CHECK LOB

You can run the CHECK LOB online utility on a LOB table space to identify any structural defects in the LOB table space and any invalid LOB values.

The CHECK LOB utility is useful in a variety of circumstances:

Run the utility on a LOB table space that is in CHECK-pending (CHKP) status to identify structural defects. If none are found, the CHECK LOB utility turns the CHKP status off.
Run the utility on a LOB table space that is in auxiliary-warning (AUXW) status to identify invalid LOBs. If none exist, the CHECK LOB utility turns AUXW status off.
Run the utility after a conditional restart or a point-in-time recovery on all table spaces where LOB table spaces might not be synchronized.
Run the utility before you run the CHECK DATA utility on a table space that contains at least one LOB column.

Output

After successful execution, CHECK LOB SHRLEVEL CHANGE does not set or reset the CHECK-pending (CHKP) and auxiliary-warning (AUXW) statuses.

Start of change If the utility finds any inconsistencies, the LOB table space that is checked is not put into the CHECK-pending status. You can force the prior behavior, that a LOB table space is put into CHECK-pending status when inconsistencies are detected, by specifying CHECK_SETCHKP=Y on the CHECK_SETCHKP system parameter. End of change

Authorization required

To execute this utility, you must use a privilege set that includes one of the following authorities:

STATS privilege for the database
DBADM, DBCTRL, or DBMAINT authority for the database. If the object on which the utility operates is in an implicitly created database, DBADM authority on the implicitly created database or DSNDB04 is required.
System DBADM authority
SYSCTRL or SYSADM authority

An ID with installation SYSOPR authority can also execute CHECK LOB.

If you are using SHRLEVEL CHANGE, the user ID that invokes COPY with the CONCURRENT option must provide the necessary authority to execute the DFSMSdss ADRDSSU command. DFSMSdss will create a shadow data set with the authority of the utility batch address space. The submitter should have a RACF® ALTER authority, or its equivalent, for the shadow data set.

Execution phases of CHECK LOB

The CHECK LOB utility operates in the following phases:

UTILINIT: Performs initialization
CHECKLOB: Scans all active pages of the LOB table space; generates up to four records per LOB page; passes records to the SORTIN phase
SORTIN: Passes CHECKLOB phase records to SORT
SORT: Sorts the records from the CHECKLOB phase
SORTOUT: Passes sorted records to the REPRTLOB phase
REPRTLOB: Examines records that are produced by the CHECKLOB phase; issues error messages
UTILTERM: Performs cleanup

Syntax and options of the CHECK LOB control statement
The CHECK LOB utility control statement, with its multiple options, defines the function that the utility job performs.
Before running CHECK LOB
Certain activities might be required before you run the CHECK LOB utility, depending on your situation.
How CHECK LOB identifies violations
You can find and resolve violations by reviewing messages that the CHECK LOB utility issues.
Removing CHECK-pending status for a LOB table space
If a LOB table space has a status of CHECK-pending, you can remove the CHECK-pending status by correcting the error and either rerunning the CHECK LOB utility with SHRLEVEL REFERENCE specified or by running the REPAIR utility.
Resolving media failure
Some media failures leave LOB pages in the logical page list (LPL), which requires action.
Termination or restart of CHECK LOB
You can terminate and restart the CHECK LOB utility.
Sample CHECK LOB control statements
Sample control statements are helpful as models for developing your own CHECK LOB control statements.

Parent topic: DB2 online utilities