roachjs v0.2.20

RoachJS - CockroachDB Driver

• Introduction
• Installation
• Documentation
• CockroachDB

Introduction

This client is a port from the original Golang client. Internally it's is more or less the same, but this driver provides a friendlier javascript interface.

Installation

$ npm install roachjs

Documentation

• Examples
  • Initiating a client
  • Basic client usage I
  • Advanced client usage I (Prepare & Flush)
  • Advanced client usage II (Transactions)
• Interface
  • new Client(opts)
    • .get(key, callback)
    • .put(key, value, callback)
    • .conditionalPut(key, value, ifValue, callback)
    • .increment(key, increment, callback)
    • .contains(key, callback)
    • .scan(start_key, end_key, limit, callback)
    • .delete(key, callback)
    • .deleteRange(start_key, end_key, limit, callback)
    • .prepare()
      • .flush(callback)
    • .runTransaction(opts, transaction, callback)
• Extra
  • Response properties
  • Transaction function
  • Compiling .proto files
  • Custom clock module

Examples

Initiating a client

var Roach = require('roachjs')

var client = new Roach({
    uri: 'https://localhost:8080'
})

module.exports = client

Basic client usage I

client.get("sample_key", function(err, value, res) {
    if(err) throw err

    client.put("other_key", value, function(err, res) {
        if(err) {
            // Failed
        }
        else {
            // Sucess
        }
    })
})

Advanced client usage I (Prepare & Flush)

// You should prepare your queries and send them in a single batch
// For optimal performance
var c = client.prepare()

// This callback will be the first to be executed
c.get("sample_key", function(err, value, res) {
    if(err) throw err

    // Do something...
})

c.get("sample_key2", function(err, value, res) {
    if(err) throw err

    // Do something...
})

c.put("some_key", "some_value", function(err) {
    if(err) throw err

    // Do something
})

// The flush callback is the last one to be called
c.flush(function(err, res) {
    if(err) throw err

    console.log('Sucessfuly flushed %d queries.', res.responses.length)
})

Advanced client usage II (Transactions)

var opts = {
    name: "transaction example",
}

var errNoApples = new Error('Insufficient apples!')

var transaction = function(txn, commit, abort) {
    txn.get("applesInStock", function(err, value, res) {
        if(err || applesInStock.err) {
                return abort(err)
            }

            var dispatch = 5
            var inStock = parseInt(applesInStock.value)

            if(inStock < dispatch) {
                return abort(errNoApples)
        }

        // Upgrade for a prepared client
        txn = txn.prepare()

        txn.increment("applesInStock", -dispatch)
        txn.increment("applesInRoute", +dispatch)

        // Commit automatically flushes
        commit()
    })
}

client.runTransaction(opts, transaction, function(err, res) {
    if(err === errNoApples) {
        // Alert user there are no more apples...
    }
    else if(err) {
        // Transaction failed...
    }
    else {
        // Transaction commited...
    }
})

Interface

new Client(opts)

Returns a new roachjs client with options.

Parameters

Client options

Methods

client.get(key, callback)

Gets a single entry from the datastore, specified by key.

Parameters

Callback

Example

client.get("key", function(err, value, res) {})

client.put(key, value, callback)

Puts a value in the datastore in the specified key. Ideally you should send in buffers, but you can pass a string, preferably an utf-8 encoded string.

Parameters

Callback

Example

client.put("key", "value", function(err, res) {})

client.conditionalPut(key, value, ifValue, callback)

ConditionalPut sets the value for a key if the existing value matches the ifValue. Specifying an empty or null ifValue means the entry must not yet exist.

Parameters

Callback

Example

client.conditionalPut("status", "running", "stopped", function(err, actualValue, res) {})
client.conditionalPut("status", "new", null, function(err, actualValue, res) {})

client.contains(key, callback)

Contains determines if a key exists in the datastore.

