Developing the RDD driver is not an easy task, and the work on RDD driver cooperating with SQL database is even harder. That is the reason why there are not many solutions on the market that enable fast migration from DBF to SQL. Algorithms and methods used by Mediator are a result of many years' experience gathered by OTC and our clients since 1995, when the company was set up. We are convinced that at present Mediator is the most mature product of that type.
In order to enable the products comparing and making the choice, we would like to draw your attention to several elements which decide about the success of xBase application migration to SQL.
1. RDD driver should be as compatible as possible with the one used so far.
The lack of RECNO fixed numbers, xBase-complaisant locks and expression indexes, in practice means very widespread changes in an application, a waste of time on its profound testing and in consequence, a possible failure of the project.
2. RDD driver should be efficient (fast).
Often performed operations should be realized swiftly. The driver performance on big tables is essential and it should be checked. SQL feature causes that the times of executing some SQL queries are proportional to the number of records in a table. That is why some solutions work properly on little data, but they become inacceptably slow when the data grows. In order not to get trapped, it is worth to make a simple test:
- create in SQL database any table 'test' and load into it 1 000 000 (million) records
- start on the table w standard function browse()
- test the performance of browse() while viewing the table, go to the beginning and the end of the table, change the viewing direction many times
If while viewing longer jams occur ( longer than 1 second), it means that SQL commands generated by RDD driver are not optimized in the right way, and that serious effectiveness problems should be expected while working on large data.
SQL commands used by Mediator are optimized individually for every database system supported by us. It provides the best possible software effectiveness.
3. RDD driver should work on-line on the server.
All the operations of
xBase application should be immediately executed on SQL server. Some solutions work on a local table copy or its part. In practice it means vital slowing down of application work and huge problems while synchronizing the data in multiuser environment. A driver may contains extensions allowing to work on local copies, but the basic job must be done directly on SQL server.
