evalengine: fix numeric coercibility

go/sqltypes/type.go

@@ -136,7 +136,7 @@ func IsNull(t querypb.Type) bool {
 // switch statements for those who want to cover types
 // by their category.
 const (
-	Unknown    = -1
+	Unknown    = querypb.Type(-1)
 	Null       = querypb.Type_NULL_TYPE
 	Int8       = querypb.Type_INT8
 	Uint8      = querypb.Type_UINT8

go/test/endtoend/vtgate/queries/random/random_test.go

@@ -339,4 +339,5 @@ func TestBuggyQueries(t *testing.T) {
 	mcmp.Exec("select count(tbl1.dname) as caggr1 from dept as tbl0 left join dept as tbl1 on tbl1.dname > tbl1.loc where tbl1.loc <=> tbl1.dname group by tbl1.dname order by tbl1.dname asc")
 	mcmp.Exec("select count(*) from (select count(*) from dept as tbl0) as tbl0")
 	mcmp.Exec("select count(*), count(*) from (select count(*) from dept as tbl0) as tbl0, dept as tbl1")
+	mcmp.Exec(`select distinct case max(tbl0.ename) when min(tbl0.job) then 'sole' else count(case when false then -27 when 'gazelle' then tbl0.deptno end) end as caggr0 from emp as tbl0`)
 }

go/vt/vtgate/engine/opcode/constants.go

@@ -139,13 +139,19 @@ func (code AggregateOpcode) Type(typ querypb.Type) querypb.Type {
 	case AggregateUnassigned:
 		return sqltypes.Null
 	case AggregateGroupConcat:
+		if typ == sqltypes.Unknown {
+			return sqltypes.Unknown
+		}
 		if sqltypes.IsBinary(typ) {
 			return sqltypes.Blob
 		}
 		return sqltypes.Text
 	case AggregateMax, AggregateMin, AggregateAnyValue:
 		return typ
 	case AggregateSumDistinct, AggregateSum:
+		if typ == sqltypes.Unknown {
+			return sqltypes.Unknown
+		}
 		if sqltypes.IsIntegral(typ) || sqltypes.IsDecimal(typ) {
 			return sqltypes.Decimal
 		}

go/vt/vtgate/evalengine/api_literal.go

@@ -223,7 +223,7 @@ func NewColumn(offset int, typ Type, original sqlparser.Expr) *Column {
 	return &Column{
 		Offset:            offset,
 		Type:              typ.Type,
-		Collation:         defaultCoercionCollation(typ.Coll),
+		Collation:         typedCoercionCollation(typ.Type, typ.Coll),
 		Original:          original,
 		dynamicTypeOffset: -1,
 	}

go/vt/vtgate/evalengine/collation.go

@@ -16,12 +16,115 @@ limitations under the License.
 
 package evalengine
 
-import "vitess.io/vitess/go/mysql/collations"
+import (
+	"vitess.io/vitess/go/mysql/collations"
+	"vitess.io/vitess/go/mysql/collations/colldata"
+	"vitess.io/vitess/go/sqltypes"
+)
 
