Introduction to the Sequential Subset Randomizer
You can use the Sequential Subset Randomizer to create a randomizing module which enables fast sequential processing of database records belonging to a subset.
The Sequential Subset Randomizer utility is used to implement databases that combine:
- Fast random online access provided by HDAM
- Fast sequential processing of all database records belonging to one or multiple subsets of database records
- Storing all database records of a subset close together in the HDAM root addressable area
- Allowing the retrieval of the first database record of a subset
With the Sequential Subset Randomizer, all database records of subset n are stored before the database records of subset n+1. During sequential database processing, all database records of subset n are retrieved before database records of subset n+1. However, the database records of a subset are neither stored nor retrieved in their logical key sequence.
If a database consists of 20 subsets, the sequential retrieval of all root segments with the Sequential Subset Randomizer will require one 20th, on the average, of the elapsed time which is required with the standard IMS DFSHDC40 randomizer (hereafter, called DFSHDC40).