Re: [Exist-open] Return of the 'document id and proxy id differ' error?

[Wolfgang <wol...@ex...>]

Hi,

> I've done a little more experimenting at home with 1.2.2 and the same
> file to see if I could cause a similar crash to the one that was
> happening at work by saving a file to the eXist db with overlapping
> @xml:id attributes.  I had expected that creating a file with two
> elements and identical @xml:id attributes would crash the db when I
> queried against this attribute.  It didn't happen.

It is always possible that an error will only appear if the index is in 
a certain state and that you need to run your tests on exactly the same 
database contents.

> Could anyone confirm that eXist does not treat a file with two
> elements with identical @xml:id attributes as invalid XML file?  If
> so, we can rule that out as a cause of my db corruption.

As far as I can see without further testing, the XML parser doesn't 
complain about duplicate xml:id attributes and eXist will just store 
them as two occurrences of the same xml:id value. But I have to take a 
closer look into this issue and maybe do some stress-testing with xml:ids...

> Alternatively, could insufficient memory allocated to eXist be causing
> the problem?  I notice at home that log entries such as this appear
> after I upload my 6.7 mb file via java admin client or oXygen:

Insufficient memory is always dangerous. The effects of an out-of-memory 
error are somehow unpredictable and may lead to unnoticed corruptions. 
Java doesn't show any warnings before it runs out of memory. All you get 
is a small message on stderr.

It is thus very important to keep an eye on the memory usage of your 
applications. How much max memory did you grant to Java (-Xmx setting)? 
And what setting do you use for cacheSize in conf.xml?

Wolfgang

> p.s. Wolfgang - Thanks for your offer to examine the db.  If we decide
> that's necessary, what files exactly do you need?  The WEB-INF folder?
>  (Would it help at all just to see the 6mb file in question, or is it
> best to send the whole db?)

I will need the entire db if you cannot reproduce the error with the 6mb 
file alone, plus some instructions on how to trigger the exception.