...
▽

Package pq

import "github.com/lib/pq"
Overview
Index
Examples
Subdirectories

Overview ▾

Package pq is a pure Go Postgres driver for the database/sql package.

In most cases clients will use the database/sql package instead of using this package directly. For example: 

import (
	"database/sql"

	_ "github.com/lib/pq"
)

func main() {
	connStr := "user=pqgotest dbname=pqgotest sslmode=verify-full"
	db, err := sql.Open("postgres", connStr)
	if err != nil {
		log.Fatal(err)
	}

	age := 21
	rows, err := db.Query("SELECT name FROM users WHERE age = $1", age)
	…
}

You can also connect to a database using a URL. For example: 

connStr := "postgres://pqgotest:password@localhost/pqgotest?sslmode=verify-full"
db, err := sql.Open("postgres", connStr)

Connection String Parameters

Similarly to libpq, when establishing a connection using pq you are expected to supply a connection string containing zero or more parameters. A subset of the connection parameters supported by libpq are also supported by pq. Additionally, pq also lets you specify run-time parameters (such as search_path or work_mem) directly in the connection string. This is different from libpq, which does not allow run-time parameters in the connection string, instead requiring you to supply them in the options parameter.

For compatibility with libpq, the following special connection parameters are supported:

  • dbname - The name of the database to connect to
  • user - The user to sign in as
  • password - The user's password
  • host - The host to connect to. Values that start with / are for unix domain sockets. (default is localhost)
  • port - The port to bind to. (default is 5432)
  • sslmode - Whether or not to use SSL (default is require, this is not the default for libpq)
  • fallback_application_name - An application_name to fall back to if one isn't provided.
  • connect_timeout - Maximum wait for connection, in seconds. Zero or not specified means wait indefinitely.
  • sslcert - Cert file location. The file must contain PEM encoded data.
  • sslkey - Key file location. The file must contain PEM encoded data.
  • sslrootcert - The location of the root certificate file. The file must contain PEM encoded data.

Valid values for sslmode are:

  • disable - No SSL
  • require - Always SSL (skip verification)
  • verify-ca - Always SSL (verify that the certificate presented by the server was signed by a trusted CA)
  • verify-full - Always SSL (verify that the certification presented by the server was signed by a trusted CA and the server host name matches the one in the certificate)

See http://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING for more information about connection string parameters.

Use single quotes for values that contain whitespace: 

"user=pqgotest password='with spaces'"

A backslash will escape the next character in values: 

"user=space\ man password='it\'s valid'"

Note that the connection parameter client_encoding (which sets the text encoding for the connection) may be set but must be "UTF8", matching with the same rules as Postgres. It is an error to provide any other value.

In addition to the parameters listed above, any run-time parameter that can be set at backend start time can be set in the connection string. For more information, see http://www.postgresql.org/docs/current/static/runtime-config.html.

Most environment variables as specified at http://www.postgresql.org/docs/current/static/libpq-envars.html supported by libpq are also supported by pq. If any of the environment variables not supported by pq are set, pq will panic during connection establishment. Environment variables have a lower precedence than explicitly provided connection parameters.

The pgpass mechanism as described in http://www.postgresql.org/docs/current/static/libpq-pgpass.html is supported, but on Windows PGPASSFILE must be specified explicitly.

Queries

database/sql does not dictate any specific format for parameter markers in query strings, and pq uses the Postgres-native ordinal markers, as shown above. The same marker can be reused for the same parameter: 

rows, err := db.Query(`SELECT name FROM users WHERE favorite_fruit = $1
	OR age BETWEEN $2 AND $2 + 3`, "orange", 64)

pq does not support the LastInsertId() method of the Result type in database/sql. To return the identifier of an INSERT (or UPDATE or DELETE), use the Postgres RETURNING clause with a standard Query or QueryRow call: 

var userid int
err := db.QueryRow(`INSERT INTO users(name, favorite_fruit, age)
	VALUES('beatrice', 'starfruit', 93) RETURNING id`).Scan(&userid)

For more details on RETURNING, see the Postgres documentation: 

http://www.postgresql.org/docs/current/static/sql-insert.html
http://www.postgresql.org/docs/current/static/sql-update.html
http://www.postgresql.org/docs/current/static/sql-delete.html

For additional instructions on querying see the documentation for the database/sql package.

Data Types

Parameters pass through driver.DefaultParameterConverter before they are handled by this package. When the binary_parameters connection option is enabled, []byte values are sent directly to the backend as data in binary format.

This package returns the following types for values from the PostgreSQL backend:

  • integer types smallint, integer, and bigint are returned as int64
  • floating-point types real and double precision are returned as float64
  • character types char, varchar, and text are returned as string
  • temporal types date, time, timetz, timestamp, and timestamptz are returned as time.Time
  • the boolean type is returned as bool
  • the bytea type is returned as []byte

All other types are returned directly from the backend as []byte values in text format.

