embedded

Dolt Database Driver

This package provides a database/sql compatible driver for embedding Dolt inside a Go application. It allows you to access local Dolt databases via the file system, akin to SQLite, without running a Dolt server process.

For details of the database/sql package see this tutorial. Below I will cover things that are specific to using dolt with this database driver.

Ways to Set up a Dolt Database

Create a directory to house one or more dolt databases. Once this is created we'll create a directory for our first database using the dolt cli

mkdir dbs
mkdir dbs/testdb
cd dbs/testdb
dolt init

Alternatively you could clone a database from dolthub or a different remote:

mkdir dbs
cd dbs
dolt clone <REMOTE URL>

Finally, you can create the dbs directory as shown above and then create the database in code using a SQL CREATE TABLE statement

Connecting to the Database

First we'll import the dolt driver so that it will be registered

_ "github.com/dolthub/driver"

Then we will open a connection to the database (recommended):

import (
    "context"
    "database/sql"
    "time"

    "github.com/cenkalti/backoff/v4"
    embedded "github.com/dolthub/driver"
)

cfg, err := embedded.ParseDSN("file:///path/to/dbs?commitname=Your%20Name&[email protected]&database=databasename")
if err != nil {
    // handle error
}

// Optional: configure retries during engine open (e.g. lock contention).
// Retries are bounded by context (e.g. PingContext).
cfg.BackOff = backoff.NewExponentialBackOff()

connector, err := embedded.NewConnector(cfg)
if err != nil {
    // handle error
}

db := sql.OpenDB(connector)
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
defer cancel()
_ = db.PingContext(ctx)

Now you can use your db as you would normally, however you have access to all of dolt's special features as well.

Dolt Data Source Names

The Dolt driver requires a DSN containing the directory where your databases live, and the name and email that are used in the commit log.

commitname - The name of the committer seen in the dolt commit log
commitemail - The email of the committer seen in the dolt commit log
database - The initial database to connect to
multistatements - If set to true, allows multiple statements in one query
clientfoundrows - If set to true, returns the number of matching rows instead of the number of changed rows in UPDATE queries

Retries on open (driver retries)

Retries during embedded engine open are configured via Config.BackOff passed to embedded.NewConnector. Retries are bounded by the context passed to Connect (typically via db.PingContext(...) or the first operation).

Example DSN

file:///path/to/dbs?commitname=Your%20Name&[email protected]&database=databasename

Multi-Statement Support

If you pass the multistatements=true parameter in the DSN, you can execute multiple statements in one query. The returned rows allow you to iterate over the returned result sets by using the NextResultSet method, just like you can with the MySQL driver.

rows, err := db.Query("SELECT * from someTable; SELECT * from anotherTable;")
// If an error is returned, it means it came from the first statement
if err != nil {
	panic(err)
}

for rows.Next() {
	// process the first result set
}

if rows.NextResultSet() {
    for rows.Next() {
        // process the second result set
    }
} else {
	// If NextResultSet returns false when there were more statements, it means there was an error,
	// which you can access through rows.Err()
	panic(rows.Err())
}