Preparing for an anticipated increase in IDMS data
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Preparing for an anticipated increase in IDMS data

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Article ID: 33195

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Updated On:

Products

IDMS IDMS - Database

Issue/Introduction

There may be situations in which there is an anticipated increase in database size and the amount of processing that change will require. If possible, it is best to plan proactively for this type of change.

 

Environment

Release: All supported releases.

Resolution

The first thing to do in preparing for an increase in the size of a database is to get as accurate an estimate as possible of the size of the anticipated change. This is likely to be identified as an additional number or percent of record occurrences, for one or more record types. Then use that information to identify the area(s) where the data is stored, and to check them for space availability. The second-tier things to check are:

  1. Index efficiency;
  2. Records that are stored via; and
  3. Other physical factors that could influence performance.

The best place to start this assessment is with a general review of statistics. Use the DCMT DIS STAT SYS command, checking for the following:

  1. On a typical day, are there any deadlocks, or does the system hit MAX TASKS?
  2. Are there any CALC or VIA overflows? Or Buffer waits?
  3. Under indexing statistics, are there any splits or spawns? 

Any of the above could mean that the database needs to be tuned. Remedy any existing problems first, then repeat these steps after the new records are loaded to ensure that the additional records have not compromised system efficiency. 

Use various reports produced by IDMS Performance Monitor (PERFMON) to assess the current efficiency of the database functioning. Detailed instructions on how to do this are listed in the knowledge documents referenced below.

If the system relies heavily on indexes to access important records efficiently, use the PRINT INDEX utility to check the indices defined on those records. The output can indicate how efficiently the indexes are structured. Thinking of the anticipated increase in the number of record occurrences, it is prudent to run some calculations to see if the IBC count of those indexes should be changed to accommodate this increase. If the calculations indicate that a change is warranted, the indices should be rebuilt with that IBC count, allowing free spaces in the indexes, before loading the new records. Complete instructions on how to calculate the most efficient values for the index parameters, see the manual noted below.

 

Additional Information

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