Class NpgsqlLargeObjectManager

Namespace

Npgsql

Assembly

Npgsql.dll

Large object manager. This class can be used to store very large files in a PostgreSQL database.

[Obsolete("NpgsqlLargeObjectManager allows manipulating PostgreSQL large objects via publicly available PostgreSQL functions (lo_read, lo_write); call these yourself directly.")]
public class NpgsqlLargeObjectManager

Inheritance

object

NpgsqlLargeObjectManager

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Constructors

NpgsqlLargeObjectManager(NpgsqlConnection)

Creates an NpgsqlLargeObjectManager for this connection. The connection must be opened to perform remote operations.

public NpgsqlLargeObjectManager(NpgsqlConnection connection)

Parameters

connection NpgsqlConnection

Properties

Has64BitSupport

Since PostgreSQL 9.3, large objects larger than 2GB can be handled, up to 4TB. This property returns true whether the PostgreSQL version is >= 9.3.

public bool Has64BitSupport { get; }

Property Value

bool

MaxTransferBlockSize

The largest chunk size (in bytes) read and write operations will read/write each roundtrip to the network. Default 4 MB.

public int MaxTransferBlockSize { get; set; }

Property Value

int

Methods

Create(uint)

Create an empty large object in the database. If an oid is specified but is already in use, an PostgresException will be thrown.

public uint Create(uint preferredOid = 0)

Parameters

preferredOid uint

A preferred oid, or specify 0 if one should be automatically assigned

Returns

uint

The oid for the large object created

Exceptions

PostgresException

If an oid is already in use

CreateAsync(uint, CancellationToken)

Create an empty large object in the database. If an oid is specified but is already in use, an PostgresException will be thrown.

public Task<uint> CreateAsync(uint preferredOid, CancellationToken cancellationToken = default)

Parameters

preferredOid uint

A preferred oid, or specify 0 if one should be automatically assigned

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task<uint>

The oid for the large object created

Exceptions

PostgresException

If an oid is already in use

ExportRemote(uint, string)

Exports a large object stored in the database to a file on the backend. This requires superuser permissions.

public void ExportRemote(uint oid, string path)

Parameters

oid uint

Oid of the object to export

path string

Path to write the file on the backend

ExportRemoteAsync(uint, string, CancellationToken)

Exports a large object stored in the database to a file on the backend. This requires superuser permissions.

public Task ExportRemoteAsync(uint oid, string path, CancellationToken cancellationToken = default)

Parameters

oid uint

Oid of the object to export

path string

Path to write the file on the backend

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task

ImportRemote(string, uint)

Imports a large object to be stored as a large object in the database from a file stored on the backend. This requires superuser permissions.

public void ImportRemote(string path, uint oid = 0)

Parameters

path string

Path to read the file on the backend

oid uint

A preferred oid, or specify 0 if one should be automatically assigned

ImportRemoteAsync(string, uint, CancellationToken)

Imports a large object to be stored as a large object in the database from a file stored on the backend. This requires superuser permissions.

public Task ImportRemoteAsync(string path, uint oid, CancellationToken cancellationToken = default)

Parameters

path string

Path to read the file on the backend

oid uint

A preferred oid, or specify 0 if one should be automatically assigned

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task

OpenRead(uint)

Opens a large object on the backend, returning a stream controlling this remote object. A transaction snapshot is taken by the backend when the object is opened with only read permissions. When reading from this object, the contents reflects the time when the snapshot was taken. Note that this method, as well as operations on the stream must be wrapped inside a transaction.

public NpgsqlLargeObjectStream OpenRead(uint oid)

Parameters

oid uint

Oid of the object

Returns

NpgsqlLargeObjectStream

An NpgsqlLargeObjectStream

OpenReadAsync(uint, CancellationToken)

Opens a large object on the backend, returning a stream controlling this remote object. A transaction snapshot is taken by the backend when the object is opened with only read permissions. When reading from this object, the contents reflects the time when the snapshot was taken. Note that this method, as well as operations on the stream must be wrapped inside a transaction.

public Task<NpgsqlLargeObjectStream> OpenReadAsync(uint oid, CancellationToken cancellationToken = default)

Parameters

oid uint

Oid of the object

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task<NpgsqlLargeObjectStream>

An NpgsqlLargeObjectStream

OpenReadWrite(uint)

Opens a large object on the backend, returning a stream controlling this remote object. Note that this method, as well as operations on the stream must be wrapped inside a transaction.

public NpgsqlLargeObjectStream OpenReadWrite(uint oid)

Parameters

oid uint

Oid of the object

Returns

NpgsqlLargeObjectStream

An NpgsqlLargeObjectStream

OpenReadWriteAsync(uint, CancellationToken)

Opens a large object on the backend, returning a stream controlling this remote object. Note that this method, as well as operations on the stream must be wrapped inside a transaction.

public Task<NpgsqlLargeObjectStream> OpenReadWriteAsync(uint oid, CancellationToken cancellationToken = default)

Parameters

oid uint

Oid of the object

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task<NpgsqlLargeObjectStream>

An NpgsqlLargeObjectStream

Unlink(uint)

Deletes a large object on the backend.

public void Unlink(uint oid)

Parameters

oid uint

Oid of the object to delete

UnlinkAsync(uint, CancellationToken)

Deletes a large object on the backend.

public Task UnlinkAsync(uint oid, CancellationToken cancellationToken = default)

Parameters

oid uint

Oid of the object to delete

cancellationToken CancellationToken

An optional token to cancel the asynchronous operation. The default value is None.

Returns

Task