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[Bigdata-developers] Breakdown of mutation count statistic or way of aborting an update
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From: Jeremy J C. <jj...@sy...> - 2015-02-10 18:23:42
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This may be an enhancement suggestion to
com.bigdata.rdf.sail.webapp.BigdataRDFContext.SparqlUpdateResponseWriter.updateEvent(SPARQLUpdateEvent)
What I really want to do is:
1) make an update using a DELETE/INSERT SPARQL update query
2) make several ASK queries
3) abort 1 if the result of any of the queries in 2 was false
4) know which of the queries in 2 was false
I am generally expecting the ASK queries to all return true, and can live with inefficiencies in step 4.
I am using the NanoSPARQLServer, and want the whole operation 1 - 4 to be safe to use concurrently.
A possible fairly direct approach of meeting my use case would be to provide extensions to SPARQL update with an
ABORT IF ASK ….
(which is the negation of 3, …)
and providing more control over the SparqlUpdateResponseWriter
Using the NSS, posting a multipart SPARQL update e.g.:
=====
INSERT {
GRAPH <http://foo.bar/> {
<http://foo.bar/> <http://foo.bar/> 3 .
}
}
WHERE {} ;
DELETE {
GRAPH <http://foo.bar/>
{ ?s ?p ?o }
}
WHERE {
GRAPH <http://foo.bar/>
{ ?s ?p ?o }
FILTER ( true )
}
=====
in which the second operation undoes the first.
What I currently get back is (a variation of):
===
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html;charset=UTF-8"><title>bigdata®</title
></head
><body><pre>DeleteInsert
INSERT
QUADS {
QUADS {
StatementPatternNode(ConstantNode(TermId(1U)[http://foo.bar/]), ConstantNode(TermId(1U)[http://foo.bar/]), ConstantNode(XSDInteger(3)), ConstantNode(TermId(1U)[http://foo.bar/])) [scope=NAMED_CONTEXTS]
}
}
WHERE
JoinGroupNode {
}
</pre
><p>totalElapsed=2ms, elapsed=2ms</p
><hr><pre>DeleteInsert
DELETE
QUADS {
QUADS {
StatementPatternNode(VarNode(s), VarNode(p), VarNode(o), VarNode(g)) [scope=NAMED_CONTEXTS]
}
}
WHERE
JoinGroupNode {
JoinGroupNode [context=VarNode(g)] {
StatementPatternNode(VarNode(s), VarNode(p), VarNode(o), VarNode(g)) [scope=NAMED_CONTEXTS]
}
}
</pre
><p>totalElapsed=58ms, elapsed=52ms</p
><hr><p>COMMIT: totalElapsed=70ms, commitTime=1423585942631, mutationCount=2</p
></body
></html
>
===
Looking at the code, it would be fairly easy to also include the mutationCount after each operation.
I could then structure my code as,
DELETE INSERT ;
(reversed) DELETE INSERT IF ASK 1 ;
(reversed) DELETE INSERT IF ASK 2 ;
(reversed) DELETE INSERT IF ASK 3 ;
and then the result would tell me, by analysis of the mutation counts, if any of the ASK conditions held true.
It would also be helpful if I could switch off the bulk of the uninteresting echo in
body.node("pre").text(thisOp.toString())//
.close();
in
com.bigdata.rdf.sail.webapp.BigdataRDFContext.SparqlUpdateResponseWriter.updateEvent(SPARQLUpdateEvent)
My operations are often fairly large, and the cost of this data that I never examine is non-trivial
My best outcome, would be:
improved control over the SparqlUpdateResponseWriter
and an ABORT operation
so that my update becomes
DELETE INSERT ;
ABORT IF ASK 1 ;
ABORT IF ASK 2 ;
ABORT IF ASK 3
and the analysis of the return result is to find out which of the ABORTs fired (if any)
Jeremy
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