The fields of the locator structure

The locator structure has the following parts:
  • The loc_loctype field identifies the location of the simple-large-object data. It also indicates the variant type of the lc_union structure.

    For more information about loc_loctype, see Locations for simple-large-object data.

  • The lc_union structure is a union (overlapping variant structures) structure.

    The variant in use depends on where Informix ESQL/C can expect to find the simple large object at run time. For more information about this structure, see Locate simple large objects in memory and Locate simple large objects in files.

  • Several fields are common to all types of simple-large-object variables.
The lists the fields in the locator structure common to all simple-large-object locations.
Table 1. Fields in locator structure common to all simple-large-object data locations
Field Data type Description
loc_indicator 4-byte integer A value of -1 in the loc_indicator field indicates a null simple-large-object value. The Informix ESQL/C program can set the field to indicate insertion of a null value; Informix ESQL/C libraries set it on a select or fetch.

For consistent behavior on various platforms, it is advised to set the value of the indicator to 0 or -1. If indicator is not set you can experience inconsistent behavior. The value set in the indicator field takes the higher precedence when set.

You can also use the loc_indicator field to indicate an error when your program selects into memory. If the simple large object to be retrieved does not fit in the space provided, the loc_indicator field contains the actual size of the simple large object.
loc_size 4-byte integer Contains the size of the simple-large-object data in bytes. This field indicates the amount of simple-large-object data that the Informix ESQL/C libraries read or write. The Informix ESQL/C program sets loc_size when it inserts a simple large object in the database; the Informix ESQL/C libraries set loc_size after it selects or fetches a simple large object.
loc_status mint Indicates the status of the last locator operation. The Informix ESQL/C libraries set loc_status to zero when a locator operation is successful and to a negative value when an error occurs. The SQLCODE variable also contains this status value.
loc_type 4-byte integer Specifies whether the data type of the variable is TEXT (SQLTEXT) or BYTE (SQLBYTES). The sqltypes.h header file defines SQLTEXT and SQLBYTES.