-func defaultCoercionCollation(id collations.ID) collations.TypedCollation {
-	return collations.TypedCollation{
-		Collation:    id,
-		Coercibility: collations.CoerceCoercible,
-		Repertoire:   collations.RepertoireUnicode,
+func typedCoercionCollation(typ sqltypes.Type, id collations.ID) collations.TypedCollation {
+	switch {
+	case sqltypes.IsNull(typ):
+		return collationNull
+	case sqltypes.IsNumber(typ) || sqltypes.IsDateOrTime(typ):
+		return collationNumeric
+	case typ == sqltypes.TypeJSON:
+		return collationJSON
+	default:
+		return collations.TypedCollation{
+			Collation:    id,
+			Coercibility: collations.CoerceCoercible,
+			Repertoire:   collations.RepertoireUnicode,
+		}
 	}
 }
+
+func evalCollation(e eval) collations.TypedCollation {
+	switch e := e.(type) {
+	case nil:
+		return collationNull
+	case evalNumeric, *evalTemporal:
+		return collationNumeric
+	case *evalJSON:
+		return collationJSON
+	case *evalBytes:
+		return e.col
+	default:
+		return collationBinary
+	}
+}
+
+func mergeCollations(c1, c2 collations.TypedCollation, t1, t2 sqltypes.Type) (collations.TypedCollation, colldata.Coercion, colldata.Coercion, error) {
+	if c1.Collation == c2.Collation {
+		return c1, nil, nil, nil
+	}
+
+	lt := sqltypes.IsText(t1) || sqltypes.IsBinary(t1)
+	rt := sqltypes.IsText(t2) || sqltypes.IsBinary(t2)
+	if !lt || !rt {
+		if lt {
+			return c1, nil, nil, nil
+		}
+		if rt {
+			return c2, nil, nil, nil
+		}
+		return collationBinary, nil, nil, nil
+	}
+
+	env := collations.Local()
+	return colldata.Merge(env, c1, c2, colldata.CoercionOptions{
+		ConvertToSuperset:   true,
+		ConvertWithCoercion: true,
+	})
+}
+
+func mergeAndCoerceCollations(left, right eval) (eval, eval, collations.TypedCollation, error) {
+	lt := left.SQLType()
+	rt := right.SQLType()
+
+	mc, coerceLeft, coerceRight, err := mergeCollations(evalCollation(left), evalCollation(right), lt, rt)
+	if err != nil {
+		return nil, nil, collations.TypedCollation{}, err
+	}
+	if coerceLeft == nil && coerceRight == nil {
+		return left, right, mc, nil
+	}
+
+	left1 := newEvalRaw(lt, left.(*evalBytes).bytes, mc)
+	right1 := newEvalRaw(rt, right.(*evalBytes).bytes, mc)
+
+	if coerceLeft != nil {
+		left1.bytes, err = coerceLeft(nil, left1.bytes)
+		if err != nil {
+			return nil, nil, collations.TypedCollation{}, err
+		}
+	}
+	if coerceRight != nil {
+		right1.bytes, err = coerceRight(nil, right1.bytes)
+		if err != nil {
+			return nil, nil, collations.TypedCollation{}, err
+		}
+	}
+	return left1, right1, mc, nil
+}
+
+type collationAggregation struct {
+	cur collations.TypedCollation
+}
+
+func (ca *collationAggregation) add(env *collations.Environment, tc collations.TypedCollation) error {
+	if ca.cur.Collation == collations.Unknown {
+		ca.cur = tc
+	} else {
+		var err error
+		ca.cur, _, _, err = colldata.Merge(env, ca.cur, tc, colldata.CoercionOptions{ConvertToSuperset: true, ConvertWithCoercion: true})
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (ca *collationAggregation) result() collations.TypedCollation {
+	return ca.cur
+}

go/vt/vtgate/evalengine/compiler_asm.go

@@ -4165,13 +4165,13 @@ func (asm *assembler) Fn_DATEADD_D(unit datetime.IntervalType, sub bool) {
 		}
 
 		tmp := env.vm.stack[env.vm.sp-2].(*evalTemporal)
-		env.vm.stack[env.vm.sp-2] = tmp.addInterval(interval, collations.TypedCollation{}, env.now)
+		env.vm.stack[env.vm.sp-2] = tmp.addInterval(interval, collations.Unknown, env.now)
 		env.vm.sp--
 		return 1
 	}, "FN DATEADD TEMPORAL(SP-2), INTERVAL(SP-1)")
 }
 
-func (asm *assembler) Fn_DATEADD_s(unit datetime.IntervalType, sub bool, col collations.TypedCollation) {
+func (asm *assembler) Fn_DATEADD_s(unit datetime.IntervalType, sub bool, col collations.ID) {
 	asm.adjustStack(-1)
 	asm.emit(func(env *ExpressionEnv) int {
 		var interval *datetime.Interval

