Ansicht
Dokumentation

CPI4331 - &6 tasks used for parallel index created over file &1. ( OS/400 )

BAL_S_LOG - Application Log: Log header data   rdisp/max_wprun_time - Maximum work process run time  
This documentation is copyright by IBM.


Message : CPI4331
&6 tasks used for parallel index created over file &1.

Message Long Text :

Cause . . . . . : &6 is the average numbers of tasks used for an index created over member &3 of file &1 in library &2.
If file &1 in library &2 is a logical file, then member &9 of physical file &7 in library &8 is the actual file over which the index is being built.
A file name starting with *QUERY or *N for the file indicates a temporary result file is being used.
The query optimizer has calculated that the optimal number of tasks is &5 which was limited for reason code &4. The definition of reason codes are:
1 - The *NBRTASKS parameter value was specified for the DEGREE parameter of the CHGQRYA CL command.
2 - The optimizer calculated the number of tasks which would use all of the central processing units (CPU).
3 - The optimizer calculated the number of tasks which can efficiently run in this job's share of the memory pool.
4 - The optimizer calculated the number of tasks which can efficiently run using the entire memory pool.
The database manager may further limit the number of tasks used for the parallel index build if either the allocation of the file's data is not evenly distributed across disk units or the system has too few disk units.
Recovery . . . : To disallow usage of parallel index build, specify *NONE on the query attribute degree.
A larger number of tasks might further improve performance. The following actions based on the reason code might allow the optimizer to calculate a larger number:
1 - Specify a larger number of tasks value for the DEGREE parameter of the CHGQRYA CL command. Start with a value for number of tasks which is a slightly larger than &5 to see if a performance improvement is achieved.
2 - Simplify the query by reducing the number of fields being mapped to the result buffer or by removing expressions. Also, try specifying a number of tasks for the DEGREE parameter of the CHGQRYA CL command as described by reason code 1.
3 - Specify *MAX for the query attribute degree.
4 - Increase the size of the memory pool.
For more information, refer to the DB2 for i - Database Performance and Query Optimization topic collection in the Database category in the IBM i Information Center.
Technical description . . . . . . . . : Parallel index build can only be implemented when the system feature DB2 Symmetric Multiprocessing is installed on the system.

Message File : QCPFMSG
Library Message File : QSYS2924


Addresses (Business Address Services)   SUBST_MERGE_LIST - merge external lists to one complete list with #if... logic for R3up  
This documentation is copyright by IBM.

Length: 3266 Date: 20240420 Time: 020344     sap01-206 ( 4 ms )