Table of Contents

Class NpgsqlConnection

Namespace
Npgsql
Assembly
Npgsql.dll

This class represents a connection to a PostgreSQL server.

public sealed class NpgsqlConnection : DbConnection, IComponent, IDbConnection, IDisposable, IAsyncDisposable, ICloneable
Inheritance
NpgsqlConnection
Implements
Inherited Members

Constructors

NpgsqlConnection()

Initializes a new instance of the NpgsqlConnection class.

public NpgsqlConnection()

NpgsqlConnection(string)

Initializes a new instance of NpgsqlConnection with the given connection string.

public NpgsqlConnection(string connectionString)

Parameters

connectionString string

The connection used to open the PostgreSQL database.

Fields

DefaultPort

The default TCP/IP port for PostgreSQL.

public const int DefaultPort = 5432

Field Value

int

Properties

CommandTimeout

Gets the time to wait while trying to execute a command before terminating the attempt and generating an error.

public int CommandTimeout { get; }

Property Value

int

The time (in seconds) to wait for a command to complete. The default value is 20 seconds.

ConnectionString

Gets or sets the string used to connect to a PostgreSQL database. See the manual for details.

public override string ConnectionString { get; set; }

Property Value

string

The connection string that includes the server name, the database name, and other parameters needed to establish the initial connection. The default value is an empty string.

ConnectionTimeout

Gets the time to wait while trying to establish a connection before terminating the attempt and generating an error.

public override int ConnectionTimeout { get; }

Property Value

int

The time (in seconds) to wait for a connection to open. The default value is 15 seconds.

DataSource

Gets the string identifying the database server (host and port)

public override string DataSource { get; }

Property Value

string

Database

Gets the name of the current database or the database to be used after a connection is opened.

public override string Database { get; }

Property Value

string

The name of the current database or the name of the database to be used after a connection is opened. The default value is the empty string.

DbProviderFactory

DB provider factory.

protected override DbProviderFactory DbProviderFactory { get; }

Property Value

DbProviderFactory

FullState

Gets the current state of the connection.

[Browsable(false)]
public ConnectionState FullState { get; }

Property Value

ConnectionState

A bitwise combination of the ConnectionState values. The default is Closed.

GlobalTypeMapper

The global type mapper, which contains defaults used by all new connections. Modify mappings on this mapper to affect your entire application.

public static INpgsqlTypeMapper GlobalTypeMapper { get; }

Property Value

INpgsqlTypeMapper

HasIntegerDateTimes

Reports whether the backend uses the newer integer timestamp representation. Note that the old floating point representation is not supported. Meant for use by type plugins (e.g. Nodatime)

[Browsable(false)]
public bool HasIntegerDateTimes { get; }

Property Value

bool

Host

Backend server host name.

[Browsable(true)]
public string Host { get; }

Property Value

string

IntegratedSecurity

Whether to use Windows integrated security to log in.

public bool IntegratedSecurity { get; }

Property Value

bool

Port

Backend server port.

[Browsable(true)]
public int Port { get; }

Property Value

int

PostgreSqlVersion

Version of the PostgreSQL backend. This can only be called when there is an active connection.

[Browsable(false)]
public Version PostgreSqlVersion { get; }

Property Value

Version

PostgresParameters

Holds all PostgreSQL parameters received for this connection. Is updated if the values change (e.g. as a result of a SET command).

[Browsable(false)]
public IReadOnlyDictionary<string, string> PostgresParameters { get; }

Property Value

IReadOnlyDictionary<string, string>

ProcessID

Process id of backend server. This can only be called when there is an active connection.

