HanumathRao commented on code in PR #3480:
URL: https://github.com/apache/calcite/pull/3480#discussion_r1370589771
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core/src/test/java/org/apache/calcite/test/enumerable/EnumerableRepeatUnionTest.java:
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@@ -45,6 +45,17 @@
*/
class EnumerableRepeatUnionTest {
+ @Test void testGenerateNumbersUsingSql() {
+ CalciteAssert.that()
+ .query("WITH RECURSIVE delta(n) AS (\n"
+ + " VALUES (1)\n"
+ + " UNION ALL\n"
Review Comment:
@mihaibudiu Thanks for reviewing the changes. I agree with @rubenada
regarding the explanation as to why this use case doesn't run into infinite
growth. I believe in general that semantics of UNION / UNION ALL are subtle in
Recursive queries.
Here is an example (again from postgresql) where usage of the union all
(http://sqlfiddle.com/#!17/9eecb/111278) will run into infinite loop but usage
of union works fine.
The infinite loop for the above example actually is because of the result
set being a multi set when union all is used.
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