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93
README.md
Normal file
93
README.md
Normal file
@@ -0,0 +1,93 @@
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## pg-copy-streams
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COPY FROM / COPY TO for node-postgres. Stream from one database to another, and stuff.
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## how? what? huh?
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Did you know the _all powerful_ PostgreSQL supports streaming binary data directly into and out of a table?
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This means you can take your favorite CSV or TSV or whatever format file and pipe it directly into an existing PostgreSQL table.
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You can also take a table and pipe it directly to a file, another database, stdout, even to `/dev/null` if you're crazy!
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What this module gives you is a [Readable](http://nodejs.org/api/stream.html#stream_class_stream_readable) or [Writable](http://nodejs.org/api/stream.html#stream_class_stream_writable) stream directly into/out of a table in your database.
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This mode of interfacing with your table is _very fast_ and _very brittle_. You are responsible for properly encoding and ordering all your columns. If anything is out of place PostgreSQL will send you back an error. The stream works within a transaction so you wont leave things in a 1/2 borked state, but it's still good to be aware of.
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If you're not familiar with the feature (I wasn't either) you can read this for some good helps: http://www.postgresql.org/docs/9.3/static/sql-copy.html
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## examples
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### pipe from a table to stdout
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```js
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var pg = require('pg');
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var copyTo = require('pg-copy-streams').to;
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pg.connect(function(err, client, done) {
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var stream = client.query(copyTo('COPY my_table TO STDOUT'));
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stream.pipe(process.stdout);
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stream.on('end', done);
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stream.on('error', done);
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});
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```
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### pipe from a file to table
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```js
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var fs = require('fs');
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var pg = require('pg');
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var copyFrom = require('pg-copy-streams').from;
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pg.connect(function(err, client, done) {
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var stream = client.query(copyFrom('COPY my_table FROM STDIN'));
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var fileStream = fs.createReadStream('some_file.tdv')
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fileStream.pipe(stream);
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fileStream.on('end', done);
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fileStream.on('error', done);
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});
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```
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## install
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```sh
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$ npm install pg-copy-streams
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```
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## notice
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Before you set out on this magical piping journey, you _really_ should read this: http://www.postgresql.org/docs/9.3/static/sql-copy.html, and you might want to take a look at the [tests](https://github.com/brianc/node-pg-copy-streams/tree/master/test) to get an idea of how things work.
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## contributing
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Instead of adding a bunch more code to the already bloated [node-postgres](https://github.com/brianc/node-postgres) I am trying to make the internals extensible and work on adding edge-case features as 3rd party modules.
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This is one of those.
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Please, if you have any issues with this, open an issue.
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Better yet, submit a pull request. I _love_ pull requests.
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Generally how I work is if you submit a few pull requests and you're interested I'll make you a contributor and give you full access to everything.
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Since this isn't a module with tons of installs and dependent modules I hope we can work together on this to iterate faster here and make something really useful.
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## license
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The MIT License (MIT)
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Copyright (c) 2013 Brian M. Carlson
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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19
copy-to.js
19
copy-to.js
@@ -8,18 +8,23 @@ var util = require('util')
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var CopyStreamQuery = function(text) {
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Transform.call(this)
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this.text = text
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this._listeners = null
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this._listeners = {}
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this._copyOutResponse = null
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this.rowCount = 0
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}
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util.inherits(CopyStreamQuery, Transform)
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var eventTypes = ['close', 'data', 'end', 'error']
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CopyStreamQuery.prototype.submit = function(connection) {
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connection.query(this.text)
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this.connection = connection
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this._listeners = connection.stream.listeners('data')
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connection.stream.removeAllListeners('data')
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var self = this
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eventTypes.forEach(function(type) {
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self._listeners[type] = connection.stream.listeners(type)
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connection.stream.removeAllListeners(type)
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})
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connection.stream.pipe(this)
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}
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@@ -32,10 +37,12 @@ var code = {
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CopyStreamQuery.prototype._detach = function() {
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this.connection.stream.unpipe()
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this.connection.stream.removeAllListeners('data')
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var self = this
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this._listeners.forEach(function(listener) {
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self.connection.stream.on('data', listener)
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eventTypes.forEach(function(type) {
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self.connection.stream.removeAllListeners(type)
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self._listeners[type].forEach(function(listener) {
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self.connection.stream.on(type, listener)
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})
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})
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}
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2
index.js
2
index.js
@@ -55,7 +55,7 @@ CopyStreamQuery.prototype.handleError = function(e) {
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this.emit('error', e)
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}
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CopyStreamQuery.prototype.streamData = function(connection) {
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CopyStreamQuery.prototype.handleCopyInResponse = function(connection) {
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this.pipe(connection.stream)
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}
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@@ -1,6 +1,6 @@
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{
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"name": "pg-copy-streams",
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"version": "0.2.0",
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"version": "0.2.3",