Parameters

Callback

Example

client.contains("john", function(err, exists, res) {
    if(exists === true) {
        // john exists in the datastore
    }
})

client.increment(key, increment, callback)

Increment increments the value at the specified key by some increment value. Once called for a key, Put & Get will return errors; only Increment will continue to be a valid command. The value must be deleted before it can be reset using Put.

Parameters

Callback

Example

client.increment("counter", 5, function(err, newValue, res) {
    console.log('counter current value is', newValue)
})

client.scan(start_key, end_key, limit, callback)

Scan the datastore for keys in the range of the start_key and end_key, limiting the result by limit.

Parameters

Callback

Example

client.scan("a", "Z", 100, function(err, rows, res) {
    for(row as rows) {
        console.log(row)
    }
})

client.delete(key, callback)

Delete an entry from the datastore specified by key.

Parameters

Callback

Example

client.delete("key", function(err, res) {})

client.deleteRange(start_key, end_key, limit, callback)

Delete all keys found in a range, from start_key to end_key, limited by limit.

Parameters

Callback

Example

client.deleteRange("a", "Z", 100, function(err, deleted, res) {
    console.log('deleted %d entries', deleted)
})

client.prepare()

Return you a new prepared client. It has all the methods from the original client. Read Advanced client usage II to understand how to use this client. You should always use this client when sending in multiple queries, this will batch them together in a single request.

Methods

Example

var c = client.prepare()

c.get("key", function(err, value, res) {
    // Do something...
})

c.get("key2", function(err, value, res) {
    // Do something...
})

c.put("key3", "value", function(err, res) {
    // Do something...
})

c.flush()

client.flush(callback)

Flush the prepared queries buffer, and send it as a batch request.

Parameters

Callback

Example

client.flush(function(err, res) {
    if(err) {
        // Flush failed..
    }
    else {
        console.log('flushed %d queries.', res.responses.length)
    }
})

Returns

Returns an response object.

client.runTransaction(opts, transaction, callback)

RunTransaction executes a retryable transaction function in the context of a distributed transaction. The transaction is automatically aborted if retryable function returns any error aside from recoverable internal errors, and is automatically committed otherwise. retryable should have no side effects which could cause problems in the event it must be run more than once. The opts contains transaction settings.

Parameters

Transaction options

Callback

Extra

Response properties

The res argument contains the full database response, each database command can contain a different set of properties. This document will try to state some of the possible properties.

Properties

Transaction function

The transaction function is an retryable function, it may be executed more than once. This function should never forget to call commit or abort. Throwing an error inside this function also aborts the transaction.

Arguments

• abort() accepts an optional Error. This error will be passed to the .runTransaction callback.

Example

var transaction = function(txn, commit, abort) {
    txn = txn.prepare()

    for(var i = 0; i < 100; i++) {
        var key = i.toString()

        txn.put(key, "hello")
    }

    // Commit automatically flushes
    // the prepared transaction.
    commit()
}

Compiling .proto files

Cockroachdb's protocol buffer files are mantained at a repository called cockroachdb/cockroach-proto, this is maintained as a subtree in this library, in case you need to manually update or change them, follow this steps.

If you want to sync them with the latest proto files

You will need to update the folder cockroach-proto with the latest content of the cockroachdb/cockroach-proto repository, you could do this with:

$ git subtree pull -P cockroach-proto git@github.com:cockroachdb/cockroach-proto.git master --squash

• Notice: I'm not sure if this is a good pattern, just be sure to update the folder contents.

Recompile the .proto files

Run the following npm script to compile the .proto files to javascript, it will automatically place the files in the lib folder.

$ npm run build-proto

Custom clock module

You may wan't to use a custom clock module in some cases, you can pass it through the clock option, when instantiating a new Client. Your clock module should have a now method, and this method should return the current timestamp in nanoseconds, here is an example:

var clockModule = module.exports = {
    now: function TimestampNanoseconds() {
        // Should return the current timestamp in nanoseconds
        return ...;
    }
}

var client = new Client({
    clock: clockModule
})

Maintainers

• herenow