fix safe context assertion in DoltgresType.Compare

Author: elianddb

server/types/type.go

@@ -217,7 +217,12 @@ func (t *DoltgresType) Compare(ctx context.Context, v1 interface{}, v2 interface
 
 	if t.TypType == TypeType_Enum {
 		// TODO: temporary solution to getting the enum type (which has label info) into the 'enum_cmp' function
-		qf := globalFunctionRegistry.GetFunction(ctx.(*sql.Context), t.CompareFunc)
+		// ctx is not guaranteed to be a *sql.Context when called from index comparator goroutines.
+		sqlCtx, ok := ctx.(*sql.Context)
+		if !ok {
+			sqlCtx = sql.NewEmptyContext()
+		}
+		qf := globalFunctionRegistry.GetFunction(sqlCtx, t.CompareFunc)
 		resTypes := qf.ResolvedTypes()
 		newFunc := qf.WithResolvedTypes([]*DoltgresType{t, t, resTypes[len(resTypes)-1]})
 		i, err := newFunc.(QuickFunction).CallVariadic(nil, v1, v2)
@@ -226,7 +231,12 @@ func (t *DoltgresType) Compare(ctx context.Context, v1 interface{}, v2 interface
 		}
 		return int(i.(int32)), nil
 	} else if t == Oidvector {
-		i, err := globalFunctionRegistry.GetFunction(ctx.(*sql.Context), t.CompareFunc).CallVariadic(nil, v1, v2)
+		// ctx is not guaranteed to be a *sql.Context when called from index comparator goroutines.
+		sqlCtx, ok := ctx.(*sql.Context)
+		if !ok {
+			sqlCtx = sql.NewEmptyContext()
+		}
+		i, err := globalFunctionRegistry.GetFunction(sqlCtx, t.CompareFunc).CallVariadic(nil, v1, v2)
 		if err != nil {
 			return 0, err
 		}

testing/go/types_test.go

@@ -3789,6 +3789,27 @@ var enumTypeTests = []ScriptTest{
 			},
 		},
 	},
+	{
+		Name: "btree index scan on enum column returns correct rows",
+		SetUpScript: []string{
+			`CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple')`,
+			`CREATE TABLE enumtest (col rainbow)`,
+			`INSERT INTO enumtest VALUES ('red'), ('orange'), ('yellow'), ('green')`,
+			`CREATE UNIQUE INDEX enumtest_btree ON enumtest USING btree (col)`,
+			// Force the planner to use the btree index rather than a sequential scan.
+			`SET enable_seqscan = off`,
+			`SET enable_bitmapscan = off`,
+		},
+		Assertions: []ScriptTestAssertion{
+			{Query: `SELECT * FROM enumtest WHERE col = 'orange'`, Expected: []sql.Row{{"orange"}}},
+			{
+				Query: `SELECT * FROM enumtest WHERE col > 'orange' ORDER BY col`,
+				// Enum values sort by their position in the type definition, not alphabetically.
+				Expected: []sql.Row{{"yellow"}, {"green"}},
+			},
+			{Query: `SELECT * FROM enumtest WHERE col < 'orange' ORDER BY col`, Expected: []sql.Row{{"red"}}},
+		},
+	},
 	{
 		Skip: true,
 		Name: "create type with existing array type name updates the name of the array type",