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"description": "Low-Level COPY TO and COPY FROM streams for PostgreSQL in JavaScript using",
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"main": "index.js",
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"scripts": {
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@@ -27,6 +27,7 @@
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"concat-stream": "~1.1.0",
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"gonna": "0.0.0",
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"lodash": "~2.2.1",
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"heroku-env": "~0.1.1"
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"heroku-env": "~0.1.1",
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"async": "~0.2.10"
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}
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}
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65
test/binary.js
Normal file
65
test/binary.js
Normal file
@@ -0,0 +1,65 @@
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var assert = require('assert')
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var gonna = require('gonna')
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var async = require('async')
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var concat = require('concat-stream')
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var _ = require('lodash')
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var pg = require('pg.js')
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var from = require('../').from
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var to = require('../').to
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var testBinaryCopy = function() {
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var client = function() {
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var client = new pg.Client()
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client.connect()
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return client
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}
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var fromClient = client()
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var toClient = client()
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queries = [
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'CREATE TABLE data (num BIGINT, word TEXT)',
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'INSERT INTO data (num, word) VALUES (1, \'hello\'), (2, \'other thing\'), (3, \'goodbye\')',
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'CREATE TABLE data_copy (LIKE data INCLUDING ALL)'
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]
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async.eachSeries(queries, _.bind(fromClient.query, fromClient), function(err) {
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assert.ifError(err)
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var fromStream = fromClient.query(to('COPY (SELECT * FROM data) TO STDOUT BINARY'))
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var toStream = toClient.query(from('COPY data_copy FROM STDIN BINARY'))
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runStream = function(callback) {
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fromStream.on('error', callback)
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toStream.on('error', callback)
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toStream.on('finish', callback)
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fromStream.pipe(toStream)
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}
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runStream(function(err) {
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assert.ifError(err)
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toClient.query('SELECT * FROM data_copy ORDER BY num', function(err, res){
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assert.equal(res.rowCount, 3, 'expected 3 rows but got ' + res.rowCount)
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assert.equal(res.rows[0].num, 1)
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assert.equal(res.rows[0].word, 'hello')
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assert.equal(res.rows[1].num, 2)
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assert.equal(res.rows[1].word, 'other thing')
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assert.equal(res.rows[2].num, 3)
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assert.equal(res.rows[2].word, 'goodbye')
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queries = [
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'DROP TABLE data',
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'DROP TABLE data_copy'
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]
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async.each(queries, _.bind(fromClient.query, fromClient), function(err) {
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assert.ifError(err)
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fromClient.end()
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toClient.end()
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})
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})
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})
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})
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}
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testBinaryCopy()
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@@ -1,20 +1,21 @@
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var assert = require('assert')
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var gonna = require('gonna')
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var concat = require('concat-stream')
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var _ = require('lodash')
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var async = require('async')
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var concat = require('concat-stream')
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var pg = require('pg.js')
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var copy = require('../').to
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var client = function() {
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var client = new pg.Client()
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client.connect()
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return client
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}
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var testRange = function(top) {
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var client = function() {
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var client = new pg.Client()
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client.connect()
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return client
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}
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var fromClient = client()
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var copy = require('../').to
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var txt = 'COPY (SELECT * from generate_series(0, ' + (top - 1) + ')) TO STDOUT'
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var stream = fromClient.query(copy(txt))
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@@ -32,3 +33,28 @@ var testRange = function(top) {
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}
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testRange(10000)
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var testLeak = function(rounds) {
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var fromClient = client()
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var txt = 'COPY (SELECT 10) TO STDOUT'
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var runStream = function(num, callback) {
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var stream = fromClient.query(copy(txt))
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stream.on('data', function(data) {
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// Just throw away the data.
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})
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stream.on('end', callback)
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stream.on('error', callback)
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}
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async.timesSeries(rounds, runStream, function(err) {
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assert.equal(err, null)
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assert.equal(fromClient.connection.stream.listeners('close').length, 0)
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assert.equal(fromClient.connection.stream.listeners('data').length, 1)
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assert.equal(fromClient.connection.stream.listeners('end').length, 2)
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assert.equal(fromClient.connection.stream.listeners('error').length, 1)
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fromClient.end()
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})
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}
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testLeak(5)
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@@ -1,2 +1,3 @@
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require('./copy-from')
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require('./copy-to')
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require('./binary')
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Reference in New Issue
Block a user