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From John Vines <john.w.vi...@ugov.gov>
Subject Re: Question about special characters in row key
Date Mon, 23 Apr 2012 14:45:16 GMT
Sounds like your software isn't setting end keys. If you create a range
with just a start, it will go on ad infinitum until you no longer iterate.
This is similar to doing a scan using -b without -e.

As for why you can't replicate it in your normal scan, it could either be
the key not being what you think it is, or just a problem with the way
shell handles non alphanumeric characters. One option would be to truncate
your scan's start to "Journal 1 and see what you hit first. If you see
yourself starting way beyond your "Journal 1 (1940... then we may not be
handling quotes well in the shell or your key is not right. At this point,
try substituting \x22 for the quotation mark and scanning again.

If that still doesn't work, then you may want to dig through your middle
projects ingest process to see how it's forming the keys for you.

John

On Mon, Apr 23, 2012 at 10:20 AM, Steven Troxell
<steven.troxell@gmail.com>wrote:

> Hi everyone,
>
> I'm attempting to use a beta project designed to integrate an RDF engine
> with Accumulo.  There seems to be a bug somewhere in the code that fails to
> correctly query accumulo that results in failing to limit the results to
> the following sparql query:
>
> SELECT ?yr
> WHERE {
>   ?journal rdf:type bench:Journal .
>   ?journal dc:title "Journal 1 (1940)"^^xsd:string .
>   ?journal dcterms:issued ?yr
> }
>
> I get results back ranging from 1940-1966, while the Hbase integration
> with this particular software correctly just returns 1940.  It's fairly
> complicated to explain the entire process of how accumulo scans are spawned
> from the above query, but I believe I've narrowed down a possible source of
> error that I'd like further leads:
>
>
> I suspect the developers may not be handling the  quotations correctly in
> scanning accumulo.  I say this because this is a sample row from the
> accumulo shell:
>
> "Journal 1 (1940)"^^http://www.w3.org/2001/XMLSchema#string o:
> http://localhost/publications/journals/Journal1/1940
> http://purl.org/dc/elements/1.1/title [ROLE1]
>
> From the shell, I have yet to figure out how to successfully scan for the
> row key,  just a straight scan -b "Journal 1 (1940)"^^
> http://www.w3.org/2001/XMLSchema#string fails to usage,  wrapping the
> rowkey in single quotes seems to return all results, which is what I
> suspect happening in the actual software I'm using, as it explains the
> behavior I'm seeing.
>
> I'm guessing, but not entirely sure, the developers may have misused the
> programatic scans as well on account of not handling the quotations
> correctly?  Is this reasonable, and can anyone provide further insight?
>
> Thanks,
> Steve
>

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