vitessdriver

README

Vitess

This is the Go SQL driver for Vitess.

Vitess is an SQL middleware which turns MySQL/MariaDB into a fast, scalable and highly-available distributed database. For more information, visit www.vitess.io.

Documentation

For more information on this driver, please see its godoc page:

https://godoc.org/vitess.io/vitess/go/vt/vitessdriver

Installation

go get vitess.io/vitess/go/vt/vitessdriver

See the documentation link above for examples.

Documentation

Overview

Package vitessdriver contains the Vitess Go SQL driver.

Vitess

Vitess is an SQL middleware which turns MySQL/MariaDB into a fast, scalable and highly-available distributed database. For more information, visit http://www.vitess.io.

Example

Using this SQL driver is as simple as:

import (
  "vitess.io/vitess/go/vt/vitessdriver"
)

func main() {
  // Connect to vtgate.
  db, err := vitessdriver.Open("localhost:15991", "@primary")

  // Use "db" via the Golang sql interface.
}

For a full example, please see: https://github.com/vitessio/vitess/blob/main/test/client.go

The full example is based on our tutorial for running Vitess locally: https://vitess.io/docs/get-started/local/

Vtgate

This driver connects to a vtgate process. In Vitess, vtgate is a proxy server that routes queries to the appropriate shards.

By decoupling the routing logic from the application, vtgate enables Vitess features like consistent, application-transparent resharding: When you scale up the number of shards, vtgate becomes aware of the new shards. You do not have to update your application at all.

VTGate is capable of breaking up your query into parts, routing them to the appropriate shards and combining the results, thereby giving the semblance of a unified database.

The driver uses the V3 API which doesn't require you to specify routing information. You just send the query as if Vitess was a regular database. VTGate analyzes the query and uses additional metadata called VSchema to perform the necessary routing. See the vtgate v3 Features doc for an overview: https://github.com/vitessio/vitess/blob/main/doc/VTGateV3Features.md

As of 12/2015, the VSchema creation is not documented yet as we are in the process of simplifying the VSchema definition and the overall process for creating one. If you want to create your own VSchema, we recommend to have a look at the VSchema from the vtgate v3 demo: https://github.com/vitessio/vitess/blob/main/examples/demo/schema

(The demo itself is interactive and can be run by executing "./run.py" in the "examples/demo/" directory.)

The vtgate v3 design doc, which we will also update and simplify in the future, contains more details on the VSchema: https://github.com/vitessio/vitess/blob/main/doc/V3VindexDesign.md

Isolation levels

The Vitess isolation model is different from the one exposed by a traditional database. Isolation levels are controlled by connection parameters instead of Go's IsolationLevel. You can perform primary, replica or rdonly reads. Primary reads give you read-after-write consistency. Replica and rdonly reads give you eventual consistency. Replica reads are for satisfying OLTP workloads while rdonly is for OLAP.

All transactions must be sent to the primary where writes are allowed. Replica and rdonly reads can only be performed outside of a transaction. So, there is no concept of a read-only transaction in Vitess.

Consequently, no IsolationLevel must be specified while calling BeginContext. Doing so will result in an error.

Named arguments

Vitess supports positional or named arguments. However, intermixing is not allowed within a statement. If using named arguments, the ':' and '@' prefixes are optional. If they're specified, the driver will strip them off before sending the request over to VTGate.

Index

• Variables
• func DateToNative(v sqltypes.Value, loc *time.Location) (time.Time, error)
• func DatetimeToNative(v sqltypes.Value, loc *time.Location) (time.Time, error)
• func NewDatetime(t time.Time, defaultLoc *time.Location) sqltypes.Value
• func Open(address, target string) (*sql.DB, error)
• func OpenForStreaming(address, target string) (*sql.DB, error)
• func OpenWithConfiguration(c Configuration) (*sql.DB, error)
• type Configuration

Variables

var ErrInvalidTime = errors.New("invalid MySQL time string")

ErrInvalidTime is returned when we fail to parse a datetime string from MySQL. This should never happen unless things are seriously messed up.

Functions

func DateToNative

func DateToNative(v sqltypes.Value, loc *time.Location) (time.Time, error)

DateToNative converts a Date Value into a time.Time. Note that there's no specific type in the Go stdlib to represent dates without time components, so the returned Time will have their hours/mins/seconds zeroed out.

func DatetimeToNative

func DatetimeToNative(v sqltypes.Value, loc *time.Location) (time.Time, error)

DatetimeToNative converts a Datetime Value into a time.Time

func NewDatetime

func NewDatetime(t time.Time, defaultLoc *time.Location) sqltypes.Value

NewDatetime builds a Datetime Value

func Open

func Open(address, target string) (*sql.DB, error)

Open is a Vitess helper function for sql.Open().

It opens a database connection to vtgate running at "address".

func OpenForStreaming

func OpenForStreaming(address, target string) (*sql.DB, error)

OpenForStreaming is the same as Open() but uses streaming RPCs to retrieve the results.

The streaming mode is recommended for large results.

func OpenWithConfiguration

func OpenWithConfiguration(c Configuration) (*sql.DB, error)

OpenWithConfiguration is the generic Vitess helper function for sql.Open().

It allows to pass in a Configuration struct to control all possible settings of the Vitess Go SQL driver.

Types

type Configuration

type Configuration struct {
	// Protocol is the name of the vtgate RPC client implementation.
	// Note: In open-source "grpc" is the recommended implementation.
	//
	// Default: "grpc"
	Protocol string

	// Address must point to a vtgate instance.
	//
	// Format: hostname:port
	Address string

	// Target specifies the default target.
	Target string

	// Streaming is true when streaming RPCs are used.
	// Recommended for large results.
	// Default: false
	Streaming bool

	// DefaultLocation is the timezone string that will be used
	// when converting DATETIME and DATE into time.Time.
	// This setting has no effect if ConvertDatetime is not set.
	// Default: UTC
	DefaultLocation string

	// GRPCDialOptions registers a new vtgateconn dialer with these dial options using the
	// protocol as the key. This may overwrite the default grpcvtgateconn dial option
	// if a custom one hasn't been specified in the config.
	//
	// Default: none
	GRPCDialOptions []grpc.DialOption `json:"-"`

	// Driver is the name registered with the database/sql package. This override
	// is here in case you have wrapped the driver for stats or other interceptors.
	//
	// Default: "vitess"
	DriverName string `json:"-"`
}

Configuration holds all Vitess driver settings.

Fields with documented default values do not have to be set explicitly.