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

Document ID : KB000053666
Last Modified Date : 14/02/2018
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Description:

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?

Solution:

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.