[Browsable(false)]
public int ProcessID { get; }

Property Value

int

ProvideClientCertificatesCallback

Selects the local Secure Sockets Layer (SSL) certificate used for authentication.

public ProvideClientCertificatesCallback ProvideClientCertificatesCallback { get; set; }

Property Value

ProvideClientCertificatesCallback

Remarks

See https://msdn.microsoft.com/en-us/library/system.net.security.localcertificateselectioncallback(v=vs.110).aspx

ServerVersion

PostgreSQL server version.

public override string ServerVersion { get; }

Property Value

string

State

Gets whether the current state of the connection is Open or Closed

[Browsable(false)]
public override ConnectionState State { get; }

Property Value

ConnectionState

ConnectionState.Open, ConnectionState.Closed or ConnectionState.Connecting

Timezone

The connection's timezone as reported by PostgreSQL, in the IANA/Olson database format.

[Browsable(false)]
public string Timezone { get; }

Property Value

string

TypeMapper

The connection-specific type mapper - all modifications affect this connection only, and are lost when it is closed.

public INpgsqlTypeMapper TypeMapper { get; }

Property Value

INpgsqlTypeMapper

UserCertificateValidationCallback

Verifies the remote Secure Sockets Layer (SSL) certificate used for authentication. Ignored if TrustServerCertificate is set.

public RemoteCertificateValidationCallback UserCertificateValidationCallback { get; set; }

Property Value

RemoteCertificateValidationCallback

Remarks

See https://msdn.microsoft.com/en-us/library/system.net.security.remotecertificatevalidationcallback(v=vs.110).aspx

UserName

User name.

public string UserName { get; }

Property Value

string

Methods

BeginBinaryExport(string)

Begins a binary COPY TO STDOUT operation, a high-performance data export mechanism from a PostgreSQL table.

public NpgsqlBinaryExporter BeginBinaryExport(string copyToCommand)

Parameters

copyToCommand string

A COPY TO STDOUT SQL command

Returns

NpgsqlBinaryExporter

A NpgsqlBinaryExporter which can be used to read rows and columns

Remarks

See http://www.postgresql.org/docs/current/static/sql-copy.html.

BeginBinaryImport(string)

Begins a binary COPY FROM STDIN operation, a high-performance data import mechanism to a PostgreSQL table.

public NpgsqlBinaryImporter BeginBinaryImport(string copyFromCommand)

Parameters

copyFromCommand string

A COPY FROM STDIN SQL command

Returns

NpgsqlBinaryImporter

A NpgsqlBinaryImporter which can be used to write rows and columns

Remarks

See http://www.postgresql.org/docs/current/static/sql-copy.html.

BeginDbTransaction(IsolationLevel)

Begins a database transaction with the specified isolation level.

protected override DbTransaction BeginDbTransaction(IsolationLevel isolationLevel)

Parameters

isolationLevel IsolationLevel

The isolation level under which the transaction should run.

Returns

DbTransaction

An DbTransaction object representing the new transaction.

Remarks

Currently the IsolationLevel ReadCommitted and Serializable are supported by the PostgreSQL backend. There's no support for nested transactions.

BeginRawBinaryCopy(string)

Begins a raw binary COPY operation (TO STDOUT or FROM STDIN), a high-performance data export/import mechanism to a PostgreSQL table. Note that unlike the other COPY API methods, BeginRawBinaryCopy(string) doesn't implement any encoding/decoding and is unsuitable for structured import/export operation. It is useful mainly for exporting a table as an opaque blob, for the purpose of importing it back later.

public NpgsqlRawCopyStream BeginRawBinaryCopy(string copyCommand)

Parameters

copyCommand string

A COPY TO STDOUT or COPY FROM STDIN SQL command

Returns

NpgsqlRawCopyStream

A NpgsqlRawCopyStream that can be used to read or write raw binary data.

Remarks

See http://www.postgresql.org/docs/current/static/sql-copy.html.

BeginTextExport(string)

Begins a textual COPY TO STDOUT operation, a data export mechanism from a PostgreSQL table. It is the user's responsibility to parse the textual input according to the format specified in copyToCommand.

public TextReader BeginTextExport(string copyToCommand)

Parameters

copyToCommand string

A COPY TO STDOUT SQL command

Returns

TextReader

A TextReader that can be used to read textual data.

