On 12/08/13 17:56, Nicolas Torzec wrote:
With respect to the RDF export I'd advocate for:
- an RDF format with one fact per line.
- the use of a mature/proven RDF generation framework.
Optimizing too early based on a limited and/or biased view of the potential use cases may not be a good idea in the long run. I'd rather keep it simple and standard at the data publishing level, and let consumers access data easily and optimize processing to their need.
RDF has several official, standardised syntaxes, and one of them is Turtle. Using it is not a form of optimisation, just a choice of syntax. Every tool I have ever used for serious RDF work (triple stores, libraries, even OWL tools) supports any of the standard RDF syntaxes *just as well*. I do see that there are some advantages in some formats and others in others (I agree with most arguments that have been put forward). But would it not be better to first take a look at the actual content rather than debating the syntactic formatting now? As I said, this is not the final syntax anyway, which will be created with different code in a different programming language.
Also, I should not have to run a preprocessing step for filtering out the pieces of data that do not follow the standardŠ
To the best of our knowledge, there are no such pieces in the current dump. We should try to keep this conversation somewhat related to the actual Wikidata dump that is created by the current version of the Python script on github (I will also upload a dump again tomorrow; currently, you can only get the dump by running the script yourself). I know I suggested that one could parse Turtle in a robust way (which I still think one can) but I am not suggesting for a moment that this should be necessary for using Wikidata dumps in the future. I am committed to fix any error as it is found, but so far I don't get much input in that direction.
Note that I also understand the need for a format that groups every facts about an subject into one record, and serialize them one record per line. It sometime makes life easier for bulk processing of large datasets. But that's a different discussion.
As I said: advantages and disadvantages. This is why we will probably have all desired formats at some time. But someone needs to start somewhere.
Markus
-- Nicolas Torzec.
On 8/12/13 1:49 AM, "Markus Krötzsch" markus@semantic-mediawiki.org wrote:
On 11/08/13 22:29, Tom Morris wrote:
On Sat, Aug 10, 2013 at 2:30 PM, Markus Krötzsch <markus@semantic-mediawiki.org mailto:markus@semantic-mediawiki.org> wrote:
Anyway, if you restrict yourself to tools that are installed by default on your system, then it will be difficult to do many interesting things with a 4.5G RDF file ;-) Seriously, the RDF dump is really meant specifically for tools that take RDF inputs. It is not very straightforward to encode all of Wikidata in triples, and it leads to some inconvenient constructions (especially a lot of reification). If you don't actually want to use an RDF tool and you are just interested in the data, then there would be easier ways of getting it.A single fact per line seems like a pretty convenient format to me. What format do you recommend that's easier to process?
I'd suggest some custom format that at least keeps single data values in one line. For example, in RDF, you have to do two joins to find all items that have a property with a date in the year 2010. Even with a line-by-line format, you will not be able to grep this. So I think a less normalised representation would be nicer for direct text-based processing. For text-based processing, I would probably prefer a format where one statement is encoded on one line. But it really depends on what you want to do. Maybe you could also remove some data to obtain something that is easier to process.
Markus
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