Represents a large object binary (LOB) data type stored on an Oracle server. This class cannot be inherited.
Assembly: System.Data.OracleClient (in System.Data.OracleClient.dll)
Thetype exposes the following members.
|CanRead||Gets a value indicating whether the LOB stream can be read. (Overrides Stream::CanRead.)|
|CanSeek||Gets a value indicating whether forward and backward seek operations can be performed. (Overrides Stream::CanSeek.)|
|CanTimeout||Gets a value that determines whether the current stream can time out. (Inherited from Stream.)|
|CanWrite||Always returns true, regardless of whether the LOB supports writing or not. (Overrides Stream::CanWrite.)|
|ChunkSize||Gets a value indicating the minimum number of bytes to retrieve from or send to the server during a read/write operation.|
|Connection||Gets the OracleConnection used by this instance of the .|
|IsBatched||Gets a value indicating whether an application called the BeginBatch method.|
|IsNull||Gets a value that indicates whether the is a Null stream.|
|IsTemporary||Gets a value indicating whether the is a temporary LOB.|
|Length||Gets a value that returns the size of the . (Overrides Stream::Length.)|
|LobType||Gets a value that returns the LOB data type.|
|Position||Gets the current read position in the stream. (Overrides Stream::Position.)|
|ReadTimeout||Gets or sets a value, in miliseconds, that determines how long the stream will attempt to read before timing out. (Inherited from Stream.)|
|Value||Gets the common language runtime stream value equivalent of the underlying value.|
|WriteTimeout||Gets or sets a value, in miliseconds, that determines how long the stream will attempt to write before timing out. (Inherited from Stream.)|
|Append||Appends data from the specified LOB to the current LOB.|
|BeginBatch()||Prevents server-side triggers from firing while performing multiple read operations.|
|BeginBatch(OracleLobOpenMode)||Prevents server-side triggers from firing while performing multiple read and write operations in the specified access mode.|
|BeginRead||Begins an asynchronous read operation. (Inherited from Stream.)|
|BeginWrite||Begins an asynchronous write operation. (Inherited from Stream.)|
|Clone||Creates a new object that references the same Oracle LOB as the original object.|
|Close||Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. (Inherited from Stream.)|
|CopyTo(OracleLob)||Copies from this to a destination .|
|CopyTo(Stream)||Reads the bytes from the current stream and writes them to the destination stream. (Inherited from Stream.)|
|CopyTo(OracleLob, Int64)||Copies from this to a destination with the specified amount of data.|
|CopyTo(Stream, Int32)||Reads all the bytes from the current stream and writes them to a destination stream, using a specified buffer size. (Inherited from Stream.)|
|CopyTo(Int64, OracleLob, Int64, Int64)||Copies from this to a destination with the specified amount of data, and the source offset.|
|CreateObjRef||Creates an object that contains all the relevant information required to generate a proxy used to communicate with a remote object. (Inherited from MarshalByRefObject.)|
|CreateWaitHandle||Obsolete. Allocates a WaitHandle object. (Inherited from Stream.)|
|Dispose()||Releases all resources used by the Stream. (Inherited from Stream.)|
|Dispose(Boolean)||Releases the unmanaged resources used by the Stream and optionally releases the managed resources. (Inherited from Stream.)|
|EndBatch||Allows server-side triggers to resume firing after performing multiple write operations.|
|EndRead||Waits for the pending asynchronous read to complete. (Inherited from Stream.)|
|EndWrite||Ends an asynchronous write operation. (Inherited from Stream.)|
|Equals(Object)||Determines whether the specified Object is equal to the current Object. (Inherited from Object.)|
|Erase()||Erases all data from this .|
|Erase(Int64, Int64)||Erases the specified amount of data from this .|
|Finalize||Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)|
|Flush||Not currently supported. (Overrides Stream::Flush().)|
|GetHashCode||Serves as a hash function for a particular type. (Inherited from Object.)|
|GetLifetimeService||Retrieves the current lifetime service object that controls the lifetime policy for this instance. (Inherited from MarshalByRefObject.)|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|InitializeLifetimeService||Obtains a lifetime service object to control the lifetime policy for this instance. (Inherited from MarshalByRefObject.)|
|MemberwiseClone()||Creates a shallow copy of the current Object. (Inherited from Object.)|
|MemberwiseClone(Boolean)||Creates a shallow copy of the current MarshalByRefObject object. (Inherited from MarshalByRefObject.)|
|ObjectInvariant||Infrastructure. Provides support for a Contract. (Inherited from Stream.)|
|Read||Reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. (Overrides Stream::Read(array<Byte>, Int32, Int32).)|
|ReadByte||Reads a byte from the stream and advances the position within the stream by one byte, or returns -1 if at the end of the stream. (Inherited from Stream.)|
|Seek||Sets the position on the current stream. (Overrides Stream::Seek(Int64, SeekOrigin).)|
|SetLength||Sets the length of the stream to a value less than the current length. (Overrides Stream::SetLength(Int64).)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
|Write||Writes a sequence of bytes to the current stream, and advances the current position within this stream by the number of bytes written. (Overrides Stream::Write(array<Byte>, Int32, Int32).)|
|WriteByte||Writes a byte to the current position in the stream, and advances the position within the stream by one byte. (Overrides Stream::WriteByte(Byte).)|
An differs from an OracleBFile in that the data is stored on the server instead of in a physical file in the operating system. It can also be a read-write object, unlike an OracleBFile, which is always read-only.