Errors

pq may return errors of type *pq.Error which can be interrogated for error details: 

if err, ok := err.(*pq.Error); ok {
    fmt.Println("pq error:", err.Code.Name())
}

See the pq.Error type for details.

Bulk imports

You can perform bulk imports by preparing a statement returned by pq.CopyIn (or pq.CopyInSchema) in an explicit transaction (sql.Tx). The returned statement handle can then be repeatedly "executed" to copy data into the target table. After all data has been processed you should call Exec() once with no arguments to flush all buffered data. Any call to Exec() might return an error which should be handled appropriately, but because of the internal buffering an error returned by Exec() might not be related to the data passed in the call that failed.

CopyIn uses COPY FROM internally. It is not possible to COPY outside of an explicit transaction in pq.

Usage example: 

txn, err := db.Begin()
if err != nil {
	log.Fatal(err)
}

stmt, err := txn.Prepare(pq.CopyIn("users", "name", "age"))
if err != nil {
	log.Fatal(err)
}

for _, user := range users {
	_, err = stmt.Exec(user.Name, int64(user.Age))
	if err != nil {
		log.Fatal(err)
	}
}

_, err = stmt.Exec()
if err != nil {
	log.Fatal(err)
}

err = stmt.Close()
if err != nil {
	log.Fatal(err)
}

err = txn.Commit()
if err != nil {
	log.Fatal(err)
}

Notifications

PostgreSQL supports a simple publish/subscribe model over database connections. See http://www.postgresql.org/docs/current/static/sql-notify.html for more information about the general mechanism.

To start listening for notifications, you first have to open a new connection to the database by calling NewListener. This connection can not be used for anything other than LISTEN / NOTIFY. Calling Listen will open a "notification channel"; once a notification channel is open, a notification generated on that channel will effect a send on the Listener.Notify channel. A notification channel will remain open until Unlisten is called, though connection loss might result in some notifications being lost. To solve this problem, Listener sends a nil pointer over the Notify channel any time the connection is re-established following a connection loss. The application can get information about the state of the underlying connection by setting an event callback in the call to NewListener.

A single Listener can safely be used from concurrent goroutines, which means that there is often no need to create more than one Listener in your application. However, a Listener is always connected to a single database, so you will need to create a new Listener instance for every database you want to receive notifications in.

The channel name in both Listen and Unlisten is case sensitive, and can contain any characters legal in an identifier (see http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS for more information). Note that the channel name will be truncated to 63 bytes by the PostgreSQL server.

You can find a complete, working example of Listener usage at https://godoc.org/github.com/lib/pq/example/listen.

Kerberos Support

If you need support for Kerberos authentication, add the following to your main package: 

import "github.com/lib/pq/auth/kerberos"

func init() {
	pq.RegisterGSSProvider(func() (pq.Gss, error) { return kerberos.NewGSS() })
}

This package is in a separate module so that users who don't need Kerberos don't have to download unnecessary dependencies.

When imported, additional connection string parameters are supported:

  • krbsrvname - GSS (Kerberos) service name when constructing the SPN (default is `postgres`). This will be combined with the host to form the full SPN: `krbsrvname/host`.
  • krbspn - GSS (Kerberos) SPN. This takes priority over `krbsrvname` if present.

