You can unload LOB data in one of two ways.
About this task
LOB columns can be unloaded with either of the following
methods:
- The
LOB column can be unloaded to the output records. The LOB column
value can be placed in the OUTPUT record with or without any other
unloading column values. The output record can be in delimited or
non-delimited format. For a non-delimited format, the LOB column is
handled like a variable character with a 2-byte length preceding the
LOB value. For a delimited format there are no length bytes present.
If the total output record length is more than 32 KB, unload the record
in spanned record format by specifying the SPANNED YES option.
- The LOB column can be unloaded to a separate file whether the
LOB column length is less than 32K or not.
Procedure
To unload LOB data, use one of the following methods:
- To unload LOB data directly to output record:
Specify
LOB as the output field type. If the output is a non-delimited format,
a 2-byte length will precede the value of the LOB. For delimited output,
no length field is present. LOB is the only acceptable field type
when unloading the LOB data directly to the output record. No data
type conversion applies and you cannot specify FROMCOPY.
- To unload LOB data to a separate file:
- Create an UNLOAD utility control statement. Specify BLOBF, CLOBF
or DBCLOBF to indicate that the output column contains a filename
which the LOB value is to be unloaded. You cannot specify FROMCOPY.
- Use the template control statement to create the LOB output file
and filename. If data sets are not created and the DSN type is not
specified on the template, UNLOAD will use PDS as the data set type.
PDS has a limit of single volume. The output file uses multiple volumes,
so you must specify HFS as the DSN type. See Data sets that UNLOAD uses.
If
you unload data to a separate file, and the LOB column from which
you unload is empty, the data set that is specified by UNLDDN contains
one of the following items:
- A blank file name if the source column is specified as CHAR CLOBF,
CHAR BLOBF, or CHAR DBCLOBF
- A file name with length 0 if the source column is specified as
VARCHAR CLOBF, VARCHAR BLOBF, or VARCHAR DBCLOBF
The UNLOAD utility does not create a data set or file for the
empty LOB.