Remarks

See http://www.postgresql.org/docs/current/static/sql-copy.html.

BeginTextImport(string)

Begins a textual COPY FROM STDIN operation, a data import mechanism to a PostgreSQL table. It is the user's responsibility to send the textual input according to the format specified in copyFromCommand.

public TextWriter BeginTextImport(string copyFromCommand)

Parameters

copyFromCommand string

A COPY FROM STDIN SQL command

Returns

TextWriter

A TextWriter that can be used to send textual data.

Remarks

See http://www.postgresql.org/docs/current/static/sql-copy.html.

BeginTransaction()

Begins a database transaction.

public NpgsqlTransaction BeginTransaction()

Returns

NpgsqlTransaction

A NpgsqlTransaction object representing the new transaction.

Remarks

Currently there's no support for nested transactions. Transactions created by this method will have Read Committed isolation level.

BeginTransaction(IsolationLevel)

Begins a database transaction with the specified isolation level.

public NpgsqlTransaction BeginTransaction(IsolationLevel level)

Parameters

level IsolationLevel

The isolation level under which the transaction should run.

Returns

NpgsqlTransaction

A NpgsqlTransaction object representing the new transaction.

Remarks

Currently the IsolationLevel ReadCommitted and Serializable are supported by the PostgreSQL backend. There's no support for nested transactions.

ChangeDatabase(string)

This method changes the current database by disconnecting from the actual database and connecting to the specified.

public override void ChangeDatabase(string dbName)

Parameters

dbName string

The name of the database to use in place of the current database.

ClearAllPools()

Clear all connection pools.

public static void ClearAllPools()

ClearPool(NpgsqlConnection)

Clear connection pool.

public static void ClearPool(NpgsqlConnection connection)

Parameters

connection NpgsqlConnection

CloneWith(string)

Clones this connection, replacing its connection string with the given one. This allows creating a new connection with the same security information (password, SSL callbacks) while changing other connection parameters (e.g. database or pooling)

public NpgsqlConnection CloneWith(string connectionString)

Parameters

connectionString string

Returns

NpgsqlConnection

Close()

releases the connection to the database. If the connection is pooled, it will be made available for re-use. If it is non-pooled, the actual connection will be shutdown.

public override void Close()

CreateCommand()

Creates and returns a NpgsqlCommand object associated with the NpgsqlConnection.

public NpgsqlCommand CreateCommand()

Returns

NpgsqlCommand

A NpgsqlCommand object.

CreateDbCommand()

Creates and returns a DbCommand object associated with the IDbConnection.

protected override DbCommand CreateDbCommand()

Returns

DbCommand

A DbCommand object.

Dispose(bool)

Releases all resources used by the NpgsqlConnection.

protected override void Dispose(bool disposing)

Parameters

disposing bool

true when called from Dispose(); false when being called from the finalizer.

EnlistTransaction(Transaction)

Enlist transation.

public override void EnlistTransaction(Transaction transaction)

Parameters

transaction Transaction

GetSchema()

Returns the supported collections

public override DataTable GetSchema()

Returns

DataTable

GetSchema(string)

Returns the schema collection specified by the collection name.

public override DataTable GetSchema(string collectionName)

Parameters

collectionName string

The collection name.

Returns

DataTable

The collection specified.

GetSchema(string, string[])

Returns the schema collection specified by the collection name filtered by the restrictions.

public override DataTable GetSchema(string collectionName, string[] restrictions)

Parameters

collectionName string

The collection name.

restrictions string[]

The restriction values to filter the results. A description of the restrictions is contained in the Restrictions collection.

Returns

DataTable

The collection specified.

MapCompositeGlobally<T>(string, INpgsqlNameTranslator)

Maps a CLR type to a PostgreSQL composite type for use with all connections created from now on. Existing connections aren't affected.

