Aklakan commented on code in PR #2925:
URL: https://github.com/apache/jena/pull/2925#discussion_r1916869473
##########
jena-arq/src/main/java/org/apache/jena/sparql/engine/iterator/QueryIterLateral.java:
##########
@@ -292,17 +295,33 @@ public Op transform(OpTable opTable) {
// By the assignment restriction, the binding only needs to be
added to each row of the table.
Table table = opTable.getTable();
// Table vars.
- List<Var> vars = new ArrayList<>(table.getVars());
- binding.vars().forEachRemaining(vars::add);
- TableN table2 = new TableN(vars);
+ List<Var> tableVars = table.getVars();
+ List<Var> vars = new ArrayList<>(tableVars);
+
+ // Track variables that appear both in the table and the binding.
+ List<Var> commonVars = new ArrayList<>();
+
+ // Index variables in a set if there are more than a few of them.
+ Collection<Var> tableVarsIndex = tableVars.size() > 4 ? new
HashSet<>(tableVars) : tableVars;
+ binding.vars().forEachRemaining(v -> {
+ if (tableVarsIndex.contains(v)) {
+ commonVars.add(v);
+ } else {
+ vars.add(v);
+ }
+ });
+
+ List<Binding> bindings = new ArrayList<>(table.size());
BindingBuilder builder = BindingFactory.builder();
table.iterator(null).forEachRemaining(row->{
- builder.reset();
- builder.addAll(row);
- builder.addAll(binding);
- table2.addBinding(builder.build());
+ if (Algebra.compatible(row, binding, commonVars.iterator())) {
Review Comment:
There is potentially another can of worms I was about to open w.r.t. sep7:
Perhaps its worthy of opening an issue and discussion on sparql-dev. The
reason I added the compatibility check was because I had the following query in
mind, which for reasons I do not yet understand is currently prohibited:
```sparql
SELECT * { VALUES ?department {
<urn:dept1>
<urn:dept2>
}
LATERAL { SELECT * { VALUES (?department ?employee) {
( <urn:dept1> <urn:person1> )
( <urn:dept1> <urn:person2> )
( <urn:dept2> <urn:person1> )
}
} ORDER BY ?employee LIMIT 1
}
}
```
| department | employee |
|--------------------|---------|
| <urn:dept1> | <urn:person1> |
| <urn:dept2> | <urn:person1> |
-------------------------------
So when creating the PR I was surprised to find out that this query is
already considered illegal.
Removing the restrictions `SyntaxVarScope.checkLATERAL` on `Element_Bind`
and `Element_Data`) and adding the check for compatible bindings (as done in
the PR) naturally makes the query work.
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: pr-unsubscr...@jena.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: pr-unsubscr...@jena.apache.org
For additional commands, e-mail: pr-h...@jena.apache.org