go/vt/vtgate/evalengine/compiler_test.go

@@ -164,6 +164,7 @@ func TestCompilerSingle(t *testing.T) {
 		expression string
 		values     []sqltypes.Value
 		result     string
+		collation  collations.ID
 	}{
 		{
 			expression: "1 + column0",
@@ -489,6 +490,12 @@ func TestCompilerSingle(t *testing.T) {
 			expression: `'2020-01-01' + interval month(date_sub(FROM_UNIXTIME(1234), interval 1 month))-1 month`,
 			result:     `CHAR("2020-12-01")`,
 		},
+		{
+			expression: `case column0 when 1 then column1 else column2 end`,
+			values:     []sqltypes.Value{sqltypes.NewInt64(42), sqltypes.NewVarChar("sole"), sqltypes.NewInt64(0)},
+			result:     `VARCHAR("0")`,
+			collation:  collations.CollationUtf8mb4ID,
+		},
 	}
 
 	tz, _ := time.LoadLocation("Europe/Madrid")
@@ -524,6 +531,9 @@ func TestCompilerSingle(t *testing.T) {
 			if expected.String() != tc.result {
 				t.Fatalf("bad evaluation from eval engine: got %s, want %s", expected.String(), tc.result)
 			}
+			if tc.collation != collations.Unknown && tc.collation != expected.Collation() {
+				t.Fatalf("bad collation evaluation from eval engine: got %d, want %d", expected.Collation(), tc.collation)
+			}
 
 			// re-run the same evaluation multiple times to ensure results are always consistent
 			for i := 0; i < 8; i++ {
@@ -535,6 +545,9 @@ func TestCompilerSingle(t *testing.T) {
 				if res.String() != tc.result {
 					t.Errorf("bad evaluation from compiler: got %s, want %s (iteration %d)", res, tc.result, i)
 				}
+				if tc.collation != collations.Unknown && tc.collation != res.Collation() {
+					t.Fatalf("bad collation evaluation from compiler: got %d, want %d", res.Collation(), tc.collation)
+				}
 			}
 		})
 	}

go/vt/vtgate/evalengine/eval.go

@@ -238,7 +238,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 			fval, _ := fastparse.ParseFloat64(v.RawStr())
 			return newEvalFloat(fval), nil
 		default:
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
@@ -265,7 +265,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 			fval, _ := fastparse.ParseFloat64(v.RawStr())
 			dec = decimal.NewFromFloat(fval)
 		default:
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
@@ -285,7 +285,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 			i, err := fastparse.ParseInt64(v.RawStr(), 10)
 			return newEvalInt64(i), err
 		default:
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
@@ -304,7 +304,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 			u, err := fastparse.ParseUint64(v.RawStr(), 10)
 			return newEvalUint64(u), err
 		default:
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
@@ -315,15 +315,15 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 	case sqltypes.IsText(typ) || sqltypes.IsBinary(typ):
 		switch {
 		case v.IsText() || v.IsBinary():
-			return newEvalRaw(v.Type(), v.Raw(), defaultCoercionCollation(collation)), nil
+			return newEvalRaw(v.Type(), v.Raw(), typedCoercionCollation(v.Type(), collation)), nil
 		case sqltypes.IsText(typ):
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
 			return evalToVarchar(e, collation, true)
 		default:
-			e, err := valueToEval(v, defaultCoercionCollation(collation))
+			e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 			if err != nil {
 				return nil, err
 			}
@@ -333,7 +333,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 	case typ == sqltypes.TypeJSON:
 		return json.NewFromSQL(v)
 	case typ == sqltypes.Date:
-		e, err := valueToEval(v, defaultCoercionCollation(collation))
+		e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 		if err != nil {
 			return nil, err
 		}
@@ -344,7 +344,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 		}
 		return d, nil
 	case typ == sqltypes.Datetime || typ == sqltypes.Timestamp:
-		e, err := valueToEval(v, defaultCoercionCollation(collation))
+		e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 		if err != nil {
 			return nil, err
 		}
@@ -355,7 +355,7 @@ func valueToEvalCast(v sqltypes.Value, typ sqltypes.Type, collation collations.I
 		}
 		return dt, nil
 	case typ == sqltypes.Time:
-		e, err := valueToEval(v, defaultCoercionCollation(collation))
+		e, err := valueToEval(v, typedCoercionCollation(v.Type(), collation))
 		if err != nil {
 			return nil, err
 		}

go/vt/vtgate/evalengine/eval_temporal.go

@@ -140,7 +140,7 @@ func (e *evalTemporal) isZero() bool {
 	return e.dt.IsZero()
 }
 