Index ▾

Constants
Variables
func Array(a interface{}) interface {driver.Valuer sql.Scanner}
func BufferQuoteIdentifier(name string, buffer *bytes.Buffer)
func ConnectorNoticeHandler(c driver.Connector) func(*Error)
func ConnectorNotificationHandler(c driver.Connector) func(*Notification)
func CopyIn(table string, columns ...string) string
func CopyInSchema(schema, table string, columns ...string) string
func DialOpen(d Dialer, dsn string) (_ driver.Conn, err error)
func EnableInfinityTs(negative time.Time, positive time.Time)
func FormatTimestamp(t time.Time) []byte
func NoticeHandler(c driver.Conn) func(*Error)
func Open(dsn string) (_ driver.Conn, err error)
func ParseTimestamp(currentLocation *time.Location, str string) (time.Time, error)
func ParseURL(url string) (string, error)
func QuoteIdentifier(name string) string
func QuoteLiteral(literal string) string
func RegisterGSSProvider(newGssArg NewGSSFunc)
func SetNoticeHandler(c driver.Conn, handler func(*Error))
func SetNotificationHandler(c driver.Conn, handler func(*Notification))
type ArrayDelimiter
type BoolArray
    func (a *BoolArray) Scan(src interface{}) error
    func (a BoolArray) Value() (driver.Value, error)
type ByteaArray
    func (a *ByteaArray) Scan(src interface{}) error
    func (a ByteaArray) Value() (driver.Value, error)
type Connector
    func NewConnector(dsn string) (*Connector, error)
    func (c *Connector) Connect(ctx context.Context) (driver.Conn, error)
    func (c *Connector) Dialer(dialer Dialer)
    func (c *Connector) Driver() driver.Driver
type Dialer
type DialerContext
type Driver
    func (d Driver) Open(name string) (driver.Conn, error)
type Error
    func (err *Error) Error() string
    func (err *Error) Fatal() bool
    func (err *Error) Get(k byte) (v string)
    func (err *Error) SQLState() string
type ErrorClass
    func (ec ErrorClass) Name() string
type ErrorCode
    func (ec ErrorCode) Class() ErrorClass
    func (ec ErrorCode) Name() string
type EventCallbackType
type Float32Array
    func (a *Float32Array) Scan(src interface{}) error
    func (a Float32Array) Value() (driver.Value, error)
type Float64Array
    func (a *Float64Array) Scan(src interface{}) error
    func (a Float64Array) Value() (driver.Value, error)
type GSS
type GenericArray
    func (a GenericArray) Scan(src interface{}) error
    func (a GenericArray) Value() (driver.Value, error)
type Int32Array
    func (a *Int32Array) Scan(src interface{}) error
    func (a Int32Array) Value() (driver.Value, error)
type Int64Array
    func (a *Int64Array) Scan(src interface{}) error
    func (a Int64Array) Value() (driver.Value, error)
type Listener
    func NewDialListener(d Dialer, name string, minReconnectInterval time.Duration, maxReconnectInterval time.Duration, eventCallback EventCallbackType) *Listener
    func NewListener(name string, minReconnectInterval time.Duration, maxReconnectInterval time.Duration, eventCallback EventCallbackType) *Listener
    func (l *Listener) Close() error
    func (l *Listener) Listen(channel string) error
    func (l *Listener) NotificationChannel() <-chan *Notification
    func (l *Listener) Ping() error
    func (l *Listener) Unlisten(channel string) error
    func (l *Listener) UnlistenAll() error
type ListenerConn
    func NewListenerConn(name string, notificationChan chan<- *Notification) (*ListenerConn, error)
    func (l *ListenerConn) Close() error
    func (l *ListenerConn) Err() error
    func (l *ListenerConn) ExecSimpleQuery(q string) (executed bool, err error)
    func (l *ListenerConn) Listen(channel string) (bool, error)
    func (l *ListenerConn) Ping() error
    func (l *ListenerConn) Unlisten(channel string) (bool, error)
    func (l *ListenerConn) UnlistenAll() (bool, error)
type ListenerEventType
type NewGSSFunc
type NoticeHandlerConnector
    func ConnectorWithNoticeHandler(c driver.Connector, handler func(*Error)) *NoticeHandlerConnector
    func (n *NoticeHandlerConnector) Connect(ctx context.Context) (driver.Conn, error)
type Notification
type NotificationHandlerConnector
    func ConnectorWithNotificationHandler(c driver.Connector, handler func(*Notification)) *NotificationHandlerConnector
    func (n *NotificationHandlerConnector) Connect(ctx context.Context) (driver.Conn, error)
type NullTime
    func (nt *NullTime) Scan(value interface{}) error
    func (nt NullTime) Value() (driver.Value, error)
type PGError
type StringArray
    func (a *StringArray) Scan(src interface{}) error
    func (a StringArray) Value() (driver.Value, error)

Package files

array.go buf.go conn.go conn_go115.go conn_go18.go connector.go copy.go doc.go encode.go error.go krb.go notice.go notify.go rows.go ssl.go ssl_permissions.go url.go user_posix.go uuid.go

Constants

Error severities 

const (
    Efatal   = "FATAL"
    Epanic   = "PANIC"
    Ewarning = "WARNING"
    Enotice  = "NOTICE"
    Edebug   = "DEBUG"
    Einfo    = "INFO"
    Elog     = "LOG"
)

Variables

Common error types 

var (
    ErrNotSupported              = errors.New("pq: Unsupported command")
    ErrInFailedTransaction       = errors.New("pq: Could not complete operation in a failed transaction")
    ErrSSLNotSupported           = errors.New("pq: SSL is not enabled on the server")
    ErrSSLKeyUnknownOwnership    = errors.New("pq: Could not get owner information for private key, may not be properly protected")
    ErrSSLKeyHasWorldPermissions = errors.New("pq: Private key has world access. Permissions should be u=rw,g=r (0640) if owned by root, or u=rw (0600), or less")

    ErrCouldNotDetectUsername = errors.New("pq: Could not detect default username. Please provide one explicitly")
)

ErrChannelAlreadyOpen is returned from Listen when a channel is already open. 

var ErrChannelAlreadyOpen = errors.New("pq: channel is already open")

ErrChannelNotOpen is returned from Unlisten when a channel is not open. 

var ErrChannelNotOpen = errors.New("pq: channel is not open")

func Array 

func Array(a interface{}) interface {
    driver.Valuer
    sql.Scanner
}

Array returns the optimal driver.Valuer and sql.Scanner for an array or slice of any dimension.

