losing data

[Ivan Smahin]

On 12/24/2010 3:14 PM, william humphrey wrote:
> Did the re-install and I'm still losing data whenever there is a crash 
> or anything other than proper shut-down from LiveCode. I think maybe 
> you added a feature that rolls back data to the last proper close of 
> database?
>
>
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> Valentina-beta mailing list
> Valentina-beta at lists.macserve.net
> http://lists.macserve.net/mailman/listinfo/valentina-beta

Well, as far as I understand...
You are running vServer. And your app (livecode app) connects to that 
vServer,
do some inserts, updates, deletes against some database on that vServer.

Assume your app issues some "insert into t1 values..." sql statement.
Your app is passing this command to the vServer. vServer, in turn,  pass 
it to the vKernel level,
and vKernel performs the actual job.
But inserted values don't come to the disk immediately - it would be too 
slow!
They come to some internal valentina cache instead (it is absolutely 
transparent process - no difference
is data flushed to the disk or not. The data is available to your app 
anyway.)

There are two cases when the data comes to the disk:
1. Flush command issued (Pay attention to auto-flush vServer mode - see 
vServer's ini settings)
2. Internally flushed (because of db is closed, no space in the cache 
which requires to flush dirty pages and so on...)

So if something bad happens (like crash or kill vServer) some data may 
not be flushed to the disk and next start you
see no such data in the db.
Also pay attention that your app just provide commands and receives 
results to/from vServer - so your app's crashes,
hangs and so on means nothing to the db state.

Also, I don't understand - why do you restart computer?
Assume your app hangs -  just kill it. You don't need to kill vServer 
and moreover to restart computer.

-- 
Best regards,
Ivan Smahin
Senior Software Engineer
Paradigma Software, Inc
Valentina - The Ultra-Fast Database
http://www.valentina-db.com

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