amaliujia commented on a change in pull request #1503: [CALCITE-3408] Add
support for enumerable intersect/minus all
URL: https://github.com/apache/calcite/pull/1503#discussion_r335120242
##########
File path:
linq4j/src/main/java/org/apache/calcite/linq4j/EnumerableDefaults.java
##########
@@ -532,15 +533,19 @@ public void remove() {
* by Enumerable.)
*/
public static <TSource> Enumerable<TSource> except(
- Enumerable<TSource> source0, Enumerable<TSource> source1) {
+ Enumerable<TSource> source0, Enumerable<TSource> source1, boolean all) {
Set<TSource> set = new HashSet<>();
- source0.into(set);
- try (Enumerator<TSource> os = source1.enumerator()) {
+ Collection<TSource> resultCollection = all ? HashMultiset.create() : new
HashSet<>();
Review comment:
Thank Yanlin.
I was looking for some preciously definition of the set op "ALL"
implementation (like comments).
Basically either something like:
```
// Say for Row R, there are m instances on left and n instances on right,
// INTERSECT ALL outputs MIN(m, n) instances of R.
```
Or
```
Calcite implementation follows XX DB's implementation. See their doc(link)
```
If there is no such thing I will just read code.
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