dweiss commented on PR #16307:
URL: https://github.com/apache/lucene/pull/16307#issuecomment-4905822682
LLM says this, sorry I can't offer more help.
```
The mechanism
The DV drill‑down goes SortedNumericDocValuesRangeQuery → (no skipper)
DocValuesValueRangeIterator, a two‑phase iterator whose matches() must confirm
that a value is in range. For
dense ranges the bulk scorer is DenseConjunctionBulkScorer. In scoreWindow
(DenseConjunctionBulkScorer.java:193‑208) it buckets clauses:
int docIdRunEnd = w.docIDRunEnd();
if (w.docID() > min || docIdRunEnd < minRunEndThreshold) {
windowClauses.add(w); // needs per-doc matches() confirmation
} else {
minDocIDRunEnd = Math.min(minDocIDRunEnd, docIdRunEnd); // treated as
FULLY MATCHING
}
...
if (acceptDocs == null && windowClauses.isEmpty()) {
collector.collectRange(min, minDocIDRunEnd); // collect WITHOUT
calling matches()
For a width‑1 window (max == min+1, i.e. a partition boundary),
minRunEndThreshold = min(min+2048, max) = min+1. The clause sits at w.docID()
== min, so:
- Before #16307: docIDRunEnd() == min < min+1 → goes to windowClauses →
matches() is confirmed. Correct.
- After #16307: docIDRunEnd() == min+1 >= min+1 → goes to the "fully
matching" bucket → collectRange(min, min+1) collects the boundary doc without
confirming matches().
That boundary doc has the field (so the approximation is positioned on it)
but its value may be out of range — it gets counted anyway → the ±1. The
default docIDRunEnd()
optimistically assumes the current (unconfirmed) doc matches, which is
fine for ReqExclBulkScorer (which calls it only after matches()), but
DenseConjunctionBulkScorer consults it
before confirmation.
```
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