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Thread Detecting LargeFileSupport
Mon, Nov 6 2006 6:28 AMPermanent Link

Is there a way to determine if LargeFileSupport is active or not in a
database? Indeed, how do I know if it is working or not? I just set the
value in the engine, and then ran my code, but the tables verified and it
all worked fine.

Does the format of the file actually change, or is this just a "let it go
over the limit" sort of flag? Maybe I mis-understood what this does. If it
really is as easy as setting a flag and the file format doesn't change,
then I'm away!

/Matthew Jones/
Mon, Nov 6 2006 12:23 PMPermanent Link

Jason Lee
Set the property in the Engine....that's all there is to it.
In fact, if you use C/S you could have the server running on an OS that
supports large files and the clients could still be Win98 machines.

mattjones@cix.co.uk (Matthew Jones) wrote:
> Is there a way to determine if LargeFileSupport is active or not in a
> database? Indeed, how do I know if it is working or not? I just set the
> value in the engine, and then ran my code, but the tables verified and it
> all worked fine.
>
> Does the format of the file actually change, or is this just a "let it go
> over the limit" sort of flag? Maybe I mis-understood what this does. If it
> really is as easy as setting a flag and the file format doesn't change,
> then I'm away!
>
> /Matthew Jones/
Mon, Nov 6 2006 1:52 PMPermanent Link

Excellent! I'd have enabled it years ago if I'd known it was that simple.

Thanks for responding.

/Matthew Jones/
Mon, Nov 6 2006 11:32 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Matthew,

<< Does the format of the file actually change, or is this just a "let it go
over the limit" sort of flag? Maybe I mis-understood what this does. If it
really is as easy as setting a flag and the file format doesn't change, then
I'm away! >>

It doesn't change the file format.  What it does is allow for larger files
by increasing the virtual lock offsets that DBISAM uses internally for
performing locking on the various database files via the OS.  Using virtual
lock offsets past 4 gigs in Windows 9x/ME will cause locking errors because
those OS's don't support anything greater.

--
Tim Young
Elevate Software
www.elevatesoft.com

Tue, Nov 7 2006 4:25 AMPermanent Link

Tim,

Please be sure to add this to the documentation. I'm sure more people
would use large file support if they knew it wasn't something to fear.

/Matthew Jones/
Tue, Nov 7 2006 5:04 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Matthew,

<< Please be sure to add this to the documentation. I'm sure more people
would use large file support if they knew it wasn't something to fear. >>

Well, we never indicate in the documentation that enabling large file
support requires any table changes, hence it was assumed that it would be
taken at face value per the instructions given:

http://www.elevatesoft.com/dbisam4d5_enabling_large_file_support.htm

--
Tim Young
Elevate Software
www.elevatesoft.com

Wed, Nov 8 2006 4:53 AMPermanent Link

I did indeed read, study and digest that page. It was the part that says
"Do not mix [...] large file support enabled with applications [...] that
do not have large file support enabled. Doing so will cause database
corruption [...]" that scared me off. If you read it knowing that the
format is actually the same, and understand the part that follows, then it
is all perfectly reasonable and says it actually only applies to the
locks. But it doesn't say that you can flip the switch at any time you
want so long as all apps are using the same switch setting.

It isn't so much what is said, as what isn't. It confused/scared me off
just flipping the switch to solve my problem, and I was surprised when it
"just worked". It may be I'm just stupid, but that's why I suggested
documenting it a bit more.

/Matthew Jones/
Wed, Nov 8 2006 3:16 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Matthew,

<< It isn't so much what is said, as what isn't. It confused/scared me off
just flipping the switch to solve my problem, and I was surprised when it
"just worked". It may be I'm just stupid, but that's why I suggested
documenting it a bit more. >>

I understand.  I was just pointing out the reason why it wasn't mentioned.

--
Tim Young
Elevate Software
www.elevatesoft.com

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