Zipping Data Base file

[Guest]

I have used Zipping on many occasions to enable Emailing of a Data Base. I
have noticed that a new Data Base file I have designed when zipped reduces
only marginaly in size, by only a few k's. The file is approx. 8Megs.
Can any one tell me how this can be corrected. I have used Compact & Repair
prior to Zipping
Thanks for any help

 

[Guest]

Hi Roger,

If you are developing with the Access 2002-2003 file format, you may want to
convert to the Access 2000 file format, unless you have functionality that is
only supported in the later file format.

Try decompiling your VBA code and then perform a compact and repair. You can
use the following *if* you only have one version of Access installed on your
PC: Click on Start > Run, and enter the following command:

msaccess /decompile

The next database you open will have it's code decompiled. If you have
multiple versions of Access, then I recommend creating a shortcut for each
version that includes the undocumented /decompile switch. To read more about
this option, check out Michael Kaplan's page:

http://www.trigeminal.com/usenet/usenet004.asp?1033


Sometimes creating a brand new database will help reduce the size. Here is
my boilerplate advice on the subject for correcting minor corruption; the
same technique often times reduces the file size:

Create a brand new database and immediately disable the NameAutocorrupt
feature (see: http://allenbrowne.com/bug-03.html for reasons why you want to
do this). Then import all objects from the suspect database into the new
database, one group at a time. In other words, import all tables (but not
linked tables), then import all queries, then all forms, etc. While Access
will allow you to import all objects in one operation, the experts at FMS,
Inc. (a Microsoft Partner), have stated that it is best to import objects one
group at a time (Reference:

http://www.fmsinc.com/ubb/Forum12/HTML/000285.html).

Recreate any linked tables from scratch. Access can cache a lot of
information about linked tables, which may no longer be valid, so it's always
best to recreate the linked tables from scratch. When importing local tables,
make sure to check the option to import relationships, menus and toolbars,
and import/export specs. If any of the local tables in the source DB are
hidden, you'll need to first unhide them. You will need to set the checked
references to match the source database, along with any startup options set
under Tools > Startup. Going through this process often times solves
corruption problems, because you get a new set of the hidden system tables
(the tables whose names start with "MSYS"). These system tables are updated
appropriately as you import objects.

This may sound like a lot of work, but it really isn't. Creating a new
container DB, disabling NameAutocorrect, importing all objects one group at a
time, re-establishing any linked tables, setting startup options, and setting
references to match the source DB is usually a fairly quick procedure. When
you are in the Visual Basic Editor, in order to check that the references
match the source DB, you should do a Debug > Compile ProjectName as well.

If none of the above helps, then your database is likely about as small as
it will be with the current set of objects and data.


Tom Wickerath
Microsoft Access MVP

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

 

[Guest]

Thanks for that Tom.
Useing Access 2003. Tried what you suggested, but made no difference.
Have since used "Tools-Security-Encode/Decode Data Base" which alllowed the
zipping correctly. Will there be any implications to the Data Base as a
result of using this feature? Naturally, I have the original copy prior to
Encoding/Decoding
Many Thanks

 

[Guest]

Hi Roger,

Have since used "Tools-Security-Encode/Decode Data Base"...

Did you mean Tools > Security > Encrypt/Decrypt Database...?

If so, and if you had previously encrypted your database, then I'm not sure
if a zipping utility could compress that. If you then decrypted it, WinZip,
or any other similar utility certainly should be able to pack that file, at
least to some extent.

Encryption helps to prevent snooping eyes from attempting to look at data by
opening the .mdb file with a hex (or text) editor. There is a slight
performance hit for encrypting your data, because this encrypt/decrypt
process must go on constantly in the background.


Tom Wickerath
Microsoft Access MVP

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

 

[Guest]

Thanks again Tom
The version I am using is Access 2003, part of Office Professional and under
the Tools Menu-Security, the last option is "Encode/Decode Data Base".
I am not sure what this actually does and would be grateful for any
enlightenment.
There is not an option here for Encrypt/Decrypt. Perhaps they mean the same
thing!
Thanks again

 

[Guest]

Hi Roger,

Arrrggghhh (as Charlie Brown would scream, as Lucy jerks the football away).
I now see the "Encode/Decode Data Base" option that you mention. I had
Access 2002 open previously. I guess someone at Microsoft felt there was
value to changing the terminology between versions. Yes, Encode/Decode and
Encrypt/Decrypt mean the same thing.


Tom Wickerath
Microsoft Access MVP

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

 

[Guest]

PS. As an experiment, try making two throw-away copies of your database.
Encrypt, er encode, one of them. Then open them using WordPad, and arrange in
a side-by-side view. You will see that in the original (unencrypted) version,
that there are certain data values that you can read, simply by scanning the
file. You won't be able to read the same area of the encrypted file.


Tom Wickerath
Microsoft Access MVP

http://www.access.qbuilt.com/html/expert_contributors.html
http://www.access.qbuilt.com/html/search.html
__________________________________________

 

[Arvin Meyer [MVP]]

Because you are encrypting the database, you will only get a minor amount of
compression when zipping. Zip programs rely on patterns to delete characters
to compress the file. Encrypting a database destroys any discernable
patterns.

You might try using WinZip 9.0 or later which can encrypt the file after
zipping, instead of before. Winzip uses AES encryption (both 128 and 256
bit) which is virtually uncrackable.