Replace Time.Sub call in TIMESTAMPDIFF with microsecondsDiff

enginetest/queries/function_queries.go

@@ -990,47 +990,33 @@ var FunctionQueryTests = []QueryTest{
 		Query:    "select timestampdiff(quarter, '0000-01-01', '9999-12-31 23:59:59.999999');",
 		Expected: []sql.Row{{39999}},
 	},
+	// TIMESTAMPDIFF tests for large timestamp differences // https://github.com/dolthub/dolt/issues/10397
+	// 0000-03-01 is used here instead of 0000-01-01 because 0000 is a leap year in Go (ie 0000-02-29 is a valid date),
+	// but not in MySQL. As a result, date differences between any day before 0000-02-29 and any after are off by one
+	// day.
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(microsecond, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{315569433599999999}},
+		Query:    "select timestampdiff(microsecond, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{315564335999999999}},
 	},
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(second, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{315569433599}},
+		Query:    "select timestampdiff(second, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{315564335999}},
 	},
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(minute, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{5259490559}},
+		Query:    "select timestampdiff(minute, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{5259405599}},
 	},
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(hour, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{87658175}},
+		Query:    "select timestampdiff(hour, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{87656759}},
 	},
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(day, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{3652423}},
+		Query:    "select timestampdiff(day, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{3652364}},
 	},
 	{
-		// https://github.com/dolthub/dolt/issues/10397
-		Skip: true,
-		// might need to change first date to 0001-01-01 since 0000 is a leap year in Go but not in MySQL
-		Query:    "select timestampdiff(week, '0000-01-01', '9999-12-31 23:59:59.999999');",
-		Expected: []sql.Row{{521774}},
+		Query:    "select timestampdiff(week, '0000-03-01', '9999-12-31 23:59:59.999999');",
+		Expected: []sql.Row{{521766}},
 	},
 	// TRIM Function Tests
 	{

sql/expression/function/time_math.go

@@ -672,28 +672,26 @@ func (t *TimestampDiff) Eval(ctx *sql.Context, row sql.Row) (interface{}, error)
 	time1 := expr1.(time.Time)
 	time2 := expr2.(time.Time)
 
-	diff := time2.Sub(time1)
-
 	var res int64
 	switch unit {
 	case "microsecond":
-		res = diff.Microseconds()
+		res = microsecondsDiff(time1, time2)
 	case "second":
-		res = int64(diff.Seconds())
+		res = microsecondsDiff(time1, time2) / sql.MicrosecondsPerSecond
 	case "minute":
-		res = int64(diff.Minutes())
+		res = microsecondsDiff(time1, time2) / sql.MicrosecondsPerMinute
 	case "hour":
-		res = int64(diff.Hours())
+		res = microsecondsDiff(time1, time2) / sql.MicrosecondsPerHour
 	case "day":
-		res = int64(diff.Hours() / 24)
+		res = microsecondsDiff(time1, time2) / sql.MicrosecondsPerDay
 	case "week":
-		res = int64(diff.Hours() / (24 * 7))
+		res = microsecondsDiff(time1, time2) / sql.MicrosecondsPerWeek
 	case "month":
 		res = monthsDiff(time1, time2)
 	case "quarter":
-		res = monthsDiff(time1, time2) / 3
+		res = monthsDiff(time1, time2) / sql.MonthsPerQuarter
 	case "year":
-		res = monthsDiff(time1, time2) / 12
+		res = monthsDiff(time1, time2) / sql.MonthsPerYear
 	default:
 		return nil, errors.NewKind("invalid interval unit: %s").New(unit)
 	}
@@ -723,13 +721,18 @@ func monthsDiff(time1, time2 time.Time) int64 {
 	} else if beforeDay == afterDay {
 		beforeHour, beforeMin, beforeSec := before.Clock()
 		afterHour, afterMin, afterSec := after.Clock()
-		secondDiff := (afterHour-beforeHour)*3600 + (afterMin-beforeMin)*60 + (afterSec - beforeSec)
+		secondDiff := int64(afterHour-beforeHour)*sql.SecondsPerHour + int64(afterMin-beforeMin)*sql.SecondsPerMinute +
+			int64(afterSec-beforeSec)
 		if secondDiff < 0 {
 			monthDiff -= 1
 		} else if secondDiff == 0 && before.Nanosecond() > after.Nanosecond() {
 			monthDiff -= 1
 		}
 	}
 
-	return int64(sign) * (int64(yearDiff*12) + monthDiff)
+	return int64(sign) * (int64(yearDiff*sql.MonthsPerYear) + monthDiff)
+}
+
+func microsecondsDiff(date1, date2 time.Time) int64 {
+	return date2.UnixMicro() - date1.UnixMicro()
 }

sql/time.go

@@ -23,6 +23,29 @@ import (
 	"time"
 )
 
+const (
+	NanosecondsPerMicrosecond = int64(time.Microsecond)
+
+	MicrosecondsPerSecond = int64(time.Second / time.Microsecond)
+
+	SecondsPerMinute      = int64(time.Second / time.Minute)
+	MicrosecondsPerMinute = int64(time.Minute / time.Microsecond)
+
+	SecondsPerHour      = int64(time.Hour / time.Second)
+	MicrosecondsPerHour = int64(time.Hour / time.Microsecond)
+
+	hoursPerDay        = 24
+	DayDuration        = hoursPerDay * time.Hour
+	MicrosecondsPerDay = MicrosecondsPerHour * hoursPerDay
+
+	daysPerWeek         = 7
+	MicrosecondsPerWeek = MicrosecondsPerDay * daysPerWeek
+
+	MonthsPerQuarter = 3
+
+	MonthsPerYear = 12
+)
+
 // offsetRegex is a regex for matching MySQL offsets (e.g. +01:00).
 var offsetRegex = regexp.MustCompile(`(?m)^([+\-])(\d{1,2}):(\d{2})$`)