[Mulgara-dev] CRITICAL: Bug fix to Backup operation

[Andrae Muys]

On 28/03/2008, at 5:05 AM, Ben Hysell wrote:
> We restore to a brand new Mulgara instance that has an empty server1
> directory.

Ok, in this case I am unable to reproduce the 2nd bug discussed below.

Just confirming my understanding of what's going on:

1. You are using the latest mulgara from svn trunk/
2. You backup the mulgara instance - and the resulting backup  
contains blank-nodes
3. You startup a new mulgara instance (pointing at a new directory)
4. You restore the backup produced in 2.
5. You backup the new instance - and the resulting backup has  
replaced the blank-nodes with "_node#####" literals.

I have attempted to reproduce this on my system and failed - I have  
included the two backup files (decompressed) at the end of this email.

If I haven't misunderstood what you are seeing, then I am going to  
need a fuller description of your environment - I hate these sort of  
bugs.

Andrae

FIRST BACKUP (backup1)

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SECOND BACKUP (backup2)

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> On 26/03/2008, at 11:48 PM, Ben Hysell wrote:
>>>> 2. Read through the string pool looking for any entries that start
>> with _node followed by a number
>>
>>> As discussed below, this step should *never* happen - even if you
>>> *are*
>> using blank-nodes.
>>
>> But if a backup has node numbers in the triples section and not in  
>> the
>> string pool and we restore that backup and then query it the query
>> will
>> return "_node######".  If you then backup that Mulgara and look in  
>> the
>> string pool you'll then find: ## "_node######".
>
> That suggests that somewhere in the backup/restore process a blank-
> node has been converted into a literal.  I have just tried to
> reproduce this on a clean image, and haven't been able to do it - so
> all I can suggest is that this is happening as a side-effect of other
> weirdness we are seeing.
>
> Can I ask if you are restoring to the original mulgara instance?  Or
> to a new one?


-- 
Andrae Muys
andrae at netymon.com
Senior RDF/SemanticWeb Consultant
Netymon Pty Ltd