[Timestamp] Use microsecond precision to support full range of BigQuery timestamps

internal/decoder.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"math/big"
 	"strconv"
+	"time"
 
 	"github.com/goccy/go-json"
 )
@@ -73,11 +74,14 @@ func decodeFromValueLayout(layout *ValueLayout) (Value, error) {
 		}
 		return TimeValue(t), nil
 	case TimestampValueType:
-		unixnano, err := strconv.ParseInt(layout.Body, 10, 64)
+		microsec, err := strconv.ParseInt(layout.Body, 10, 64)
+		microSecondsInSecond := int64(time.Second) / int64(time.Microsecond)
+		sec := microsec / microSecondsInSecond
+		remainder := microsec - (sec * microSecondsInSecond)
 		if err != nil {
-			return nil, fmt.Errorf("failed to parse unixnano for timestamp value %s: %w", layout.Body, err)
+			return nil, fmt.Errorf("failed to parse unixmicro for timestamp value %s: %w", layout.Body, err)
 		}
-		return TimestampValue(timeFromUnixNano(unixnano)), nil
+		return TimestampValue(time.Unix(sec, remainder*int64(time.Microsecond))), nil
 	case IntervalValueType:
 		return parseInterval(layout.Body)
 	case JsonValueType:

internal/encoder.go

@@ -162,12 +162,11 @@ func ValueFromZetaSQLValue(v types.Value) (Value, error) {
 	case types.TIME:
 		return timeValueFromLiteral(v.ToPacked64TimeMicros())
 	case types.TIMESTAMP:
-		nanosec, err := v.ToUnixNanos()
-		if err != nil {
-			return nil, err
-		}
-		sec := nanosec / int64(time.Second)
-		return timestampValueFromLiteral(time.Unix(sec, nanosec-sec*int64(time.Second)))
+		microsec := v.ToUnixMicros()
+		microSecondsInSecond := int64(time.Second) / int64(time.Microsecond)
+		sec := microsec / microSecondsInSecond
+		remainder := microsec - (sec * microSecondsInSecond)
+		return timestampValueFromLiteral(time.Unix(sec, remainder*int64(time.Microsecond)))
 	case types.NUMERIC, types.BIG_NUMERIC:
 		return numericValueFromLiteral(v.SQLLiteral(0))
 	case types.INTERVAL:
@@ -659,7 +658,7 @@ func valueLayoutFromValue(v Value) (*ValueLayout, error) {
 	case TimestampValue:
 		return &ValueLayout{
 			Header: TimestampValueType,
-			Body:   fmt.Sprint(time.Time(vv).UnixNano()),
+			Body:   fmt.Sprint(time.Time(vv).UnixMicro()),
 		}, nil
 	case *IntervalValue:
 		s, err := vv.ToString()

query_test.go

@@ -3981,6 +3981,16 @@ SELECT date, EXTRACT(ISOYEAR FROM date), EXTRACT(YEAR FROM date), EXTRACT(MONTH
 				{createTimestampFormatFromTime(now.UTC())},
 			},
 		},
+		{
+			name:  "minimum / maximum timestamp value uses microsecond precision and range",
+			query: `SELECT TIMESTAMP '0001-01-01 00:00:00.000000+00', TIMESTAMP '9999-12-31 23:59:59.999999+00'`,
+			expectedRows: [][]interface{}{
+				{
+					createTimestampFormatFromTime(time.Date(1, 1, 1, 0, 0, 0, 0, time.UTC)),
+					createTimestampFormatFromTime(time.Date(9999, 12, 31, 23, 59, 59, 999999000, time.UTC)),
+				},
+			},
+		},
 		{
 			name:         "string",
 			query:        `SELECT STRING(TIMESTAMP "2008-12-25 15:30:00+00", "UTC")`,