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Re: Extended Attribute Support (was Re: Mac OS X "resource fork" support)

From: Branko Čibej <brane_at_xbc.nu>
Date: 2005-08-13 21:56:51 CEST

Eric Gorr wrote:

> Branko Čibej wrote:
>> There are many filesystems that don't support extended attributes or
>> several data streams per file.
> Which is entirely irrelevent.
> Again, based on my understanding, support for extended attributes will
> be 'increasingly useful'. If some file system does not support such
> things, it really isn't a problem...subversion can just not look for
> such things on those file systems.

Yes, but it must represent them somehow in the working copy.

>> I don't think you can use properties for xattrs at the moment. The
>> practical constraints on property sizes are much stricter than on
>> file contents.
> I am curious, why are the constraints on property sizes 'practical'?
> Why would it not be reasonable to increase the allowed size?

It's due to how properties are stored in the repository, and how they're
transmitted to the client. Fixing the first part would require an
incompatible change to the FS schema, which implies svn-2.0. I'm not
sure the second part can eve be fixed within the WebDAV protocol.

> If it is not practical to use subversion file property features, then
> I suppose some other method would be needed to better support large
> sized file metadata.
> The point is, there is someone willing to volunteer to implement this
> extremely useful feature for those filesystems which do support
> extended attributes. It is the sole reason why using subversion is not
> practical at least in my specific case.

Well, we can always talk about specific design and implementation
issues. But this will touch almost every part of SVN, from the
filesystem to the working copy management code. I'm not saying "no" to
the idea, I'm just warning you that it's far from trivial.

Of course, if you can live with the current "practical" size limitations
(and I don't know what they are -- we'd have to try and see), then you
can certainly use properties to store extended attributes.

-- Brane

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Received on Sat Aug 13 21:57:41 2005

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