For example: 

db.Query(`SELECT * FROM t WHERE id = ANY($1)`, pq.Array([]int{235, 401}))

var x []sql.NullInt64
db.QueryRow(`SELECT ARRAY[235, 401]`).Scan(pq.Array(&x))

Scanning multi-dimensional arrays is not supported. Arrays where the lower bound is not one (such as `[0:0]={1}') are not supported.

func BufferQuoteIdentifier 

func BufferQuoteIdentifier(name string, buffer *bytes.Buffer)

BufferQuoteIdentifier satisfies the same purpose as QuoteIdentifier, but backed by a byte buffer.

func ConnectorNoticeHandler 

func ConnectorNoticeHandler(c driver.Connector) func(*Error)

ConnectorNoticeHandler returns the currently set notice handler, if any. If the given connector is not a result of ConnectorWithNoticeHandler, nil is returned.

func ConnectorNotificationHandler 

func ConnectorNotificationHandler(c driver.Connector) func(*Notification)

ConnectorNotificationHandler returns the currently set notification handler, if any. If the given connector is not a result of ConnectorWithNotificationHandler, nil is returned.

func CopyIn 

func CopyIn(table string, columns ...string) string

CopyIn creates a COPY FROM statement which can be prepared with Tx.Prepare(). The target table should be visible in search_path.

func CopyInSchema 

func CopyInSchema(schema, table string, columns ...string) string

CopyInSchema creates a COPY FROM statement which can be prepared with Tx.Prepare().

func DialOpen 

func DialOpen(d Dialer, dsn string) (_ driver.Conn, err error)

DialOpen opens a new connection to the database using a dialer.

func EnableInfinityTs 

func EnableInfinityTs(negative time.Time, positive time.Time)

EnableInfinityTs controls the handling of Postgres' "-infinity" and "infinity" "timestamp"s.

If EnableInfinityTs is not called, "-infinity" and "infinity" will return []byte("-infinity") and []byte("infinity") respectively, and potentially cause error "sql: Scan error on column index 0: unsupported driver -> Scan pair: []uint8 -> *time.Time", when scanning into a time.Time value.

Once EnableInfinityTs has been called, all connections created using this driver will decode Postgres' "-infinity" and "infinity" for "timestamp", "timestamp with time zone" and "date" types to the predefined minimum and maximum times, respectively. When encoding time.Time values, any time which equals or precedes the predefined minimum time will be encoded to "-infinity". Any values at or past the maximum time will similarly be encoded to "infinity".

If EnableInfinityTs is called with negative >= positive, it will panic. Calling EnableInfinityTs after a connection has been established results in undefined behavior. If EnableInfinityTs is called more than once, it will panic.

func FormatTimestamp 

func FormatTimestamp(t time.Time) []byte

FormatTimestamp formats t into Postgres' text format for timestamps.

func NoticeHandler 

func NoticeHandler(c driver.Conn) func(*Error)

NoticeHandler returns the notice handler on the given connection, if any. A runtime panic occurs if c is not a pq connection. This is rarely used directly, use ConnectorNoticeHandler and ConnectorWithNoticeHandler instead.

func Open 

func Open(dsn string) (_ driver.Conn, err error)

Open opens a new connection to the database. dsn is a connection string. Most users should only use it through database/sql package from the standard library.

func ParseTimestamp 

func ParseTimestamp(currentLocation *time.Location, str string) (time.Time, error)

ParseTimestamp parses Postgres' text format. It returns a time.Time in currentLocation iff that time's offset agrees with the offset sent from the Postgres server. Otherwise, ParseTimestamp returns a time.Time with the fixed offset offset provided by the Postgres server.

func ParseURL 

func ParseURL(url string) (string, error)

ParseURL no longer needs to be used by clients of this library since supplying a URL as a connection string to sql.Open() is now supported: 

sql.Open("postgres", "postgres://bob:secret@1.2.3.4:5432/mydb?sslmode=verify-full")

It remains exported here for backwards-compatibility.

