Data structures for smart large objects
Because a smart large object can be huge, HCL Informix® has two alternatives to store the content of a smart large object.
Therefore, instead of storing the content of a smart large object
in a database table, HCL Informix does
the following:
- Stores the content of the smart large object in an sbspace
- Stores a pointer to the smart large object in the database table
Because a smart large object can be huge, the HCL Informix
ODBC Driver application cannot receive a smart large
object in a variable. Instead, the application sends or receives information about the smart large
object in a data structure. The following table describes the data structures that HCL Informix
ODBC Driver uses for smart large objects.
| Data structure | Name | Description |
|---|---|---|
| lofd | Smart-large-object file descriptor | Provides access to a smart large object. Uses a file descriptor to access smart-large-object data as if it were in an operating-system file. |
| loptr | Smart-large-object pointer structure | Provides security information and a pointer to a smart large object. This structure is the data that the database server stores in a database table for a smart large object. Therefore, SQL statements such as INSERT and SELECT accept a smart-large-object pointer structure as a value for a column or a parameter that has a data type of smart large object. |
| lospec | Smart-large-object specification structure | Specifies the storage characteristics for a smart large object. |
| lostat | Smart-large-object status structure | Stores status information for a smart large object. Normally you can fetch a user-defined data type (UDT) in either binary or character representation. However, it is not possible to convert a smart-large-object status structure to character representation. Therefore, you need to use SQL_C_BINARY as the HCL Informix ODBC Driver C data type for lostat. |
Restriction: These data structures are opaque to HCL Informix
ODBC Driver applications and their internal structures
might change. Therefore, do not access the internal structures directly. Use the smart-large-object
client functions to manipulate the data structures.
The application is responsible for allocating space for these smart-large-object data structures.