Hi,
I wonder whether it is because the instances change the schema of the
database or because they do it simultaneously ? Maybe if you implement a
simple locking mechanism it would work ?.. The simplest way, which I
never tried in Rev, but many times in Perl when programming multiuser
shared flat file based solutions is using a semaphore file.
When an instance of app needs to write data to a shared flat file it:
1) checks if semaphore file (an empty file with known name, e.g anything
like "busy.sem", "busy") is present
2) if it is present it waits and returns to 1) in a few milliseconds
otherwise it
3) creates the semaphore file and writes data into the shared file
4) then deletes the semaphore
All the best!
Viktoras
Dave wrote:
Hi,
The problem with my Application is that whole Tables can be renamed or
deleted. Just tried running two apps at the same time accessing one
database and it instantly crashed and the database is in pieces!
All the Best
Dave
On 14 Feb 2008, at 13:30, viktoras didziulis wrote:
Hi Dave,
in one of my applications I use shell to communicate with sqlite for
data .import and revolution's sqlite to query and modify the same
database. It was never corrupted... Maybe just because .importing and
modification are sequential and do not attempt to modify the same
database in the same time.
I am frequently using an instance of commandline sqlite and an
instance of sqlitespy for some database tests - it possibly can
corrupt the database, but so far this has never happened.
Accessing the same sqlite database should not make any big troubles
unless both sqlite instances modify the database simultaneously. In
this case you may try implementing some sort of locking mechanism.
But then the solution with file would be simpler.
I did a test with a very very simple sqlite app - it did not corrupt
the database even if many instances of it were running... So you can
read, insert or delete a record in a table with one instance and read
it with another and vice versa... But I guess there are scenarios
when the database can get corrupt.
The zipped folder with both the compiled app (for Windows) and the
source can be downloaded from:
http://ekoinf.net/soft/SQLiteTest.zip
Best wishes
Viktoras
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