[CALCITE-3498] Unnest operation's ordinality should be deterministic

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.21.0
• Fix Version/s: 1.22.0
• Component/s: core
• Labels: pull-request-available

Environment

**

• Assignee: Feng Zhu
• Reporter: Feng Zhu
• Created: 13/Nov/19 11:45
• Updated: 06/Mar/20 04:36
• Resolved: 15/Nov/19 08:17

Description

Current now, the compution of unnest operation's ordinality is conducted in current() method ( https://github.com/apache/calcite/blob/3853118b4d1d48f7d3970b5488baf7ca78d5028e/core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java#L2764).

Consequently, when the method is called, the ordinality will be incremented, leading to incorrect and un-deterministic result.

We can use a simple query for illustration.

Query:
==============================================================
select v, o
from unnest(array[100,200]) with ordinality as t1(v, o)
where v > 1

Expected Result
==============================================================
V=100; O=1
V=200; O=2

However, we get the follow incorrect result.

V=100; O=2
V=200; O=4

We can infer to the code generated. It can be seen that inputEnumerator.current() has been called two times, one for filter (v>1) and one for select (v, o).

public org.apache.calcite.linq4j.Enumerable bind(final org.apache.calcite.DataContext root) {
  final org.apache.calcite.linq4j.Enumerable _inputEnumerable = ..............
  final org.apache.calcite.linq4j.Enumerable _inputEnumerable0 = child.selectMany(org.apache.calcite.runtime.SqlFunctions.flatProduct(new int[] {
    -1}, true, new org.apache.calcite.runtime.SqlFunctions.FlatProductInputType[] {
    org.apache.calcite.runtime.SqlFunctions.FlatProductInputType.SCALAR}));
  return new org.apache.calcite.linq4j.AbstractEnumerable(){
      public org.apache.calcite.linq4j.Enumerator enumerator() {
        return new org.apache.calcite.linq4j.Enumerator(){
            public final org.apache.calcite.linq4j.Enumerator inputEnumerator = _inputEnumerable0.enumerator();
            public void reset() {
              inputEnumerator.reset();
            }            public boolean moveNext() {
              while (inputEnumerator.moveNext()) {
                if (org.apache.calcite.runtime.SqlFunctions.toInt(((org.apache.calcite.runtime.FlatLists.ComparableList) inputEnumerator.current()).get(0)) > 1) {
                  return true;
                }
              }
              return false;
            }            public void close() {
              inputEnumerator.close();
            }            public Object current() {
              final org.apache.calcite.runtime.FlatLists.ComparableList current = (org.apache.calcite.runtime.FlatLists.ComparableList) inputEnumerator.current();
              return new Object[] {
                  current.get(0),
                  current.get(1)};
            }          };
      }    };
}
public Class getElementType() {
  return java.lang.Object[].class;
}

Issue Links

• links to: GitHub Pull Request #1575