DataBlade API Programmer's Manual

DataBlade API Programmer's Manual
Chapter 12: DataBlade API Function Descriptions

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mi_lo_writewithseek()

The mi_lo_writewithseek() function performs a seek operation and then writes a specified number of bytes of data to an open smart large object.

Syntax

#include "milo.h"

...
mi_integer mi_lo_writewithseek(conn, LO_fd, buf, nbytes, offset, whence)

		MI_CONNECTION *conn;

		MI_LO_FD LO_fd;

		const char *buf;

		mi_integer nbytes;

		mi_int8 *offset;

		mi_integer whence; 


conn
is a pointer to the connection descriptor that a previous call to mi_open() or mi_server_connect() established.

LO_fd
is an LO file descriptor for the smart large object to which to write.

buf
is a pointer to a user-allocated character buffer of at least nbytes bytes that contains the data to be written to the smart large object.

nbytes
is the number of bytes to write to the smart large object. This value cannot exceed 2 gigabytes.

offset
is a pointer to the 8-byte integer (mi_int8) offset from the starting LO seek position.

whence
is an integer value that identifies the starting LO seek position.







 



Valid in Client Application?

Valid in Server Routine?

Yes
Yes

Usage

The mi_lo_writewithseek() function writes nbytes of data to the smart large object that the LO_fd file descriptor identifies. The function obtains the data to write from the user-allocated buffer that buf references. The buffer must be less than 2 gigabytes in size.

The write begins at the LO seek position of LO_fd that the offset and whence arguments indicate, as follows:

The whence argument identifies the position from which to start the seek operation.


Whence Constant	Starting LO Seek Position
`MI_LO_SEEK_SET`	The start of the smart large object
`MI_LO_SEEK_CUR`	The current `LO` seek position in the smart large object
`MI_LO_SEEK_END`	The end of the smart large object

The offset argument identifies the offset, in bytes, relative to the starting seek position (which the whence argument specifies) at which to begin the write operation.

offset

whence

Tip: The mi_lo_writewithseek() function is useful in DataBlade client applications because it reduces the number of round trips between the client application and the database server.

If the database server writes less than nbytes of data to the smart large object, the mi_lo_writewithseek() function returns the number of bytes that it wrote and raises an exception. This condition can occur when the sbspace runs out of space.

Tip: The mi_lo_writewithseek() function replaces the mi_large_object_writewithseek() function, which Informix supports for backward compatibility only. Use mi_lo_writewithseek() for all new DataBlade routines.

Return Values

>=0
The number of bytes that the function wrote from the buf character buffer to open the smart large object.

MI_ERROR
The function was not successful.

DataBlade API Programmer's ManualChapter 12: DataBlade API Function Descriptions Home Contents Index Master Index New Book

mi_lo_writewithseek()

Syntax

Usage

Return Values >=0 The number of bytes that the function wrote from the buf character buffer to open the smart large object. MI_ERROR The function was not successful.

Related Topics

DataBlade API Programmer's Manual
Chapter 12: DataBlade API Function Descriptions

Home Contents Index Master Index New Book

Return Values

>=0
The number of bytes that the function wrote from the buf character buffer to open the smart large object.

MI_ERROR
The function was not successful.