ParseURL converts a url to a connection string for driver.Open. Example: 

"postgres://bob:secret@1.2.3.4:5432/mydb?sslmode=verify-full"

converts to: 

"user=bob password=secret host=1.2.3.4 port=5432 dbname=mydb sslmode=verify-full"

A minimal example: 

"postgres://"

This will be blank, causing driver.Open to use all of the defaults

func QuoteIdentifier 

func QuoteIdentifier(name string) string

QuoteIdentifier quotes an "identifier" (e.g. a table or a column name) to be used as part of an SQL statement. For example: 

tblname := "my_table"
data := "my_data"
quoted := pq.QuoteIdentifier(tblname)
err := db.Exec(fmt.Sprintf("INSERT INTO %s VALUES ($1)", quoted), data)

Any double quotes in name will be escaped. The quoted identifier will be case sensitive when used in a query. If the input string contains a zero byte, the result will be truncated immediately before it.

func QuoteLiteral 

func QuoteLiteral(literal string) string

QuoteLiteral quotes a 'literal' (e.g. a parameter, often used to pass literal to DDL and other statements that do not accept parameters) to be used as part of an SQL statement. For example: 

exp_date := pq.QuoteLiteral("2023-01-05 15:00:00Z")
err := db.Exec(fmt.Sprintf("CREATE ROLE my_user VALID UNTIL %s", exp_date))

Any single quotes in name will be escaped. Any backslashes (i.e. "\") will be replaced by two backslashes (i.e. "\\") and the C-style escape identifier that PostgreSQL provides ('E') will be prepended to the string.

func RegisterGSSProvider 

func RegisterGSSProvider(newGssArg NewGSSFunc)

RegisterGSSProvider registers a GSS authentication provider. For example, if you need to use Kerberos to authenticate with your server, add this to your main package: 

import "github.com/lib/pq/auth/kerberos"

func init() {
	pq.RegisterGSSProvider(func() (pq.GSS, error) { return kerberos.NewGSS() })
}

func SetNoticeHandler 

func SetNoticeHandler(c driver.Conn, handler func(*Error))

SetNoticeHandler sets the given notice handler on the given connection. A runtime panic occurs if c is not a pq connection. A nil handler may be used to unset it. This is rarely used directly, use ConnectorNoticeHandler and ConnectorWithNoticeHandler instead.

Note: Notice handlers are executed synchronously by pq meaning commands won't continue to be processed until the handler returns.

func SetNotificationHandler 

func SetNotificationHandler(c driver.Conn, handler func(*Notification))

SetNotificationHandler sets the given notification handler on the given connection. A runtime panic occurs if c is not a pq connection. A nil handler may be used to unset it.

Note: Notification handlers are executed synchronously by pq meaning commands won't continue to be processed until the handler returns.

type ArrayDelimiter

ArrayDelimiter may be optionally implemented by driver.Valuer or sql.Scanner to override the array delimiter used by GenericArray. 

type ArrayDelimiter interface {
    // ArrayDelimiter returns the delimiter character(s) for this element's type.
    ArrayDelimiter() string
}

type BoolArray

BoolArray represents a one-dimensional array of the PostgreSQL boolean type. 

type BoolArray []bool

func (*BoolArray) Scan 

func (a *BoolArray) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (BoolArray) Value 

func (a BoolArray) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type ByteaArray

ByteaArray represents a one-dimensional array of the PostgreSQL bytea type. 

type ByteaArray [][]byte

func (*ByteaArray) Scan 

func (a *ByteaArray) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (ByteaArray) Value 

func (a ByteaArray) Value() (driver.Value, error)

Value implements the driver.Valuer interface. It uses the "hex" format which is only supported on PostgreSQL 9.0 or newer.

type Connector

Connector represents a fixed configuration for the pq driver with a given name. Connector satisfies the database/sql/driver Connector interface and can be used to create any number of DB Conn's via the database/sql OpenDB function.

See https://golang.org/pkg/database/sql/driver/#Connector. See https://golang.org/pkg/database/sql/#OpenDB. 

type Connector struct {
    // contains filtered or unexported fields
}

func NewConnector 

func NewConnector(dsn string) (*Connector, error)

NewConnector returns a connector for the pq driver in a fixed configuration with the given dsn. The returned connector can be used to create any number of equivalent Conn's. The returned connector is intended to be used with database/sql.OpenDB.

See https://golang.org/pkg/database/sql/driver/#Connector. See https://golang.org/pkg/database/sql/#OpenDB.

▾ Example

Code:

name := ""
connector, err := pq.NewConnector(name)
if err != nil {
    fmt.Println(err)
    return
}
db := sql.OpenDB(connector)
defer db.Close()

// Use the DB
txn, err := db.Begin()
if err != nil {
    fmt.Println(err)
    return
}
txn.Rollback()

func (*Connector) Connect 

func (c *Connector) Connect(ctx context.Context) (driver.Conn, error)

Connect returns a connection to the database using the fixed configuration of this Connector. Context is not used.

func (*Connector) Dialer 

func (c *Connector) Dialer(dialer Dialer)

Dialer allows change the dialer used to open connections.

func (*Connector) Driver 

func (c *Connector) Driver() driver.Driver

Driver returns the underlying driver of this Connector.

type Dialer

Dialer is the dialer interface. It can be used to obtain more control over how pq creates network connections. 

type Dialer interface {
    Dial(network, address string) (net.Conn, error)
    DialTimeout(network, address string, timeout time.Duration) (net.Conn, error)
}

type DialerContext

DialerContext is the context-aware dialer interface. 

type DialerContext interface {
    DialContext(ctx context.Context, network, address string) (net.Conn, error)
}

type Driver

Driver is the Postgres database driver. 

type Driver struct{}

func (Driver) Open 

func (d Driver) Open(name string) (driver.Conn, error)

Open opens a new connection to the database. name is a connection string. Most users should only use it through database/sql package from the standard library.

type Error

Error represents an error communicating with the server.

