Support for compression?

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Thomas Steinmaurer - 27 Nov 2008 10:25 GMT

Hello,

planning to use SQL Server CE 3.5 on Windows CE 5.0. I wonder if either
SQL CE or Windows CE supports some kind of compression of the database file?

Thanks,
Thomas

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Laxmi Narsimha Rao Oruganti [MSFT] - 01 Dec 2008 04:30 GMT

I am not sure the purpose you are referring to here:

1) Database Level Compression - Like bringing the rows of a table to gether
that are spread over partially filled pages.
Yes this is supported by SQL CE and check the API SqlCeEngine.Compact,
SqlCeEngine.Shrink

2) File Level Compression - Which is more tied with on-media clusters,
sectors, blocks, ...etc
Obviously this is something that Databases are not meant for. It is the job
of file system. So, the next question comes is:

3) Does SQL CE use the special API the file system provides to get
advantage?
SQL CE being designed to work across multiple Windows OS versions (both CE
and desktop) and also designed to work with a wide variety of storage
devices like flash, SD RAM ..etc. So, we are not trying to put some
platform specific code. But I dont know if this stops the application from
benefitting from or using those special API on database file. Also, right
now I don't kow the behavior of such file system API and not sure how that
effects the database on-media pages, format. This is a very important point
as file system does not know the database format and it should be very
carefully considered, investigated before using such API.

Thanks,
Laxmi

> Hello,
>
[quoted text clipped - 4 lines]
> Thanks,
> Thomas

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Thomas Steinmaurer - 01 Dec 2008 07:05 GMT

Hi Laxmi,

thanks for your reply.

I rather thought about something transparent for the user/developer like
compression in NTFS. For example, when I put a database file into a
compressed folder on a NTFS file system, the size on disk is smaller and
I don't have to worry about compressing / decompressing.

So far, I know pretty much zero about filesystems on Win CE, so the
above might be a stupid question / scenario. I'm sorry about that. ;-)

Thanks for any additional pointers you can give.

Thomas

> I am not sure the purpose you are referring to here:
>
[quoted text clipped - 31 lines]
>> Thanks,
>> Thomas

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Laxmi Narsimha Rao Oruganti [MSFT] - 01 Dec 2008 09:59 GMT

Windows CE seems to support compression at file system level. http://msdn.microsoft.com/en-us/library/ms885413.aspx

I would suggest you to try your luck in Windows CE newsgroup "microsoft.public.windowsce.embedded"

You may want to have a look at http://msdn.microsoft.com/en-us/embedded/aa731160.aspx .

Thanks,
Laxmi

> Hi Laxmi,
>
[quoted text clipped - 47 lines]
>>> Thanks,
>>> Thomas

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