out" )

Here's the same example as the one in the "Quick example" section but using the native thrift API.

var assert     = require('assert');
var thrift     = require('thrift');
var transport  = require('thrift/lib/thrift/transport');
var ThriftHive = require('../lib/0.7.1-cdh3u2/ThriftHive');
// Client connection
var options = {transport: transport.TBufferedTransport, timeout: 1000};
var connection = thrift.createConnection('127.0.0.1', 10000, options);
var client = thrift.createClient(ThriftHive, connection);
// Execute query
client.execute('use default', function(err){
  client.execute('show tables', function(err){
    assert.ifError(err);
    client.fetchAll(function(err, databases){
      if(err){
        console.log(err.message);
      }else{
        console.log(databases);
      }
      connection.end();
    });
  });
});

Multi queries

For conveniency, we've added two functions, multi_execute and multi_query which may run multiple requests in sequential mode inside a same client connection. They are both the same except how the last query is handled:

  • multi_execute will end with an execute call, thus it's API is the same as the execute function.
  • multi_query will end with a query call, thus it's API is the same as the query function.

They accept the same arguments as their counterpart but the query may be an array or a string of queries. If it is a string, it will be split into multiple queries. Note, the parser is pretty light, removing ';' and comments but it seems to do the job.

Testing

Run the samples:

node samples/execute.js
node samples/query.js
node samples/style_native.js
node samples/style_sugar.js

Run the tests with expresso:

Hive must be started with Thrift support. By default, the tests will connect to Hive Thrift server on the host localhost and the port 10000. Edit the file "./test/config.json" if you wish to change the connection settings used accross the tests. A database test_database will be created if it does not yet exist and all the tests will run on it.

npm install -g expresso
expresso -s
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