An may be one of these OracleType data types.
OracleType data type
An Oracle CLOB data type that contains character data, based on the default character set on the server, with a maximum size of 4 GB. This maps to String.
An Oracle NCLOB data type that contains character data, based on the national character set on the server with a maximum size of 4 GB. This maps to String.
A .NET application developer can retrieve the Oracle LOB values into basic .NET data types, such as Array of type Byte and String, or the specialized data type. The class supports reading data from and writing to the Oracle LOB in the Oracle database.
The following are the main characteristics of an data type that distinguish it from basic .NET data types:
After you retrieve the Oracle LOB value from the Oracle database into the class, you can change the LOB data in an open transaction and your changes are directly reflected to the database. If you retrieve the Oracle LOB value into an Array of type Byte or String and update these arrays, your changes are not reflected to the database.
When you use the class to access a chunk of a LOB value, only that chunk is passed from the Oracle database to the client. When you use the GetChars method to access a chunk of a LOB value, the entire contents of the value are passed from the Oracle database to the client.
To obtain an object, call the GetOracleLob method.
You can construct an that is NULL using this format:
OracleLob myLob = OracleLob.Null;
This technique is used primarily to test whether a LOB returned from the server is NULL, as this example illustrates:
If(myLob == OracleLob.Null)
A NULL LOB behaves similarly to a zero-byte LOB in that Read succeeds and always returns zero bytes.
Selecting a LOB column that contains a null value returns Null.
You must begin a transaction before obtaining a temporary LOB. Otherwise, the OracleDataReader may fail to obtain data later.
You can also open a temporary LOB in Oracle by calling the DBMS_LOB.CREATETEMPORARY system stored procedure and binding a LOB output parameter. On the client side, a temporary LOB behaves like a table-based LOB. For example, to update the temporary LOB, it must be enclosed in a transaction.
The following C# example demonstrates how to open a temporary LOB.
OracleConnection connection = new OracleConnection("server=MyServer; integrated security=yes;"); connection.Open(); OracleTransaction transaction = connection.BeginTransaction(); OracleCommand command = connection.CreateCommand(); command.Transaction = transaction; command.CommandText = "declare xx blob; begin dbms_lob.createtemporary(xx, false, 0); :tempblob := xx; end;"; command.Parameters.Add(new OracleParameter("tempblob", OracleType.Blob)).Direction = ParameterDirection.Output; command.ExecuteNonQuery(); OracleLob tempLob = (OracleLob)command.Parameters.Value; byte tempbuff = new byte; tempLob.BeginBatch(OracleLobOpenMode.ReadWrite); tempLob.Write(tempbuff,0,tempbuff.Length); tempLob.EndBatch(); command.Parameters.Clear(); command.CommandText = "MyTable.MyProc"; command.CommandType = CommandType.StoredProcedure; command.Parameters.Add(new OracleParameter("ImportDoc", OracleType.Blob)).Value = tempLob; command.ExecuteNonQuery(); transaction.Commit(); connection.Close
Temporary LOBs are only closed when the connection is closed, but with pooling and under load, temporary LOBs do not close. This can be resolved by disposing the temporary LOB, by invoking tempLob.Dispose().
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.