Correct DB location on Win XP/Vista

[Ruslan Zasukhin]

On 12/2/06 11:42 PM, "Pierre Rossel" <agora07 at prossel.com> wrote:

Hi Pierre, 

>> May be you have see this on Mac OS X ?
> 
> No. Just tested again right now to be sure (Windows XP Pro). Even with two
> instances of Vstudio, on the same base (the last one that opens
> automatically). No message.

Strange. We will check this issue.
May be eve should be added into Mantis.

Db files are not marked as Read Only ?!


>> Yes it do, this is one of reasons why it is 1000+ times slooooower of
>> Valentina :-)
> 
> Just keep your fastness for now... :-)
> 
> But I'm sure if you really wanted to support shared access, you won't be
> 1000+ slower. The trick is to have a cache for each app/user but a mechanism
> to invalidate it when concerned data is modified. So it will only be slower
> when the cache is no longer valid and has to be rebuilt.

First of all, to implement shared access, software must use OS API to lock
parts of disk file, from byte N to N+n. Its the whole task.

Mechanism which you mention - ability to recognize changed records and what
next? Send active notification to all other client computers??? Not
effective. Wait passive? Then Client computer must check each cache page of
disk file before next operation? Not effective.

This is why as far as I know, all such dbs just not use cache, they load one
record at time probably. Lock its space in disk file.

The worse thing here is work with indexes. Computer1 want do search of index
of field f1. It must load page by page of index file from "shared-server"
computer into RAM of client, do search on page, then load next.

No no no. bad games :-)

-- 
Best regards,

Ruslan Zasukhin
VP Engineering and New Technology
Paradigma Software, Inc

Valentina - Joining Worlds of Information
http://www.paradigmasoft.com

[I feel the need: the need for speed]