>We are considering the possibility of changing an existing system to C/S. Pressumably for Microsoft SQL Server, but I believe that doing the upgrade, it should be possible to make it flexible enough so that the database can be on virtually any database server.
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>I have never done this before, but from some reading, I believe I have an idea of what is required. For now I don't want specific technical details, but just a time estimate from people who have done this before. I haven't seen the system in detail yet, but I will make a few assumptions:
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About 140 tables.
>The system has about 100 forms - between data forms and forms for reporting options.
>Parts of the system were programmed with Visual ProMatrix, and we will continue using Visual ProMatrix. However, I think it is safe to assume the previous programmers did not make full use of all VPM capabilities.
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>Any estimate - even if it covers a wide range - will be appreciated.
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>I had given a preliminary estimate of "weeks or even months". My main concerns are that commands that rely on permanent indices (such as SEEK) can no longer be used, and that a USE for a large table will have to be redesigned to fetch only a subset, for efficiency reasons.
On all migrations I have done to SQL Server, I never had to adjust the data model in regards to large table. If you have some in VFP, you should have them as is on SQL Server.
Yes, whatever is SEEK and related proprietary database commands in VFP will have to be adjusted accordingly to a C/S environment.
I have Web site application components spreaded across multiple servers. The Web site can be on several servers (domain routing), the database can be on another server, the robot and Web Services on others and so on. C/S environment will allow you to scale that as is. I do not know if yours is Web driven. Otherwise, as for a desktop application, the same would apply, which is the possibility to isolate your data server into a specific server.
The biggest adjustment is as you mentioned, thus the adjustment of proprietary commands to fit the new environment. Other important tasks will include the migration procedures, the scripts, the testing environment as well as a major rewriting of the code to fit the new environment. I have done some migration to that backend in weeks. Depending on the size of the database and maybe some adjustment in the data model, if required, I was able to do this task for some projects in two weeks and some other in two months.
