RPG IV extension regarding license program 5770SS1-27-DB2-Multisystem

RPG IV provides a file information data structure with database specific feedback information. In position 397 of the FIDS there is an unsigned integer field for the relative record number. This field contains the RRN of the record which was affected by the last I/O operation. With this field it is possible to uniquely identify every record in an ordinary file. In case you use the license program DB2 Multisystem and you create a partitioned table it is no longer possible to identify a record uniquely only with the RRN in position 397 of the FIDS. We need an additional field in the FIDS which specifies the member of the physical file the record belongs to. With the both fields member and RRN it would be possible to identify a record uniquely in a partitioned table.

There are more and more IBM i shops outside who have files with hundreds or even billions of records in a file. If such a file needs to be changed, e.g. a new field has to be added, you can do this by the commands CHGPFM or ALTER TABLE. The problem with this commands is, that the files are exclusive locked as long as the commands are running. This means the users cannot work with their application. Depending on the amount of the records in the file there could be a downtime of the application of hours or even days. Today a lot of companies are working 24 hours a day and 7 days a week and there is no time frame for such a installation. Because of this we created the open source project "Rapid Fire". Here is the link. https://rapid-fire.sourceforge.io/index.php. With Rapid Fire it is possible to reduce the downtime of your application to minutes instead of hours or days if you have to change a file with hundreds or billions of records. The technique behind the scene is described here https://rapid-fire.sourceforge.io/help/ in section "Deploying Data File Changes With Rapid Fire". Rapid Fire works great for ordinary physical files but not for partitioned tables. To make Rapid Fire work for partitioned tables it is necessary to have additionally the member in the file information data structure.