GoRethink - RethinkDB Driver for Go

Go driver for RethinkDB

Current version: v0.7.2 (RethinkDB v2.0)

Please note that this version of the driver only supports versions of RethinkDB using the v0.4 protocol (any versions of the driver older than RethinkDB 2.0 will not work).

Installation

go get -u github.com/dancannon/gorethink

Connection

Basic Connection

Setting up a basic connection with RethinkDB is simple:

import (
    r "github.com/dancannon/gorethink"
)

var session *r.Session

session, err := r.Connect(r.ConnectOpts{
    Address: "localhost:28015",
})
if err != nil {
    log.Fatalln(err.Error())
}

See the documentation for a list of supported arguments to Connect().

Connection Pool

The driver uses a connection pool at all times, by default it creates and frees connections automatically. It's safe for concurrent use by multiple goroutines.

To configure the connection pool MaxIdle, MaxOpen and IdleTimeout can be specified during connection. If you wish to change the value of MaxIdle or MaxOpen during runtime then the functions SetMaxIdleConns and SetMaxOpenConns can be used.

var session *r.Session

session, err := r.Connect(r.ConnectOpts{
    Address: "localhost:28015",
    Database: "test",
    MaxIdle: 10,
    MaxOpen: 10,
})
if err != nil {
    log.Fatalln(err.Error())
}

session.SetMaxOpenConns(5)

Connect to a cluster

To connect to a RethinkDB cluster which has multiple nodes you can use the following syntax. When connecting to a cluster with multiple nodes queries will be distributed between these nodes.

var session *r.Session

session, err := r.Connect(r.ConnectOpts{
    Addresses: []string{"localhost:28015", "localhost:28016"},
    Database: "test",
    AuthKey:  "14daak1cad13dj",
    DiscoverHosts: true,
})
if err != nil {
    log.Fatalln(err.Error())
}

When DiscoverHosts is true any nodes are added to the cluster after the initial connection then the new node will be added to the pool of available nodes used by GoRethink.

Query Functions

This library is based on the official drivers so the code on the API page should require very few changes to work.

To view full documentation for the query functions check the GoDoc

Slice Expr Example

r.Expr([]interface{}{1, 2, 3, 4, 5}).Run(session)

Map Expr Example

r.Expr(map[string]interface{}{"a": 1, "b": 2, "c": 3}).Run(session)

Get Example

r.Db("database").Table("table").Get("GUID").Run(session)

Map Example (Func)

r.Expr([]interface{}{1, 2, 3, 4, 5}).Map(func (row Term) interface{} {
    return row.Add(1)
}).Run(session)

Map Example (Implicit)

r.Expr([]interface{}{1, 2, 3, 4, 5}).Map(r.Row.Add(1)).Run(session)

Between (Optional Args) Example

r.Db("database").Table("table").Between(1, 10, r.BetweenOpts{
    Index: "num",
    RightBound: "closed",
}).Run(session)

Optional Arguments

As shown above in the Between example optional arguments are passed to the function as a struct. Each function that has optional arguments as a related struct. This structs are named in the format FunctionNameOpts, for example BetweenOpts is the related struct for Between.

Results

Different result types are returned depending on what function is used to execute the query.

• Run returns a cursor which can be used to view all rows returned.
• RunWrite returns a WriteResponse and should be used for queries such as Insert, Update, etc...
• Exec sends a query to the server and closes the connection immediately after reading the response from the database. If you do not wish to wait for the response then you can set the NoReply flag.

Example:

res, err := r.Db("database").Table("tablename").Get(key).Run(session)
if err != nil {
    // error
}
defer res.Close() // Always ensure you close the cursor to ensure connections are not leaked

Cursors have a number of methods available for accessing the query results

• Next retrieves the next document from the result set, blocking if necessary.
• All retrieves all documents from the result set into the provided slice.
• One retrieves the first document from the result set.

Examples:

var row interface{}
for res.Next(&row) {
    // Do something with row
}
if res.Err() != nil {
    // error
}

var rows []interface{}
err := res.All(&rows)
if err != nil {
    // error
}

var row interface{}
err := res.One(&row)
if err == r.ErrEmptyResult {
    // row not found
}
if err != nil {
    // error
}

Encoding/Decoding Structs

When passing structs to Expr(And functions that use Expr such as Insert, Update) the structs are encoded into a map before being sent to the server. Each exported field is added to the map unless

• the field's tag is "-", or
• the field is empty and its tag specifies the "omitempty" option.

Each fields default name in the map is the field name but can be specified in the struct field's tag value. The "gorethink" key in the struct field's tag value is the key name, followed by an optional comma and options. Examples:

// Field is ignored by this package.
Field int `gorethink:"-"`
// Field appears as key "myName".
Field int `gorethink:"myName"`
// Field appears as key "myName" and
// the field is omitted from the object if its value is empty,
// as defined above.
Field int `gorethink:"myName,omitempty"`
// Field appears as key "Field" (the default), but
// the field is skipped if empty.
// Note the leading comma.
Field int `gorethink:",omitempty"`

Alternatively you can implement the FieldMapper interface by providing the FieldMap function which returns a map of strings in the form of "FieldName": "NewName". For example:

type A struct {
    Field int
}

func (a A) FieldMap() map[string]string {
    return map[string]string{
        "Field": "myName",
    }
}

Benchmarks

Everyone wants their project's benchmarks to be speedy. And while we know that rethinkDb and the gorethink driver are quite fast, our primary goal is for our benchmarks to be correct. They are designed to give you, the user, an accurate picture of writes per second (w/s). If you come up with a accurate test that meets this aim, submit a pull request please.

Thanks to @jaredfolkins for the contribution.

BenchmarkBatch200RandomWrites                20                              557227775                     ns/op
BenchmarkBatch200RandomWritesParallel10      30                              354465417                     ns/op
BenchmarkBatch200SoftRandomWritesParallel10  100                             761639276                     ns/op
BenchmarkRandomWrites                        100                             10456580                      ns/op
BenchmarkRandomWritesParallel10              1000                            1614175                       ns/op
BenchmarkRandomSoftWrites                    3000                            589660                        ns/op
BenchmarkRandomSoftWritesParallel10          10000                           247588                        ns/op
BenchmarkSequentialWrites                    50                              24408285                      ns/op
BenchmarkSequentialWritesParallel10          1000                            1755373                       ns/op
BenchmarkSequentialSoftWrites                3000                            631211                        ns/op
BenchmarkSequentialSoftWritesParallel10      10000                           263481                        ns/op

Examples

View other examples on the wiki.

License

Copyright 2013 Daniel Cannon

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.