Re: Supporting SQL/MED DATALINK

On Jan 9, 2012, at 5:07 AM, Alban Hertroys wrote:

> On 9 January 2012 09:56, Damiano ALBANI
>>> I believe DB2 is pretty much it in this area.
>>
>> For the record, it looks like MS SQL Server has some equivalent feature :
>> FILESTREAM.
>
> And Oracle has BFILE.
>
> I've actually been thinking about how to implement something like this
> for Postgres, but the interaction with the file-system makes it a
> little more difficult to implement. Someone shouldn't be able to
> delete a file from the file-system that's still referenced from the
> database.
> Perhaps a file-system layer with FusionFS would be a suitable solution
> for something like this, but I couldn't convince myself that it is.
>
> In the end, it probably requires a custom file-system implementation
> that needs maintaining across all operating systems that Postgres runs
> on. That's a major undertaking!
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> If you can't see the forest for the trees,
> Cut the trees and you'll see there is no forest.
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Not sure I see the need to keep the user/system from deleting a database referenced file. BFILEs are created completely outside of Oracle and Oracle will not insert data or write to a BFILE. It seems the reference to the external file is a very weak read only reference as BFILE provides functions like fileExists() and isFileOpen(). They leave it up to the code to determine if the file is available and has the correct permisisons.