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Inheritance Hierarchy

Dynamic Server uses an inheritance hierarchy to obtain storage characteristics. Figure 6 shows the inheritance hierarchy for smart-large-object storage characteristics.

Figure 6. Inheritance Hierarchy for Storage Characteristics
This graphic illustrates the inheritance hierarchy for smart-large-object storage characteristics. The graphic contains four horizontal boxes arranged in a vertical line and connected by three down-facing arrows. The boxes are labeled as such: Database server storage characteristics (system defaults and the ONCONFIG file), sbspace storage characteristics (assigned when the database server creates the sbspace), Column-level storage characteristics (assigned with the CREATE TABLE statement), and User-defined storage characteristics (assigned from within an IBM Informix ODBC application.)

System-Specified Storage Characteristics

Dynamic Server uses one of the following sets of storage characteristics as the system-specified storage characteristics:

Warning:
An error will occur if the sbspacename configuration parameter is not specified and the smart-large-object specification structure does not contain the name of the target sbspace.

It is recommended that you use the system-specified storage characteristics for the disk-storage information. For more information about sbspaces and the description of the onspaces utility, see your IBM Informix: Administrator's Guide.

To use system-specified storage characteristics for a new smart large object
  1. Call ifx_lo_def_create_spec() to allocate a smart-large-object specification structure and to initialize the structure to null values.
  2. Call ifx_lo_create() to create an instance of the smart large object.

Column-Level Storage Characteristics

The CREATE TABLE statement assigns storage characteristics to a database column. The PUT clause of the CREATE TABLE statement specifies storage characteristics for a smart-large-object column. The syscolattribs system catalog table stores the column-level storage characteristics.

To use column-level storage characteristics for a new smart-large-object instance
  1. Call ifx_lo_def_create_spec() to allocate a smart-large-object specification structure and initialize this structure to null values.
  2. Call ifx_lo_col_info() to retrieve the column-level storage characteristics and store them in the specified smart-large-object specification structure.
  3. Call ifx_lo_create() to create an instance of the smart large object.

User-Defined Storage Characteristics

You can define a unique set of storage characteristics for a new smart large object, as follows:

To specify user-defined storage characteristics, call an ifx_lo_specset_* function.

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