Serial and binary search in cobol


But the compiler writers cannot read your mind and occasionally you may have issues with runtime performance efficiency. Most performance problems are caused by poor design. These problems can sometimes be corrected with simple coding changes. In extreme cases runtime performance can only be improved with a major rewrite.

Another indication may be response time in excess of one second for a CICS online program. Even if CPU utilization seems normal, you may have a runtime performance problem if a job simply takes too much time, and prevents the daily batch cycle from completing in less than 24 hours.

I have heard it said that there are only two ways to improve runtime performance: Or in simpler terms, don't do any work you don't need to do. Avoid multiple passes against the same file, if possible. Try not to tie up too many tape drives in a single job step. If your program needs 10 tape serial and binary search in cobol, it will wait until all 10 drives are available. Try to keep files on disk whenever conveniently possible. Even with external sorts, tape access, and multiple steps, the CPU will do less work.

If performance is absolutely critical for your application, don't be afraid to test alternate designs. That means a hour job can complete serial and binary search in cobol one hour. Here are some tips for writing efficient procedure logic: When performing arithmetic, always use signed numeric fields. COBOL performs faster with signed fields than unsigned fields.

Arithmetic will be faster on binary fields than on packed-decimal fields, but not by much. Be sure your numeric fields are wide enough to avoid truncation of intermediate results. It will also perform your arithmetic with packed-decimal numbers instead of binary numbers. Test for these conditions early. That bypasses all the logic to test for the less common situations.

Any code that is iterated will adversely lengthen your instruction path if it includes instructions that do not need to be executed. This is particularly important with table searches. A serial search of a entry table is very inefficient, especially if it is performed for every serial and binary search in cobol record and your file has 10 million of them. Testing alternate designs will help identify which approach improves efficiency.

Sometimes it may be helpful to examine the disassembled code generated by the compiler. In my experience, optimizing your loops and table searches will make the biggest gains. Many years ago I assisted another programmer in an all-night session, building some one-time reports. We wrote a program that serial and binary search in cobol a large file.

For each record, a table was serially searched to look up customer information. The input file was large, and the customer table had over entries. We cancelled that program after one hour, because it would not finish in time. Looking at the program, we realized that the input file was in sequence by customer number.

A simple test was added to see if the current customer number matched the last customer number searched for, allowing the table search to be bypassed. The modified program completed in five minutes. Recently I worked on a production program that was having a performance problem. The program ran for 10 hours and used almost 10 hours of CPU time. For each of 15 million input records, a table with about entries was searched serially.

I modified the program to use a binary serial and binary search in cobol rather than a serial search. Efficient runtime performance results from good analysis and serial and binary search in cobol, but many performance problems can be repaired with relatively simple changes. I would like to read it, and perhaps include it on this page. Klein Click Here to return to my home page.

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