Hi,
I think it's easier to use TCP to communicate rather than try to hack
something to together that wasn't really designed for the job. The
problem is that I'd have to lock the database for very long periods
(10 to 15 minutes or more), and so I'd lose whatever gain was to be
had by splitting the apps. In fact I may as well just implement it as
a single app which is what I have now!
All the Best
Dave
On 15 Feb 2008, at 12:21, viktoras didziulis wrote:
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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