[Obsolete("Use NpgsqlConnection.GlobalTypeMapper.MapComposite() instead")]
public static void MapCompositeGlobally<T>(string pgName = null, INpgsqlNameTranslator nameTranslator = null) where T : new()

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

T

The .NET type to be mapped

Remarks

CLR fields and properties by string to PostgreSQL enum labels. The translation strategy can be controlled by the nameTranslator parameter, which defaults to NpgsqlSnakeCaseNameTranslator. You can also use the PgNameAttribute on your members to manually specify a PostgreSQL enum label. If there is a discrepancy between the .NET and database labels while a composite is read or written, an exception will be raised.

To map the type for a specific connection, use the MapEnum<TEnum>(string, INpgsqlNameTranslator) method.

MapComposite<T>(string, INpgsqlNameTranslator)

Maps a CLR type to a PostgreSQL composite type for use with this connection.

[Obsolete("Use NpgsqlConnection.TypeMapper.MapComposite() instead")]
public void MapComposite<T>(string pgName = null, INpgsqlNameTranslator nameTranslator = null) where T : new()

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

T

The .NET type to be mapped

Remarks

CLR fields and properties by string to PostgreSQL enum labels. The translation strategy can be controlled by the nameTranslator parameter, which defaults to NpgsqlSnakeCaseNameTranslator. You can also use the PgNameAttribute on your members to manually specify a PostgreSQL enum label. If there is a discrepancy between the .NET and database labels while a composite is read or written, an exception will be raised.

Can only be invoked on an open connection; if the connection is closed the mapping is lost.

To avoid mapping the type for each connection, use the MapCompositeGlobally<T>(string, INpgsqlNameTranslator) method.

MapEnumGlobally<TEnum>(string, INpgsqlNameTranslator)

Maps a CLR enum to a PostgreSQL enum type for use with all connections created from now on. Existing connections aren't affected.

[Obsolete("Use NpgsqlConnection.GlobalTypeMapper.MapEnum() instead")]
public static void MapEnumGlobally<TEnum>(string pgName = null, INpgsqlNameTranslator nameTranslator = null) where TEnum : struct

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

TEnum

The .NET enum type to be mapped

Remarks

CLR enum labels are mapped by name to PostgreSQL enum labels. The translation strategy can be controlled by the nameTranslator parameter, which defaults to NpgsqlSnakeCaseNameTranslator. You can also use the PgNameAttribute on your enum fields to manually specify a PostgreSQL enum label. If there is a discrepancy between the .NET and database labels while an enum is read or written, an exception will be raised.

To map the type for a specific connection, use the MapEnum<TEnum>(string, INpgsqlNameTranslator) method.

MapEnum<TEnum>(string, INpgsqlNameTranslator)

Maps a CLR enum to a PostgreSQL enum type for use with this connection.

[Obsolete("Use NpgsqlConnection.TypeMapper.MapEnum() instead")]
public void MapEnum<TEnum>(string pgName = null, INpgsqlNameTranslator nameTranslator = null) where TEnum : struct

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

TEnum

The .NET enum type to be mapped

Remarks

CLR enum labels are mapped by name to PostgreSQL enum labels. The translation strategy can be controlled by the nameTranslator parameter, which defaults to NpgsqlSnakeCaseNameTranslator. You can also use the PgNameAttribute on your enum fields to manually specify a PostgreSQL enum label. If there is a discrepancy between the .NET and database labels while an enum is read or written, an exception will be raised.

Can only be invoked on an open connection; if the connection is closed the mapping is lost.

To avoid mapping the type for each connection, use the MapEnumGlobally<TEnum>(string, INpgsqlNameTranslator) method.

Open()

Opens a database connection with the property settings specified by the ConnectionString.

public override void Open()

OpenAsync(CancellationToken)

This is the asynchronous version of Open().

public override Task OpenAsync(CancellationToken cancellationToken)

Parameters

cancellationToken CancellationToken

The cancellation instruction.

Returns

Task

A task representing the asynchronous operation.

Remarks

Do not invoke other methods and properties of the NpgsqlConnection object until the returned Task is complete.

