MB-53298 Do not return error for MISSING value in join processing

Previous code for join assumes that the inner of a join should have
a valid value, since the join is being processed after a potential
match has been found. However, in this bug, we are doing the
equivalent of a cartesian join, and an explicit MISSING value is
used on the inner side of a join. This triggers a sanity check
failure.

The fix is to allow such MISSING value to proceed with join
processing. Also optimizer hints processing is fixed when joining
on expression/subquery terms.

Change-Id: I2ce8ee1759dc1547451241cfa6f19102d089639b
Reviewed-on: https://review.couchbase.org/c/query/+/178581
Reviewed-by: Sitaram Vemulapalli <sitaram.vemulapalli@couchbase.com>
Tested-by: Bingjie Miao <bingjie.miao@couchbase.com>

execution/join_nl.go

@@ -10,7 +10,6 @@ package execution
 
 import (
 	"encoding/json"
-	"fmt"
 
 	"github.com/couchbase/query/errors"
 	"github.com/couchbase/query/expression"
@@ -202,15 +201,12 @@ func processAnsiExec(item value.AnnotatedValue, right_item value.AnnotatedValue,
 	for _, alias := range aliases {
 		val, ok := right_item.Field(alias)
 		if !ok {
-			if len(aliases) > 1 {
-				// in case of HASH JOIN, when there are multiple aliases on the
-				// build side, value could be MISSING for an alias, if right_item
-				// contains the result of an outer join
-				continue
-			} else {
-				context.Error(errors.NewExecutionInternalError(fmt.Sprintf("processAnsiExec: annotated value not found for %s", alias)))
-				return false, false, nil
-			}
+			// it's possible to have a MISSING value for an alias, e.g.,
+			// in case of HASH JOIN, when there are multiple aliases on the
+			// build side, value could be MISSING for an alias, if right_item
+			// contains the result of an outer join;
+			// or if a MISSING value is specified explicitly in an expression term
+			continue
 		}
 
 		joined.SetField(alias, val)

planner/build_join_ansi.go

@@ -393,13 +393,28 @@ func (this *builder) buildAnsiJoinOp(node *algebra.AnsiJoin) (op plan.Operator,
 					return hjoin, err
 				}
 			}
+		} else {
+			if preferHash {
+				if inferJoinHint {
+					leftBaseKeyspace.MarkHashUnavailable()
+				} else {
+					baseKeyspace.MarkHashUnavailable()
+				}
+			}
 		}
 
 		scans, newOnclause, cost, cardinality, size, frCost, err := this.buildAnsiJoinSimpleFromTerm(right, node.Onclause(), node.Outer(), "join")
 		if err != nil {
 			return nil, err
 		}
 
+		if preferHash && !joinEnum {
+			if inferJoinHint {
+				leftBaseKeyspace.SetJoinHintError()
+			} else {
+				baseKeyspace.SetJoinHintError()
+			}
+		}
 		if newOnclause != nil {
 			node.SetOnclause(newOnclause)
 		}
@@ -697,13 +712,28 @@ func (this *builder) buildAnsiNestOp(node *algebra.AnsiNest) (op plan.Operator,
 					return hnest, err
 				}
 			}
+		} else {
+			if preferHash {
+				if inferJoinHint {
+					leftBaseKeyspace.MarkHashUnavailable()
+				} else {
+					baseKeyspace.MarkHashUnavailable()
+				}
+			}
 		}
 
 		scans, newOnclause, cost, cardinality, size, frCost, err := this.buildAnsiJoinSimpleFromTerm(right, node.Onclause(), node.Outer(), "nest")
 		if err != nil {
 			return nil, err
 		}
 
+		if preferHash && !joinEnum {
+			if inferJoinHint {
+				leftBaseKeyspace.SetJoinHintError()
+			} else {
+				baseKeyspace.SetJoinHintError()
+			}
+		}
 		if newOnclause != nil {
 			node.SetOnclause(newOnclause)
 		}

test/gsi/test_cases/ansijoin/case_ansijoin_bugs.json

@@ -234,6 +234,50 @@
                 "c11": 4
             }
 	]
+    },
+    {
+        "testcase": "MB-53298, part 1",
+        "explain": {
+            "disabled": false,
+            "results": [
+                {
+                    "present": true
+                }
+            ],
+            "statement": "SELECT true AS present FROM $explan AS p WHERE ANY v WITHIN p.plan.`~children` SATISFIES v.`#operator` = 'HashJoin' AND v.`outer` = true END"
+        },
+        "statements":"SELECT x, y FROM [1, 2] AS x LEFT JOIN [1, MISSING] AS y ON x = y",
+        "results": [
+            {
+                "x": 1,
+                "y": 1
+            },
+            {
+                "x": 2
+            }
+	]
+    },
+    {
+        "testcase": "MB-53298, part 2",
+        "explain": {
+            "disabled": false,
+            "results": [
+                {
+                    "present": true
+                }
+            ],
+            "statement": "SELECT true AS present FROM $explan AS p WHERE ANY v WITHIN p.plan.`~children` SATISFIES v.`#operator` = 'NestedLoopJoin' AND v.`outer` = true END"
+        },
+        "statements":"SELECT x, y FROM [1, 2] AS x LEFT JOIN [1, MISSING] AS y USE HASH(PROBE) ON x = y",
+        "results": [
+            {
+                "x": 1,
+                "y": 1
+            },
+            {
+                "x": 2
+            }
+	]
     }
 ]