It is a fact that accessing a data base table instead a VISION file, the performance decreases due to VISION files are the native file system handled by Extend runtime with no translations at all. This performance hit increases if the program is accessing the tables using alternate keys; data bases don’t have and don’t know the alternate key’s concept.
In Cobol, the two most expensive statements, in terms of performance, are OPEN and START; accessing a VISON file this impact is not noticeable but it is when we are working with a data base.
Using the above COBOL statements extensively in the same program or in the same runtime unit will decrease the performance of the runtime.
Said that, there are some guidelines described in Chapter 9 Performance and Troubleshooting; 9.1 Performance Issues; 9.1.1 Guidelines in our Acu4GL User's Guide.
There is an emphasis in The Where Constraint which allows to improve performance in some situations.
In addition to the WHERE constraint, there are some Acu4GL configuration variables that can improve performance. They are:
Users need to read the documentation on each of these to determine whether they apply to their application. Some testing can help determine the best settings. These can all have a dramatic effect on performance depending on what the program is doing.
In addition to that there are two configuration variables to disable locking which users may want to implement if the program is only reading data:
They both have the obvious consequences.