Database jobs

 

This information contains a list of database jobs.

Qdbfstccol (database file statistic collection)

This job collects database file statistics. These statistics are crucial to correct database query optimization.

Qdbsrvxr (database cross-reference) and Qdbx###xr for independent disk pool group ###

This job maintains each of the file level system cross-reference files in Qsys. These files contain cross-reference information about database files and SQL information across the system. The files all begin with the prefix of Qadb in library Qsys. The primary file that must be maintained is Qadbxref, the cross-reference file. This file contains a record of each physical database, logical database, DDM, and Alias file on the system. Qdbsrvxr activates when a file is created, changed, deleted, restored, renamed, or its ownership is changed.

Qdbsrvxr2 (database cross-reference 2) and Qdbx###xr2 for independent disk pool group ###

This job maintains the two field level cross-reference files. Qadbifld in library Qsys is the field cross-reference file. Qadbkfld in library Qsys is the key field cross-reference file. Qdbsrvxr2 is activated when a file is created, changed or deleted.

Qdbsrv01 (database server) and Qdbs###v01 for independent disk pool group ###

This job can be viewed as the database maintenance task dispatcher. The number of database server jobs on the system is one plus twice the number of processors, or one plus twice the number of ASPs, whichever is greater. The minimum started is five. Qsbsrv01 is the main system job assigning work to the others. Typically, Qdbsrv01 will be most active immediately after restoring a library that contains database files. Its function includes:

  • Signaling to the system-managed access path protection (SMAPP) Licensed Internal Code (LIC) tasks that new access paths have been restored. SMAPP then determines whether these access paths need to be protected.

  • Preparing the list of access paths that are required to be rebuilt because the access paths were not restored.

Of the remaining database server jobs, the first half process high-priority requests, and the second half process low-priority requests. (Example: Qdbsrv02 through Qdbsrv05 are high priority, Qdbsrv06 through Qdbsrv09 are low priority.)

Qdbsrvxx (database server, high priority) and Qdbs###vxx for independent disk pool group ###

These jobs perform journal and commitment control maintenance for the system and are considered quick or short-running work.

Qdbsrvxx (database server, low priority) and Qdbs###vxx for independent disk pool group ###

These jobs perform access path maintenance on user data files. Typically, these jobs are inactive, but in certain cases, they might activate to perform access path rebuilds. Some reasons why these jobs might be active are:

  • Restoring database files that were not saved with access paths

  • Restoring logical files without the physical file they are based on

  • Canceling of an Rgzpfm command while in process

  • Invalidation of an index due to damage found in the index

  • Post-iServer installation activity to complete cross-reference or other DB upgrade activity

  • Constraint verification

Qqqtemp1 and Qqqtemp2 (database parallelism)

The database parallelism system jobs perform asynchronous database processing for the DB2 Multisystem. If users query distributed files, the jobs are used to speed up the queries by doing certain tasks in parallel.

 

Parent topic:

System jobs

Related concepts
System startup jobs System arbiters System communication jobs Other system jobs