18.4.6 HSKC Parameter

The HSKC=Y parameter may be specified (or defaulted) on the X_RUN command

When this value is used, "High Speed Key Checking" is enabled. This feature should only be used for Windows or Linux platforms.

When this parameter is enabled, all eligible FILECHECK RDML commands and OAM based "File Lookup Checks" will automatically track key values that have previously been found to exist in the associated SQL table(s). These tracked key values are held in memory and are much faster to (re)access second and subsequent times.

By using the HSKC= parameter selectively on relatively static decode and validation tables you can significantly improve the performance of an application.

For example, there may exist an SQL table called COMPANY that contains the identifiers of all valid companies within your application. Many other SQL tables such as CUSTOMER, ORDER, PRODUCT, etc. may have referential integrity checks against the COMPANY table that are invoked whenever information is inserted, updated or deleted.

When performed under SQL, these lookup checks into COMPANY are relatively expensive, but with the HSKC=Y parameter, all (re)checks of the same key value (i.e. the company identifier) against the COMPANY table are much cheaper and faster to execute.

Typically, eligible files include relatively static tables such as "Company Names", "Zip Codes", "Currency Codes", etc. that are used extensively for validation.

Before using this facility you should be aware of the following:

High Speed Key Checking for OAM based 'File Lookup Checks' is relevant for Windows and Linux platforms only. That is, if the server is a Windows or Linux server then this parameter is relevant. It is not relevant for a Visual LANSA to IBM i set up. However, for FILECHECK RDML commands, the Visual LANSA IBM i set up is fine. If you want to speed up the static files on the IBM i, then you should use the 'High Speed table' option on these files. This should yield a significant improvement in performance.