more precision fixes for unix_timestamp (#2918)

Author: jycor

enginetest/queries/script_queries.go

@@ -3068,7 +3068,7 @@ CREATE TABLE tab3 (
 			{
 				Query: "SELECT unix_timestamp(timestamp_col), unix_timestamp(datetime_col) from datetime_table",
 				Expected: []sql.Row{
-					{"86400.000000", "57600.000000"},
+					{"86400", "57600"},
 				},
 			},
 		},
@@ -5133,6 +5133,11 @@ CREATE TABLE tab3 (
 		Name:    "UNIX_TIMESTAMP function preserves trailing 0s",
 		SetUpScript: []string{
 			"SET time_zone = '+07:00';",
+			"create table dt (dt0 datetime(0), dt1 datetime(1), dt2 datetime(2), dt3 datetime(3), dt4 datetime(4), dt5 datetime(5), dt6 datetime(6));",
+			"insert into dt values ('2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456', '2020-01-02 12:34:56.123456')",
+			// TODO: time length not supported, so by default we have max precision
+			"create table t (d date, tt time);",
+			"insert into t values ('2020-01-02 12:34:56.123456', '12:34:56.123456');",
 		},
 		Assertions: []ScriptTestAssertion{
 			{
@@ -5153,6 +5158,18 @@ CREATE TABLE tab3 (
 					{"981178496.123457"},
 				},
 			},
+			{
+				Query: "select unix_timestamp(dt0), unix_timestamp(dt1), unix_timestamp(dt2), unix_timestamp(dt3), unix_timestamp(dt4), unix_timestamp(dt5), unix_timestamp(dt6) from dt;",
+				Expected: []sql.Row{
+					{"1577943296", "1577943296.1", "1577943296.12", "1577943296.123", "1577943296.1235", "1577943296.12346", "1577943296.123456"},
+				},
+			},
+			{
+				Query: "select unix_timestamp(d), unix_timestamp(tt) from t;",
+				Expected: []sql.Row{
+					{"1577898000", "1743140096.123456"},
+				},
+			},
 		},
 	},
 

sql/expression/convert.go

@@ -21,6 +21,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/dolthub/vitess/go/sqltypes"
 	"github.com/sirupsen/logrus"
 	"gopkg.in/src-d/go-errors.v1"
 
@@ -155,7 +156,7 @@ func (c *Convert) Type() sql.Type {
 	case ConvertToDate:
 		return types.Date
 	case ConvertToDatetime:
-		return types.DatetimeMaxPrecision
+		return types.MustCreateDatetimeType(sqltypes.Datetime, c.typeLength)
 	case ConvertToDecimal:
 		if c.cachedDecimalType == nil {
 			c.cachedDecimalType = createConvertedDecimalType(c.typeLength, c.typeScale, true)

sql/expression/function/date.go

@@ -405,19 +405,18 @@ var _ sql.CollationCoercible = (*UnixTimestamp)(nil)
 
 const MaxUnixTimeMicroSecs = 32536771199999999
 
-// noEval returns true if the expression contains an expression that cannot be evaluated without sql.Context or sql.Row.
-func noEval(expr sql.Expression) bool {
-	var hasBadExpr bool
+// canEval returns if the expression contains an expression that cannot be evaluated without sql.Context or sql.Row.
+func canEval(expr sql.Expression) bool {
+	evaluable := true
 	transform.InspectExpr(expr, func(e sql.Expression) bool {
 		switch e.(type) {
-		case *expression.GetField:
-			hasBadExpr = true
-		case *ConvertTz:
-			hasBadExpr = true
+		case *expression.GetField, *ConvertTz:
+			evaluable = false
+			return true
 		}
-		return hasBadExpr
+		return false
 	})
-	return hasBadExpr
+	return evaluable
 }
 
 func getNowExpr(expr sql.Expression) *Now {
@@ -436,7 +435,7 @@ func evalNowType(now *Now) sql.Type {
 	if now.prec == nil {
 		return types.Int64
 	}
-	if noEval(now.prec) {
+	if !canEval(now.prec) {
 		return types.MustCreateDecimalType(19, 6)
 	}
 	prec, pErr := now.prec.Eval(nil, nil)
@@ -463,7 +462,10 @@ func NewUnixTimestamp(args ...sql.Expression) (sql.Expression, error) {
 	}
 
 	arg := args[0]
-	if noEval(arg) {
+	if dtType, isDtType := arg.Type().(sql.DatetimeType); isDtType {
+		return &UnixTimestamp{Date: arg, typ: types.MustCreateDecimalType(19, uint8(dtType.Precision()))}, nil
+	}
+	if !canEval(arg) {
 		return &UnixTimestamp{Date: arg, typ: types.MustCreateDecimalType(19, 6)}, nil
 	}
 	if now := getNowExpr(arg); now != nil {

sql/types/datetime.go

@@ -360,7 +360,10 @@ func (t datetimeType) MustConvert(v interface{}) interface{} {
 
 // Equals implements the Type interface.
 func (t datetimeType) Equals(otherType sql.Type) bool {
-	return t.baseType == otherType.Type()
+	if dtType, isDtType := otherType.(sql.DatetimeType); isDtType {
+		return t.baseType == dtType.Type() && t.precision == dtType.Precision()
+	}
+	return false
 }
 
 // MaxTextResponseByteLength implements the Type interface