ReloadTypes()

Flushes the type cache for this connection's connection string and reloads the types for this connection only. Type changes will appear for other connections only after they are re-opened from the pool.

public void ReloadTypes()

UnmapCompositeGlobally<T>(string, INpgsqlNameTranslator)

Removes a previous global enum mapping.

[Obsolete("Use NpgsqlConnection.GlobalTypeMapper.UnmapComposite() instead")]
public static void UnmapCompositeGlobally<T>(string pgName, INpgsqlNameTranslator nameTranslator = null) where T : new()

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

T

UnmapEnumGlobally<TEnum>(string, INpgsqlNameTranslator)

Removes a previous global enum mapping.

[Obsolete("Use NpgsqlConnection.GlobalTypeMapper.UnmapEnum() instead")]
public static void UnmapEnumGlobally<TEnum>(string pgName = null, INpgsqlNameTranslator nameTranslator = null) where TEnum : struct

Parameters

pgName string

A PostgreSQL type name for the corresponding enum type in the database. If null, the name translator given in nameTranslatorwill be used.

nameTranslator INpgsqlNameTranslator

A component which will be used to translate CLR names (e.g. SomeClass) into database names (e.g. some_class). Defaults to NpgsqlSnakeCaseNameTranslator

Type Parameters

TEnum

UnprepareAll()

Unprepares all prepared statements on this connection.

public void UnprepareAll()

Wait()

Waits until an asynchronous PostgreSQL messages (e.g. a notification) arrives, and exits immediately. The asynchronous message is delivered via the normal events (Notification, Notice).

public void Wait()

Wait(int)

Waits until an asynchronous PostgreSQL messages (e.g. a notification) arrives, and exits immediately. The asynchronous message is delivered via the normal events (Notification, Notice).

public bool Wait(int timeout)

Parameters

timeout int

The time-out value, in milliseconds, passed to ReceiveTimeout. The default value is 0, which indicates an infinite time-out period. Specifying -1 also indicates an infinite time-out period.

Returns

bool

true if an asynchronous message was received, false if timed out.

Wait(TimeSpan)

Waits until an asynchronous PostgreSQL messages (e.g. a notification) arrives, and exits immediately. The asynchronous message is delivered via the normal events (Notification, Notice).

public bool Wait(TimeSpan timeout)

Parameters

timeout TimeSpan

The time-out value is passed to ReceiveTimeout.

Returns

bool

true if an asynchronous message was received, false if timed out.

WaitAsync()

Waits asynchronously until an asynchronous PostgreSQL messages (e.g. a notification) arrives, and exits immediately. The asynchronous message is delivered via the normal events (Notification, Notice).

public Task WaitAsync()

Returns

Task

WaitAsync(CancellationToken)

Waits asynchronously until an asynchronous PostgreSQL messages (e.g. a notification) arrives, and exits immediately. The asynchronous message is delivered via the normal events (Notification, Notice). CancelationToken can not cancel wait operation if underlying NetworkStream does not support it (see https://stackoverflow.com/questions/12421989/networkstream-readasync-with-a-cancellation-token-never-cancels ).

public Task WaitAsync(CancellationToken cancellationToken)

Parameters

cancellationToken CancellationToken

Returns

Task

Events

Notice

Fires when PostgreSQL notices are received from PostgreSQL.

public event NoticeEventHandler Notice

Event Type

NoticeEventHandler

Remarks

PostgreSQL notices are non-critical messages generated by PostgreSQL, either as a result of a user query (e.g. as a warning or informational notice), or due to outside activity (e.g. if the database administrator initiates a "fast" database shutdown).

Note that notices are very different from notifications (see the Notification event).

Notification

Fires when PostgreSQL notifications are received from PostgreSQL.

public event NotificationEventHandler Notification

Event Type

NotificationEventHandler

Remarks

PostgreSQL notifications are sent when your connection has registered for notifications on a specific channel via the LISTEN command. NOTIFY can be used to generate such notifications, allowing for an inter-connection communication channel.

Note that notifications are very different from notices (see the Notice event).