See http://www.postgresql.org/docs/current/static/protocol-error-fields.html for details of the fields 

type Error struct {
    Severity         string
    Code             ErrorCode
    Message          string
    Detail           string
    Hint             string
    Position         string
    InternalPosition string
    InternalQuery    string
    Where            string
    Schema           string
    Table            string
    Column           string
    DataTypeName     string
    Constraint       string
    File             string
    Line             string
    Routine          string
}

func (*Error) Error 

func (err *Error) Error() string

func (*Error) Fatal 

func (err *Error) Fatal() bool

Fatal returns true if the Error Severity is fatal.

func (*Error) Get 

func (err *Error) Get(k byte) (v string)

Get implements the legacy PGError interface. New code should use the fields of the Error struct directly.

func (*Error) SQLState 

func (err *Error) SQLState() string

SQLState returns the SQLState of the error.

type ErrorClass

ErrorClass is only the class part of an error code. 

type ErrorClass string

func (ErrorClass) Name 

func (ec ErrorClass) Name() string

Name returns the condition name of an error class. It is equivalent to the condition name of the "standard" error code (i.e. the one having the last three characters "000").

type ErrorCode

ErrorCode is a five-character error code. 

type ErrorCode string

func (ErrorCode) Class 

func (ec ErrorCode) Class() ErrorClass

Class returns the error class, e.g. "28".

See http://www.postgresql.org/docs/9.3/static/errcodes-appendix.html for details.

func (ErrorCode) Name 

func (ec ErrorCode) Name() string

Name returns a more human friendly rendering of the error code, namely the "condition name".

See http://www.postgresql.org/docs/9.3/static/errcodes-appendix.html for details.

type EventCallbackType

EventCallbackType is the event callback type. See also ListenerEventType constants' documentation. 

type EventCallbackType func(event ListenerEventType, err error)

type Float32Array

Float32Array represents a one-dimensional array of the PostgreSQL double precision type. 

type Float32Array []float32

func (*Float32Array) Scan 

func (a *Float32Array) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (Float32Array) Value 

func (a Float32Array) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type Float64Array

Float64Array represents a one-dimensional array of the PostgreSQL double precision type. 

type Float64Array []float64

func (*Float64Array) Scan 

func (a *Float64Array) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (Float64Array) Value 

func (a Float64Array) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type GSS

GSS provides GSSAPI authentication (e.g., Kerberos). 

type GSS interface {
    GetInitToken(host string, service string) ([]byte, error)
    GetInitTokenFromSpn(spn string) ([]byte, error)
    Continue(inToken []byte) (done bool, outToken []byte, err error)
}

type GenericArray

GenericArray implements the driver.Valuer and sql.Scanner interfaces for an array or slice of any dimension. 

type GenericArray struct{ A interface{} }

func (GenericArray) Scan 

func (a GenericArray) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (GenericArray) Value 

func (a GenericArray) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type Int32Array

Int32Array represents a one-dimensional array of the PostgreSQL integer types. 

type Int32Array []int32

func (*Int32Array) Scan 

func (a *Int32Array) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (Int32Array) Value 

func (a Int32Array) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type Int64Array

Int64Array represents a one-dimensional array of the PostgreSQL integer types. 

type Int64Array []int64

func (*Int64Array) Scan 

func (a *Int64Array) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (Int64Array) Value 

func (a Int64Array) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

type Listener

Listener provides an interface for listening to notifications from a PostgreSQL database. For general usage information, see section "Notifications".

Listener can safely be used from concurrently running goroutines. 

type Listener struct {
    // Channel for receiving notifications from the database.  In some cases a
    // nil value will be sent.  See section "Notifications" above.
    Notify chan *Notification
    // contains filtered or unexported fields
}

func NewDialListener 

func NewDialListener(d Dialer,
    name string,
    minReconnectInterval time.Duration,
    maxReconnectInterval time.Duration,
    eventCallback EventCallbackType) *Listener

NewDialListener is like NewListener but it takes a Dialer.

func NewListener 

func NewListener(name string,
    minReconnectInterval time.Duration,
    maxReconnectInterval time.Duration,
    eventCallback EventCallbackType) *Listener

NewListener creates a new database connection dedicated to LISTEN / NOTIFY.

name should be set to a connection string to be used to establish the database connection (see section "Connection String Parameters" above).

minReconnectInterval controls the duration to wait before trying to re-establish the database connection after connection loss. After each consecutive failure this interval is doubled, until maxReconnectInterval is reached. Successfully completing the connection establishment procedure resets the interval back to minReconnectInterval.