-func (e *evalTemporal) addInterval(interval *datetime.Interval, strcoll collations.TypedCollation, now time.Time) eval {
+func (e *evalTemporal) addInterval(interval *datetime.Interval, coll collations.ID, now time.Time) eval {
 	var tmp *evalTemporal
 	var ok bool
 
@@ -150,16 +150,16 @@ func (e *evalTemporal) addInterval(interval *datetime.Interval, strcoll collatio
 		tmp.dt.Date, ok = e.dt.Date.AddInterval(interval)
 	case tt == sqltypes.Time && !interval.Unit().HasDateParts():
 		tmp = &evalTemporal{t: e.t}
-		tmp.dt.Time, tmp.prec, ok = e.dt.Time.AddInterval(interval, strcoll.Valid())
+		tmp.dt.Time, tmp.prec, ok = e.dt.Time.AddInterval(interval, coll != collations.Unknown)
 	case tt == sqltypes.Datetime || tt == sqltypes.Timestamp || (tt == sqltypes.Date && interval.Unit().HasTimeParts()) || (tt == sqltypes.Time && interval.Unit().HasDateParts()):
 		tmp = e.toDateTime(int(e.prec), now)
-		tmp.dt, tmp.prec, ok = e.dt.AddInterval(interval, strcoll.Valid())
+		tmp.dt, tmp.prec, ok = e.dt.AddInterval(interval, coll != collations.Unknown)
 	}
 	if !ok {
 		return nil
 	}
-	if strcoll.Valid() {
-		return newEvalRaw(sqltypes.Char, tmp.ToRawBytes(), strcoll)
+	if coll != collations.Unknown {
+		return newEvalRaw(sqltypes.Char, tmp.ToRawBytes(), typedCoercionCollation(sqltypes.Char, coll))
 	}
 	return tmp
 }

go/vt/vtgate/evalengine/expr_bvar.go

@@ -70,7 +70,7 @@ func (bv *BindVariable) eval(env *ExpressionEnv) (eval, error) {
 
 		tuple := make([]eval, 0, len(bvar.Values))
 		for _, value := range bvar.Values {
-			e, err := valueToEval(sqltypes.MakeTrusted(value.Type, value.Value), defaultCoercionCollation(collations.CollationForType(value.Type, bv.Collation)))
+			e, err := valueToEval(sqltypes.MakeTrusted(value.Type, value.Value), typedCoercionCollation(value.Type, collations.CollationForType(value.Type, bv.Collation)))
 			if err != nil {
 				return nil, err
 			}
@@ -86,7 +86,7 @@ func (bv *BindVariable) eval(env *ExpressionEnv) (eval, error) {
 		if bv.typed() {
 			typ = bv.Type
 		}
-		return valueToEval(sqltypes.MakeTrusted(typ, bvar.Value), defaultCoercionCollation(collations.CollationForType(typ, bv.Collation)))
+		return valueToEval(sqltypes.MakeTrusted(typ, bvar.Value), typedCoercionCollation(typ, collations.CollationForType(typ, bv.Collation)))
 	}
 }
 
@@ -110,7 +110,7 @@ func (bv *BindVariable) typeof(env *ExpressionEnv) (ctype, error) {
 	case sqltypes.BitNum:
 		return ctype{Type: sqltypes.VarBinary, Flag: flagBit, Col: collationNumeric}, nil
 	default:
-		return ctype{Type: tt, Flag: 0, Col: defaultCoercionCollation(collations.CollationForType(tt, bv.Collation))}, nil
+		return ctype{Type: tt, Flag: 0, Col: typedCoercionCollation(tt, collations.CollationForType(tt, bv.Collation))}, nil
 	}
 }
 
@@ -119,7 +119,7 @@ func (bvar *BindVariable) compile(c *compiler) (ctype, error) {
 
 	if bvar.typed() {
 		typ.Type = bvar.Type
-		typ.Col = defaultCoercionCollation(collations.CollationForType(bvar.Type, bvar.Collation))
+		typ.Col = typedCoercionCollation(bvar.Type, collations.CollationForType(bvar.Type, bvar.Collation))
 	} else if c.dynamicTypes != nil {
 		typ = c.dynamicTypes[bvar.dynamicTypeOffset]
 	} else {