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Client APIs and toolsYou can use the HCL Informix® implementation of client APIs to develop applications for Informix® database servers.
ESQL/C GuideThe Informix® ESQL/C Programmer's Manual explains how to use Informix® ESQL/C, the Informix® implementation of Embedded Structured Query Language (SQL) for C (ESQL/C), to create client applications with database-management capabilities.
What is Informix® ESQL/C?
Smart large objectsA smart large object is a data type that stores large, non-relational data objects such as images, sound clips, documents, graphics, maps and other large objects, and allows you to perform read, write, and seek operations on those objects.
Accessing a smart large object
Open a smart large objectWhen you open a smart large object, you obtain an LO file descriptor for the smart large object. Through the LO file descriptor, you can access the data of a smart large object as if it were in an operating-system file.
Access modesWhen you open a smart large object, you specify the access mode for the data.
The LO_APPEND flag

The LO_APPEND flag

When you open a smart large object with LO_APPEND only, the smart large object is opened as read-only. Seek operations move the file pointer but write operations to the smart large object fail and the file pointer is not moved from its position just before the write. Read operations occur from where the file pointer is positioned and then the file pointer is moved.

You can mask the LO_APPEND flag with another access mode. In any of these OR combinations, the seek operation remains unaffected. The following table shows the effect on the read and write operations that each of the OR combinations has.


OR operation	Read operations	Write operations
LO_RDONLY \| LO_APPEND	Occur at the file position and then move the file position to the end of the data that was read	Fail and do not move the file position.
LO_WRONLY \| LO_APPEND	Fail and do not move the file position	Move the file position to the end of the smart large object and then write the data; file position is at the end of the data after the write.
LO_RDWR \| LO_APPEND	Occur at the file position and then move the file position to the end of the data that was read	Move the file position to the end of the smart large object and then write the data; file position is at the end of the data after the write.

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