Merge pull request #3302 from dolthub/angela/nullnotexists

Wrap nullable hoisted filter in IsTrue

Author: angelamayxie

enginetest/queries/script_queries.go

@@ -13439,6 +13439,20 @@ select * from t1 except (
 			},
 		},
 	},
+	{
+		// https://github.com/dolthub/dolt/issues/10070
+		Name: "NOT EXISTS with nullable filter",
+		SetUpScript: []string{
+			"CREATE TABLE t0(c0 INT , c1 INT);",
+			"INSERT INTO t0(c0, c1) VALUES (1, -2);",
+		},
+		Assertions: []ScriptTestAssertion{
+			{
+				Query:    `SELECT * FROM t0 WHERE NOT EXISTS (SELECT 1 FROM (SELECT 1) alias0 WHERE (CASE -1 WHEN t0.c1 THEN false END));`,
+				Expected: []sql.Row{{1, -2}},
+			},
+		},
+	},
 }
 
 var SpatialScriptTests = []ScriptTest{

sql/analyzer/hoist_filters.go

@@ -131,7 +131,13 @@ func recurseSubqueryForOuterFilters(n sql.Node, a *Analyzer, corr sql.ColSet) (s
 				newCorr = newCorr.Union(outOfScope)
 				keepFilters = append(keepFilters, e)
 			} else {
-				// nothing tethers the subquery to this scope
+				// nothing tethers the subquery or filter expression to this scope
+				if sq == nil && e.IsNullable() {
+					// If a filter expression has been hoisted out of a subquery, it needs to be made not nullable. This
+					// is because filters that evaluate to null in an Exists or In subquery are treated the same as
+					// false.
+					e = expression.NewIsTrue(e)
+				}
 				hoistFilters = append(hoistFilters, e)
 			}
 		}