Multiple Piece Write Operation

This mechanism is used when the size of the buffer available is smaller than the total amount of data to be written. The total amount of data to be written is set by using the PollingAmount (OraLOB/BFILE) property.

The Offset (OraLOB/BFILE) property is used only once to set the offset for the first piece write operation. After the first time, it is automatically increased by the size of the previous piece. The Status (OraLOB/BFILE) property must be checked for success of each piece write operation. If Status property returns ORALOB_NEED_DATA, the Write method must be called again. This must continue until the amount specified by PollingAmount property has been sent. The piecetype argument of Write method must be set to ORALOB_FIRST_PIECE for the first piece that is sent and last piece Write operation ends with setting piecetype argument to ORALOB_LAST_PIECE. At the end of multiple piece operation, the Status property returns ORALOB_NO_DATA.

The following example writes 102k of data in 10k chunks to the part_image column from the local file 'partimage.dat' at offset of 1000.

Dim buffer() as byte

chunksize = 10000

ReDim buffer(chunksize)

Set OO4OSession = CreateObject("OracleInProcServer.XOraSession")

Set InvDb = OO4OSession.OpenDatabase("INVDB", "scott/tiger", 0)

Set Part = InvDb.CreateDynaset("select * from part", 0&)

Set PartImage = Part.Fields("part_image").Value

FNum = FreeFile

Open "PartImage.Dat" For Binary As #FNum

PartImage.Offset = 1000

PartImage.PollingAmount =102000

remainder = 102000

Part.Edit

Get #FNum, , buffer

amount_written = PartImage.Write(buffer, chunksize,

ORALOB_FIRST_PIECE)

While PartImage.Status = ORALOB_NEED_DATA

remainder = remainder - chunksize

If remainder < chunksize Then

piecetype = ORALOB_LAST_PIECE

chunksize = remainder

Else

piecetype = ORALOB_NEXT_PIECE

End If

Get #FNum, , buffer

amount_written = PartImage.Write(buffer, chunksize, piecetype)

Wend

Close FNum

Part.Update