gszadovszky commented on code in PR #1328:
URL: https://github.com/apache/parquet-java/pull/1328#discussion_r1624573384
##########
parquet-column/src/main/java/org/apache/parquet/internal/column/columnindex/IndexIterator.java:
##########
@@ -55,6 +55,111 @@ static PrimitiveIterator.OfInt rangeTranslate(int from, int
to, IntUnaryOperator
return new IndexIterator(from, to + 1, i -> true, translator);
}
+ static PrimitiveIterator.OfInt intersection(PrimitiveIterator.OfInt lhs,
PrimitiveIterator.OfInt rhs) {
+ return new PrimitiveIterator.OfInt() {
+ private int next = fetchNext();
+
+ @Override
+ public int nextInt() {
+ if (!hasNext()) {
+ throw new NoSuchElementException();
+ }
+ int result = next;
+ next = fetchNext();
+ return result;
+ }
+
+ @Override
+ public boolean hasNext() {
+ return next != -1;
+ }
+
+ private int fetchNext() {
+ if (!lhs.hasNext() || !rhs.hasNext()) {
+ return -1;
+ }
+
+ // Since we know both iterators are in sorted order, we can iterate
linearly through until
+ // we find the next value that belongs to both iterators, or terminate
if none exist
+ int nextL = lhs.next();
+ int nextR = rhs.next();
+ while (nextL < nextR && lhs.hasNext()) {
+ nextL = lhs.next();
+ }
+ if (nextL == nextR) {
+ return nextL;
+ }
+ while (nextR < nextL && rhs.hasNext()) {
+ nextR = rhs.next();
+ }
+ if (nextL == nextR) {
+ return nextL;
+ }
Review Comment:
It seems that an outer loop is missing that would run till the end of the
shorter iterator. Example:
```
lhs: 1, 3, 5, 7
rhs: 2, 4, 6, 7
```
After these lines at the first invocation of the method `nextL` will be `3`
and `nextR` will be `4` and `-1` is about the be returned while `7` is a common
element in both.
(It also means that the unit test for this one is not complete...)
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