Re: DB/2 index updates

[John Ross <jross-ml@xxxxxxxxxxxxxxx>]

From the help on V5R2 

*IMMED                                                                
   The access path is continuously (immediately) maintained for each 
   physical file member.  The path is changed each time a record is  
   changed, added to, or deleted from the member.  *IMMED is specified
   for all files requiring unique keys to ensure uniqueness in all   
   inserts and changes.                                              

*REBLD                                                                  
    The access path is rebuilt when a file member is opened.  The access
    path is continuously maintained until the member is closed; then the
    access path maintenance is ended.  *REBLD is not valid for access   
    paths that contain unique key values.                               
                                                                        
*DLY                                                                    
    The maintenance of the access path is delayed until the member is   
    opened for use.  Then the access path is changed only for records   
    that were added, deleted, or changed since the file was last closed.
    (While the file is open, all changes made to based-on members are   
    immediately reflected in the access paths of the members of the     
    opened files, no matter what is specified for the MAINT parameter.) 
    To prevent a lengthy rebuild time when the file is opened, *DLY     
    should be specified only when the number of changes to the access   
   path between a close operation and the next open operation are small
   (when key fields in records for this access path change             
   infrequently).  *DLY is not valid for access paths that require     
   unique key values.                                                  
                                                                       
   If the number of changes between a close operation and the next open
   operation reaches approximately 10% of the access path size, the    
   system stops saving changes and the access path is completely       
   rebuilt the next time the file is opened.                           

John Ross

Tom Liotta wrote:

> The surprise was that _every_ combination gave the same result -- every 
> record key had been changed to 0 (zero). I'm pretty sure I understand both the 
> *IMMED and *DLY results, but I'm not certain I understand what happened for 
> MAINT(*REBLD). I suppose the _good_ news is that the results were consistent.
>
> Should the program have seen the changed index so that reading the next key 
> would get the changed record?
>
>