Re: [dotNetRDF-bugs] Bugs, problems, ideas, questions

[Rob V. <rv...@do...>]

Hi Alexander

Thanks for reporting the bugs and contributing your ideas.

1 - I have fixed this as suggested as of revision 625

2 - The UpdateGraph is intended primarily for use internally by the API, it 
happens to be a public method since it's an interface method.  It's 
designed to combine the two operations since from an IO point of view there 
operations are typically achieved via the same mechanism.  It's intended 
use is for persisting changes to Graphs as they happen, if you are making a 
fixed number/predetermined changes to a Graph then it's typically best to 
load it using the LoadGraph() method, change it then persist it back to the 
store using the SaveGraph() method.

3 - I have altered the implementation of the UpdateGraph method in all 
existing IGenericIOManager implementations so they accept null arguments 
for either list as of revision 625

4 - UpdateGraph uses lists since as I said wrt point 2 it's designed 
primarily for internal usage.  Where it's used internally we're buffering 
triples that are to be added/removed in lists and then persisting them in a 
bulk operation for efficiency purposes.  I may add an additional overload 
in the future which accepts IEnumerable<Triple> but I don't really see the 
need.

With the example you gave why not just use the SaveGraph() method instead - 
I assume you're adding to an existing Graph and want to preserve what's 
already in the Graph in Virtuoso?

Creating a list doesn't really have that much overhead associated with it, 
typically the triples are stored in a dictionary/hash table anyway.  
Converting an enumerable to a list doesn't actually use that much memory 
since you aren't physically copying the triples you're only creating copies 
of the references to the triples (total overhead roughly 2/4 bytes per 
triple - depends on whether you're running 32/64 bit system)

5 - Fix is applied as of revision 625 - the fix is still slightly 
unsatisfactory since what if the query is something like ASK WHERE {?select 
?p ?o} that will be flagged as a select query when it is not.

6 - I will get back to you about licensing, I have another similar question 
from another user and I need to look into compatibility of different 
licenses before I can answer your question.  Is there any particular reason 
why you don't like the GPL?

Rob Vesse

----------------------------------------
From: "Alexander Sidorov" <ale...@gm...>
Sent: Saturday, February 20, 2010 8:57 PM
To: dot...@li...
Subject: [dotNetRDF-bugs] Bugs, problems, ideas, questions 

Hello!

1. VirtuosoManager.LoadNode method doesn't work correctly 
with queries that contain OPTIONAL clause. Such queries return DbNull 
for result sets at which optional variables are not set. I have just 
added one more "else if" and it works nice:

            else if (n is DBNull)
            {
                
temp = null;
            }
2. Why not to split UpdateGraph method 
to AddToGraph and RemoveFromGraph methods? I think it would be more 
convenient for most usecases.

3. Method UpdateGraph (at least in VirtuosoManager) throws exception
 when removals variable is null. That's why I have to pass empty list to
 make my addition-only UpdateGraph call work. I think it would be nice 
to make this query work with additions or/and removals equal to null.

4. Why does method UpdateGraph has List<Triple> but not 
IEnumerable<Triple> parameters? It is inconvenient, for example, 
when I would like to save graph's triples:

            Graph 
graph = new Graph();

            RdfXmlParser parser = new RdfXmlParser();
            
parser.Load(graph, fileName);

            this._virtuosoManager.UpdateGraph(graphUri,
 graph.Triples.ToList(), new List<VDS.RDF.Triple>());

I have to create the list and it makes my code less efficient 
(imagine big graph).

5. VirtuosoManager.Query method contains the
 following code:

                else if (results.Rows.Count == 1
 && results.Columns.Count == 1)

                {
                    //Single Row and Column implies
 ASK/DESCRIBE/CONSTRUCT results

I have some SELECT-queries that 
return one variable and sometimes one result. And because of the 
previous code my results are lost (because I expect my variable, but not
 variable called Result. I think it would be nice to make simple check 
(just search ask, describe or construct words in the query) to determine
 is this SELECT-query or not.

6. Is there any way to get dotnetRDF library (only library) 
without any GPL dependencies under BSD or similar license?

That's
 all for today :)

Regards,
Alexander