The last parameter eventCallback can be set to a function which will be called by the Listener when the state of the underlying database connection changes. This callback will be called by the goroutine which dispatches the notifications over the Notify channel, so you should try to avoid doing potentially time-consuming operations from the callback.

func (*Listener) Close 

func (l *Listener) Close() error

Close disconnects the Listener from the database and shuts it down. Subsequent calls to its methods will return an error. Close returns an error if the connection has already been closed.

func (*Listener) Listen 

func (l *Listener) Listen(channel string) error

Listen starts listening for notifications on a channel. Calls to this function will block until an acknowledgement has been received from the server. Note that Listener automatically re-establishes the connection after connection loss, so this function may block indefinitely if the connection can not be re-established.

Listen will only fail in three conditions:

  1. The channel is already open. The returned error will be ErrChannelAlreadyOpen.
  2. The query was executed on the remote server, but PostgreSQL returned an error message in response to the query. The returned error will be a pq.Error containing the information the server supplied.
  3. Close is called on the Listener before the request could be completed.

The channel name is case-sensitive.

func (*Listener) NotificationChannel 

func (l *Listener) NotificationChannel() <-chan *Notification

NotificationChannel returns the notification channel for this listener. This is the same channel as Notify, and will not be recreated during the life time of the Listener.

func (*Listener) Ping 

func (l *Listener) Ping() error

Ping the remote server to make sure it's alive. Non-nil return value means that there is no active connection.

func (*Listener) Unlisten 

func (l *Listener) Unlisten(channel string) error

Unlisten removes a channel from the Listener's channel list. Returns ErrChannelNotOpen if the Listener is not listening on the specified channel. Returns immediately with no error if there is no connection. Note that you might still get notifications for this channel even after Unlisten has returned.

The channel name is case-sensitive.

func (*Listener) UnlistenAll 

func (l *Listener) UnlistenAll() error

UnlistenAll removes all channels from the Listener's channel list. Returns immediately with no error if there is no connection. Note that you might still get notifications for any of the deleted channels even after UnlistenAll has returned.

type ListenerConn

ListenerConn is a low-level interface for waiting for notifications. You should use Listener instead. 

type ListenerConn struct {
    // contains filtered or unexported fields
}

func NewListenerConn 

func NewListenerConn(name string, notificationChan chan<- *Notification) (*ListenerConn, error)

NewListenerConn creates a new ListenerConn. Use NewListener instead.

func (*ListenerConn) Close 

func (l *ListenerConn) Close() error

Close closes the connection.

func (*ListenerConn) Err 

func (l *ListenerConn) Err() error

Err returns the reason the connection was closed. It is not safe to call this function until l.Notify has been closed.

func (*ListenerConn) ExecSimpleQuery 

func (l *ListenerConn) ExecSimpleQuery(q string) (executed bool, err error)

ExecSimpleQuery executes a "simple query" (i.e. one with no bindable parameters) on the connection. The possible return values are:

  1. "executed" is true; the query was executed to completion on the database server. If the query failed, err will be set to the error returned by the database, otherwise err will be nil.
  2. If "executed" is false, the query could not be executed on the remote server. err will be non-nil.

After a call to ExecSimpleQuery has returned an executed=false value, the connection has either been closed or will be closed shortly thereafter, and all subsequently executed queries will return an error.

func (*ListenerConn) Listen 

func (l *ListenerConn) Listen(channel string) (bool, error)

Listen sends a LISTEN query to the server. See ExecSimpleQuery.

func (*ListenerConn) Ping 

func (l *ListenerConn) Ping() error

Ping the remote server to make sure it's alive. Non-nil error means the connection has failed and should be abandoned.

func (*ListenerConn) Unlisten 

func (l *ListenerConn) Unlisten(channel string) (bool, error)

Unlisten sends an UNLISTEN query to the server. See ExecSimpleQuery.

func (*ListenerConn) UnlistenAll 

func (l *ListenerConn) UnlistenAll() (bool, error)

UnlistenAll sends an `UNLISTEN *` query to the server. See ExecSimpleQuery.

type ListenerEventType

ListenerEventType is an enumeration of listener event types. 

type ListenerEventType int
const (
    // ListenerEventConnected is emitted only when the database connection
    // has been initially initialized. The err argument of the callback
    // will always be nil.
    ListenerEventConnected ListenerEventType = iota

    // ListenerEventDisconnected is emitted after a database connection has
    // been lost, either because of an error or because Close has been
    // called. The err argument will be set to the reason the database
    // connection was lost.
    ListenerEventDisconnected

    // ListenerEventReconnected is emitted after a database connection has
    // been re-established after connection loss. The err argument of the
    // callback will always be nil. After this event has been emitted, a
    // nil pq.Notification is sent on the Listener.Notify channel.
    ListenerEventReconnected

