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bug(query): or/or-join deduplication silently missed identical bindings (fixed in 4c8270d, needs test) #82
Description
Summary
Commit 4c8270d (merged without a PR or issue) fixed a silent correctness bug in apply_or_clauses in src/query/datalog/executor.rs.
The bug
or and or-join deduplication used BTreeSet<Vec<(String, Value)>> to track seen bindings. The key was constructed as:
let key: Vec<_> = b.iter().map(|(k, v)| (k.clone(), v.clone())).collect();
seen.insert(key);b is a HashMap<String, Value>. HashMap::iter() returns entries in non-deterministic order. Two bindings that are logically identical (same key-value pairs) can produce different Vec orderings on different iterations, causing BTreeSet::insert to treat them as distinct and failing to deduplicate. The result: duplicate result rows in queries using or or or-join.
The fix (already applied)
4c8270d added key.sort_unstable() before seen.insert(key), normalising the key order so identical bindings always produce the same vector and deduplicate correctly.
What's still missing
A regression test. The fix was applied without a test that would catch a regression. A future refactor could accidentally revert the sort.
Suggested test
Add an integration test in tests/disjunction_test.rs (or a new tests/or_dedup_test.rs):
#[test]
fn or_does_not_return_duplicate_bindings() {
// Setup: entity has both :tag-a true and :tag-b true.
// Query: (query [:find ?e :where (or [?e :tag-a true] [?e :tag-b true])])
// Expected: exactly one result row for ?e, not two.
let db = Minigraf::open_in_memory().unwrap();
db.execute(r#"(transact [[:db/add "e1" :tag-a true]
[:db/add "e1" :tag-b true]])"#).unwrap();
let results = db.execute(
r#"(query [:find ?e :where (or [?e :tag-a true] [?e :tag-b true])])"#
).unwrap();
assert_eq!(results.len(), 1, "entity matching both branches must appear exactly once");
}Do NOT use {:?} format on Result or any type containing Uuid in assert messages (CLAUDE.md testing conventions).
Files
src/query/datalog/executor.rs—apply_or_clauses(lines ~1190–1255)tests/disjunction_test.rs— add the regression test
Activity
test: add regression test for issue #82 (or/or-join deduplication)
test: add regression test for issue #82 (or/or-join deduplication) (#88)