MAINT parameter comparison

 

This table compares the effect of the immediate, rebuild, and delayed maintenance of access paths on opening and processing files.

Function	Immediate maintenance	Rebuild maintenance	Delayed maintenance
Open	Fast open because the access path is current.	Slow open because access path must be rebuilt.	Moderately fast open because the access path does not have to be rebuilt, but it must still be changed. Slow open if extensive changes are needed.
Process	Slower update and output operations when many access paths with immediate maintenance are built over changing data (the system must maintain the access paths).	Faster update and output operations when many access paths with rebuild maintenance are built over changing data and are not open (the system does not have to maintain the access paths).	Moderately fast update and output operations when many access paths with delayed maintenance are built over changing data and are not open (the system records the changes, but the access path itself is not maintained).
Notes: Delayed or rebuild maintenance cannot be specified for a file that has unique keys. Rebuild maintenance cannot be specified for a file if its access path is being journaled.

 

Parent topic:

Specifying the access path maintenance (MAINT) parameter