[Zope3-dev] Re: IKeyReference for files

[Uwe Oestermeier]

Martijn Faassen <faassen at startifact.com> schreibt:
>Yeah, and I do need to be cross-platform with this, so inodes are not
>ideal.

Hi, 

it depends on how cross-platform you need to be and whether you have
another solution that is ideal;)

For Win32 you can use the low value of the FileIndex number of the
filesystems master file table. This is the last value of the (10-)tuple
returned by the Win32 API method

	win32file.GetFileInformationByHandle()

Note that the new Blob-support also uses win32file

Concerning the problem of the different filesystems and devices I can only
guess whether your use cases really need to take different devices into
account. In our use case we simply assumed that the files are on a single
device and remain were they are. If you follow Christian's suggestion of
using hard links with the oid of a shadow object in the ZODB a similar
restriction applies.

In any case I'm also interested in IKeyReferences for files, so I hope
that there is a better solution that is cross platform, allows an
efficient lookup, works across devices, and offers also an easy way to
detect catalog relevant changes. I fear there is no ideal solution to all
these problems and we need to consider trade-offs.

Regards,
Uwe

________________________________________________________________
Dr. Uwe Oestermeier
Institut für Wissensmedien
Knowledge Media Research Center
Konrad-Adenauer-Str. 40
D-72072 Tuebingen
Germany
u.oestermeier at iwm-kmrc.de
Tel. +49 7071 979-208
Fax +49 7071 979-100