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Posted to pr@jena.apache.org by GitBox <gi...@apache.org> on 2022/11/15 13:25:45 UTC
[GitHub] [jena] SimonBin commented on a diff in pull request #1616: improve jena performance and behaviour in certain path cases
SimonBin commented on code in PR #1616:
URL: https://github.com/apache/jena/pull/1616#discussion_r1022784175
##########
jena-arq/src/main/java/org/apache/jena/sparql/algebra/optimize/TransformPathFlattern.java:
##########
@@ -53,9 +58,60 @@ public TransformPathFlattern(PathCompiler pathCompiler)
@Override
public Op transform(OpPath opPath)
{
- // Flatten down to triples where possible.
- PathBlock pattern = pathCompiler.reduce(opPath.getTriplePath()) ;
- // Any generated paths of exactly one to triple; convert to Op.
- return PathLib.pathToTriples(pattern) ;
+ Op op = transformReduce(opPath, pathCompiler);
+ return op;
}
-}
+
+ static Op transformReduce(Op op, PathCompiler pathCompiler) {
+ return Transformer.transform(
+ new TransformCopy() {
+ @Override
+ public Op transform(OpPath opPath) {
+ // Flatten down to triples where possible.
+ PathBlock pattern = pathCompiler.reduce(opPath.getTriplePath());
+ // Any generated paths of exactly one to triple; convert to Op.
+ Op op = PathLib.pathToTriples(pattern);
+ return transformAlt(op, pathCompiler);
+ }
+ },
+ op);
+ }
+
+ static Op transformAlt(Op op, PathCompiler pathCompiler) {
+ return Transformer.transform(new AltTransformer(pathCompiler), op);
+ }
+
+ private static class AltTransformer extends TransformCopy {
+ private PathCompiler pathCompiler;
+
+ public AltTransformer(PathCompiler pathCompiler) {
+ this.pathCompiler = pathCompiler;
+ }
+
+ @Override
+ public Op transform(OpPath opPath) {
+ TriplePath triplePath = opPath.getTriplePath();
+ Path path = triplePath.getPath();
+ if (path instanceof P_Alt) {
+ Node s = triplePath.getSubject();
Review Comment:
Thank you for the thorough analysis and concern. In my testing, I got the expected results when querying e.g. ` { ?s ex:foo _:bnode . _:bnode (ex:a | ex:b) ?o }` as you suggested. Do you have any additional pointers how to verify the safety of the transform?
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