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Relational (SQL) access to Btrieve files

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Michale Schwarz
 
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Default Relational (SQL) access to Btrieve files - 08-14-2008 , 08:50 AM






Hi Btrievians!

We’ve got an application primarily accessing data files via Btrieve interface. For some reasons it’s necessary to get read access to _the_same_ ("living") files via relational interface (SQL SELECT statements).
Fortunately the exact structure of our Btrieve files is known and Pervasive supports reusing of files by "in dictionary" and "using" directives. So I can build SQL "files" with something like

CREATE TABLE myTable IN DICTIONARY USING '..\myDir\myTable.btrv' (…)

and

CREATE INDEX myIndex IN DICTIONARY ON myTable (…)

As a matter of principle that works fine so far. But I’ve got the following two problems:

The first problem is that Btrieve application normally runs 24 hours on 7 days a week. Up to now nobody was able to tell me definitively, whether creating SQL "files" while running Btrieve application could cause problems or is safe. Now I had the idea to set Btrieve file to Continuous Operation Mode before performing the above statements. Does anyone (definitively) know whether that would be a safe way to create SQL "file" while Btrieve application is running?

The second problem is that SQL "files" for some of our Btrieve files can’t be created (e.g. because they contain to many columns). In principal that is not a big problem (these files are not so important), but trying to perform the above statements causes bad conditions. In most cases it takes Pervasive a long time to determine, that table can’t be created. That would be acceptable, but sometimes Pervasive really crashes (the complete computer must be restarted). In environment with the need of running Btrieve application all the time this is a very big problem!
Therefore my question: Is there any opportunity to check whether statement will work _before_ performing it with the risk of system crash?

Thanks.

Michael

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