Subject Re: [ib-support] Database grows rapidly (3 to 770MB) when using BLOB views/UDFs
Author Lista de Discução Interbase
There is another aproach.

You could create User Defined Functions in Crystal, so you could make the
converter (EMF -> BMP) as a crystal external function (I can't remeber the
correct "crystal" name).

I really never did an external function in Crystal, but I remember that
it's possible, so, you could change the target for your function.


Alexandre Benson Smith
THOR Software e Comercial Ltda.
Santo Andre - SP - Brazil

At 08:18 18/03/02 +0000, you wrote:
>Hi Everyone,
>My database needs to store a number of images (diagrams) for viewing
>with an application and printing with Crystal Reports. The best
>format to store the images is EMF (Windows vector graphics) in a BLOB
>field which allows good scaling for the on-screen display and also
>produces relatively small BLOBs (compared to colored BMPs).
>However, Crystal Reports is unable to print EMFs directly, so - with
>the help of this group - we figured out a way to convert the EMFs
>into BMPs 'on demand'.
>The solution uses a custom UDF MakeBitmap that takes a BLOB
>containing the EMF and produces a BLOB containing the BMP. The
>declaration is as follows:
>The additional 'double precision' is just a scaling factor.
>To access the BMPs, we have created a view to convert the EMFs into
>BMPs as follows:
> "KIND",
> "DATA"
>) AS
> sampleGroupID, kind, ProPXMakeBitmap(data,1.5)
> SampleAttachment
>WHERE format='EMF'
>So far, everything is fine. The solution works, so we have created a
>report printing the diagrams.
>However there is a severe disadvantage. After using the system for a
>few hours, we discovered, that the initial database (3MB) had grown
>to amazing 770MB although we didn't insert a single record. Backup
>and restore shrinks the DB back to 3 MB, but sweep does not do
>I have read about the oldest transaction, etc. so take the following
>In IBConsole, I tried
>select * from sampleattachmentbmp
>which gives a result of 10 rows with the BMP images. Afterwards, I
>did a commit from the transaction menu. I am the only user, so to my
>mind there is no transaction pending.
>These steps grew the database from 3 to 180 MB!!
>I should add that the system is supposed to run 7x24h unattended, so
>this really is a killer bug/feature.
>Anyone has any hints?
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