    // ListenerEventConnectionAttemptFailed is emitted after a connection
    // to the database was attempted, but failed. The err argument will be
    // set to an error describing why the connection attempt did not
    // succeed.
    ListenerEventConnectionAttemptFailed
)

type NewGSSFunc

NewGSSFunc creates a GSS authentication provider, for use with RegisterGSSProvider. 

type NewGSSFunc func() (GSS, error)

type NoticeHandlerConnector

NoticeHandlerConnector wraps a regular connector and sets a notice handler on it. 

type NoticeHandlerConnector struct {
    driver.Connector
    // contains filtered or unexported fields
}

func ConnectorWithNoticeHandler 

func ConnectorWithNoticeHandler(c driver.Connector, handler func(*Error)) *NoticeHandlerConnector

ConnectorWithNoticeHandler creates or sets the given handler for the given connector. If the given connector is a result of calling this function previously, it is simply set on the given connector and returned. Otherwise, this returns a new connector wrapping the given one and setting the notice handler. A nil notice handler may be used to unset it.

The returned connector is intended to be used with database/sql.OpenDB.

Note: Notice handlers are executed synchronously by pq meaning commands won't continue to be processed until the handler returns.

▾ Example

Code:

name := ""
// Base connector to wrap
base, err := pq.NewConnector(name)
if err != nil {
    log.Fatal(err)
}
// Wrap the connector to simply print out the message
connector := pq.ConnectorWithNoticeHandler(base, func(notice *pq.Error) {
    fmt.Println("Notice sent: " + notice.Message)
})
db := sql.OpenDB(connector)
defer db.Close()
// Raise a notice
sql := "DO language plpgsql $$ BEGIN RAISE NOTICE 'test notice'; END $$"
if _, err := db.Exec(sql); err != nil {
    log.Fatal(err)
}

Output:

Notice sent: test notice

func (*NoticeHandlerConnector) Connect 

func (n *NoticeHandlerConnector) Connect(ctx context.Context) (driver.Conn, error)

Connect calls the underlying connector's connect method and then sets the notice handler.

type Notification

Notification represents a single notification from the database. 

type Notification struct {
    // Process ID (PID) of the notifying postgres backend.
    BePid int
    // Name of the channel the notification was sent on.
    Channel string
    // Payload, or the empty string if unspecified.
    Extra string
}

type NotificationHandlerConnector

NotificationHandlerConnector wraps a regular connector and sets a notification handler on it. 

type NotificationHandlerConnector struct {
    driver.Connector
    // contains filtered or unexported fields
}

func ConnectorWithNotificationHandler 

func ConnectorWithNotificationHandler(c driver.Connector, handler func(*Notification)) *NotificationHandlerConnector

ConnectorWithNotificationHandler creates or sets the given handler for the given connector. If the given connector is a result of calling this function previously, it is simply set on the given connector and returned. Otherwise, this returns a new connector wrapping the given one and setting the notification handler. A nil notification handler may be used to unset it.

The returned connector is intended to be used with database/sql.OpenDB.

Note: Notification handlers are executed synchronously by pq meaning commands won't continue to be processed until the handler returns.

func (*NotificationHandlerConnector) Connect 

func (n *NotificationHandlerConnector) Connect(ctx context.Context) (driver.Conn, error)

Connect calls the underlying connector's connect method and then sets the notification handler.

type NullTime

NullTime represents a time.Time that may be null. NullTime implements the sql.Scanner interface so it can be used as a scan destination, similar to sql.NullString. 

type NullTime struct {
    Time  time.Time
    Valid bool // Valid is true if Time is not NULL
}

func (*NullTime) Scan 

func (nt *NullTime) Scan(value interface{}) error

Scan implements the Scanner interface.

func (NullTime) Value 

func (nt NullTime) Value() (driver.Value, error)

Value implements the driver Valuer interface.

type PGError

PGError is an interface used by previous versions of pq. It is provided only to support legacy code. New code should use the Error type. 

type PGError interface {
    Error() string
    Fatal() bool
    Get(k byte) (v string)
}

type StringArray

StringArray represents a one-dimensional array of the PostgreSQL character types. 

type StringArray []string

func (*StringArray) Scan 

func (a *StringArray) Scan(src interface{}) error

Scan implements the sql.Scanner interface.

func (StringArray) Value 

func (a StringArray) Value() (driver.Value, error)

Value implements the driver.Valuer interface.

Subdirectories

Name Synopsis
..
example
listen Package listen is a self-contained Go program which uses the LISTEN / NOTIFY mechanism to avoid polling the database while waiting for more work to arrive.
hstore
oid Package oid contains OID constants as defined by the Postgres server.
scram Package scram implements a SCRAM-{SHA-1,etc} client per RFC5802.