dbf/cdx Limits

[wriedmann]

Hi Horst,
please see this ticket:
https://github.com/X-Sharp/XSharpPublic/issues/83
It seems this is yet to implement.
Wolfgang

[wriedmann]

Hello all,
since I remembered that some time ago there were some PDF documents with the programmers guide, I have searched my hard disk collection and found something in a VO 2.7 installation.
If you look at this document:
https://riedmann.it/download/VO27pg.pdf
there is an "Appendix A: RDD specifics".
Maybe someone is interested also in the othe documents:
Getting Started Guide: https://riedmann.it/download/Vo27gs.pdf
IDE User Guide: https://riedmann.it/download/vo27ug.pdf
South Seas Adventure Guide: https://riedmann.it/download/Vo27ssa.pdf
But please beware: these documents are from the year 2005.
Wolfgang

[TrevorLE]

Hello all
Just adding a point of interest here - that we use Advantage Database Server with DBFCDX files and we have clients with files sizes of > 4Gig and some control files with 900 fields and it all works with no issues.

I think I read that the there is a plan by the X# team to create a replacement client server RDD of some description that would be along the lines of Advantage - hopefully that would build on what Advantage does (especially since SAP purchased Advantage which is a great product and has let it sit on the shelf !)

cheers
Trevor

[wriedmann]

Hi Trevor,
that is good to hear that ADS can superate the DBFCDX limits!

I don't know it you have read what the development team plans to do: write an RDD that is not more based on DBF files, but on a true SQL server database (my hopes are that at least MS Sql Server and PostgreSQL are supported, and maybe also SQLite for single user setups).
Wolfgang

[robert]

Trevor,

Just adding a point of interest here - that we use Advantage Database Server with DBFCDX files and we have clients with files sizes of > 4Gig and some control files with 900 fields and it all works with no issues.

ADS can do that because it opens the files on its own and it can therefore use a proprietary locking scheme. Of course it need to use 64 bit addresses internally, but that is not a problem. CDX files are still limited to 4 Gb because they use 32 bit addresses internally.
We plan to add support for that in a future build as well.

I think I read that the there is a plan by the X# team to create a replacement client server RDD of some description that would be along the lines of Advantage - hopefully that would build on what Advantage does (especially since SAP purchased Advantage which is a great product and has let it sit on the shelf !)

Yes, SAP has purchased ADS and indeed let it sit on the shelf.
Our plan is create a client server solution for both xbase tables, but more importantly also for SQL tables, so you can use both record oriented and set oriented data access on the same table.
And to be clear: we do not plan SQL based access to xBase tables. We do not want to reinvent the wheel.

Robert

[TrevorLE]

Robert

thanks for the information!

Does that mean with record oriented data access in the new driver, that existing dbfcdx code would work if you converted a dbf to an sql file and opened the sql database using the same object that current dbfcdx code used?
Converting to SQL has always been a big obstacle for us because our system is so large with so many databases etc that re-writing code from dbfcdx style access to sql access would be nearly impossible and would have such a large potential for problems in a commercial app. So the only way I see it being possible would be at a driver level like that if there was a reasonable amount of compatibility for existing code so you could convert it on mass like we did from Vulcan to X#, but I'm not sure how that could work with the differences between dbf seeking and database access versus SQL - but maybe I am misunderstanding what you are saying here.

cheers
Trevor

[robert]

Trevor,
That is exactly what we want to to do.
But let's not get ahead of ourselves. This is still very much work in progress.

Robert

[TrevorLE]

Robert

that sounds awesome if that is the plan !

Thanks for the clarification - I will leave you alone so you can get back to it.

cheers
Trevor