Fix time zone shifts when the shift happens on a time zone boundary

When a time zone shift happened at the edge of a time bucket, the logic
was incorrect. When we added an hour to the day with a time grouping of
2 hours, we took the hour away from the previous bucket instead of the
next bucket so the first bucket of the day would be from midnight to 1
AM and the second bucket would include 1 AM to 4 AM (2 AM to 3 AM does
not exist when shifting forwards). The correct buckets should have been
12 AM to 2 AM for the first bucket of the day and 3 AM to 4 AM for the
second (since 2 AM to 3 AM does not exist).

This also modifies the tests to use table tests and sub tests.

CHANGELOG.md

@@ -22,6 +22,7 @@
 - [#8569](https://github.com/influxdata/influxdb/issues/8569): Fix the cq start and end times to use unix timestamps.
 - [#8601](https://github.com/influxdata/influxdb/pull/8601): Fixed time boundaries for continuous queries with time zones.
 - [#8097](https://github.com/influxdata/influxdb/pull/8097): Return query parsing errors in CSV formats.
+- [#8607](https://github.com/influxdata/influxdb/issues/8607): Fix time zone shifts when the shift happens on a time zone boundary.
 
 ## v1.3.1 [unreleased]
 

influxql/iterator.gen.go

@@ -726,7 +726,7 @@ func (itr *floatFillIterator) Next() (*FloatPoint, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff
@@ -4073,7 +4073,7 @@ func (itr *integerFillIterator) Next() (*IntegerPoint, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff
@@ -7403,7 +7403,7 @@ func (itr *unsignedFillIterator) Next() (*UnsignedPoint, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff
@@ -10733,7 +10733,7 @@ func (itr *stringFillIterator) Next() (*StringPoint, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff
@@ -14063,7 +14063,7 @@ func (itr *booleanFillIterator) Next() (*BooleanPoint, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff

influxql/iterator.gen.go.tmpl

@@ -727,7 +727,7 @@ func (itr *{{$k.name}}FillIterator) Next() (*{{$k.Name}}Point, error) {
 	// Check to see if we have passed over an offset change and adjust the time
 	// to account for this new offset.
 	if itr.opt.Location != nil {
-		if _, offset := itr.opt.Zone(itr.window.time); offset != itr.window.offset {
+		if _, offset := itr.opt.Zone(itr.window.time - 1); offset != itr.window.offset {
 			diff := itr.window.offset - offset
 			if abs(diff) < int64(itr.opt.Interval.Duration) {
 				itr.window.time += diff

influxql/iterator.go

@@ -849,14 +849,13 @@ func (opt IteratorOptions) Window(t int64) (start, end int64) {
 	t -= int64(opt.Interval.Offset)
 
 	// Retrieve the zone offset for the start time.
-	var startOffset int64
+	var zone int64
 	if opt.Location != nil {
-		_, startOffset = opt.Zone(t)
-		t += startOffset
+		_, zone = opt.Zone(t)
 	}
 
 	// Truncate time by duration.
-	dt := t % int64(opt.Interval.Duration)
+	dt := (t + zone) % int64(opt.Interval.Duration)
 	if dt < 0 {
 		// Negative modulo rounds up instead of down, so offset
 		// with the duration.
@@ -874,38 +873,48 @@ func (opt IteratorOptions) Window(t int64) (start, end int64) {
 	// after the offset switch. Now that we are at midnight in UTC, we can
 	// lookup the zone offset again to get the real starting offset.
 	if opt.Location != nil {
-		_, adjustedOffset := opt.Zone(start)
+		_, startOffset := opt.Zone(start)
 		// Do not adjust the offset if the offset change is greater than or
 		// equal to the duration.
-		if o := startOffset - adjustedOffset; o != 0 && abs(o) < int64(opt.Interval.Duration) {
-			startOffset = adjustedOffset
+		if o := zone - startOffset; o != 0 && abs(o) < int64(opt.Interval.Duration) {
+			start += o
 		}
 	}
-	start += int64(opt.Interval.Offset) - startOffset
+	start += int64(opt.Interval.Offset)
 
 	// Find the end time.
 	if dt := int64(opt.Interval.Duration) - dt; MaxTime-dt <= t {
 		end = MaxTime
 	} else {
 		end = t + dt
 	}
-	end += int64(opt.Interval.Offset) - startOffset
 
 	// Retrieve the zone offset for the end time.
 	if opt.Location != nil {
 		_, endOffset := opt.Zone(end)
 		// Adjust the end time if the offset is different from the start offset.
-		if startOffset != endOffset {
-			offset := startOffset - endOffset
-
-			// Only apply the offset if it is smaller than the duration.
-			// This prevents going back in time and creating time windows
-			// that don't make any sense.
-			if abs(offset) < int64(opt.Interval.Duration) {
-				end += offset
+		// Only apply the offset if it is smaller than the duration.
+		// This prevents going back in time and creating time windows
+		// that don't make any sense.
+		if o := zone - endOffset; o != 0 && abs(o) < int64(opt.Interval.Duration) {
+			// If the offset is greater than 0, that means we are adding time.
+			// Added time goes into the previous interval because the clocks
+			// move backwards. If the offset is less than 0, then we are skipping
+			// time. Skipped time comes after the switch so if we have a time
+			// interval that lands on the switch, it comes from the next
+			// interval and not the current one. For this reason, we need to know
+			// when the actual switch happens by seeing if the time switch is within
+			// the current interval. We calculate the zone offset with the offset
+			// and see if the value is the same. If it is, we apply the
+			// offset.
+			if o > 0 {
+				end += o
+			} else if _, z := opt.Zone(end + o); z == endOffset {
+				end += o
 			}
 		}
 	}
+	end += int64(opt.Interval.Offset)
 	return
 }