When unloading a database from an image copy, why is the RECOVER function invoked?

Products

• Database Organizer for IMS for z/OS
• Database Organizer (IMS Tools)
• DATABASE MANAGEMENT SOLUTIONS FOR IMS FOR Z/OS

Issue/Introduction

When using Database Organizer to unload a database from an image copy, using the UNLOADIC=YES control statement, the RECOVER function is invoked:

FUNCTION=UNLOAD,UNLOADIC=YES,UNLAUTH=NO,DBRC=NO,
DBDNAME=dbdname

RECOVER is then invoked by DBO using these options:

FUNCTION=RECOVER,DBD=dbdname,
DDNAME=ddname,
ICDDNAME=icddname,
UNLOADIC=YES,BYPASSCA=YES,LASTIC=YES,
DBRC=N

Why is the RECOVER function invoked in order to perform an unload?

Resolution

The Unload process when UNLOADIC=YES is specified is as follows:

• The database datasets are recovered from image copies into dataspaces.
  
  
• For HIDAM : the primary index is created in a dataspace.
  
  
• The unload process reads the data from the dataspaces and, when complete,
  deletes the dataspaces.
  
  
• The unload file is created.

Note that neither the actual database nor DBRC are updated by the process.