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app/vmselect/promql: properly handle duplicate series when merging cached results with the results obtained from the database

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evalRollupFuncNoCache() may return time series with identical labels (aka duplicate series)
when performing queries satisfying all the following conditions:

- It must select time series with multiple metric names. For example, {__name__=~"foo|bar"}
- The series selector must be wrapped into rollup function, which drops metric names. For example, rate({__name__=~"foo|bar"})
- The rollup function must be wrapped into aggregate function, which has no streaming optimization.
  For example, quantile(0.9, rate({__name__=~"foo|bar"})

In this case VictoriaMetrics shouldn't return `cannot merge series: duplicate series found` error.
Instead, it should fall back to query execution with disabled cache.

Also properly store the merged results. Previously they were incorrectly stored because of a typo
introduced in the commit 41a0fdaf39

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5332
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5337
This commit is contained in:
Aliaksandr Valialkin 2023-11-16 15:52:38 +01:00
parent d389a4fcf3
commit 2cbdb1db22
No known key found for this signature in database
GPG key ID: A72BEC6CD3D0DED1
4 changed files with 225 additions and 83 deletions
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50
app/vmselect/promql/eval.go
View file

@ -875,7 +875,7 @@ func evalRollupFuncWithoutAt(qt *querytracer.Tracer, ec *EvalConfig, funcName st
}
}
if funcName == "absent_over_time" {
rvs = aggregateAbsentOverTime(ec, re.Expr, rvs)
rvs = aggregateAbsentOverTime(ecNew, re.Expr, rvs)
}
if offset != 0 && len(rvs) > 0 {
// Make a copy of timestamps, since they may be used in other values.
@ -1596,8 +1596,23 @@ func evalRollupFuncWithMetricExpr(qt *querytracer.Tracer, ec *EvalConfig, funcNa
}
return rvs, nil
}
pointsPerSeries := 1 + (ec.End-ec.Start)/ec.Step
evalWithConfig := func(ec *EvalConfig) ([]*timeseries, error) {
tss, err := evalRollupFuncNoCache(qt, ec, funcName, rf, expr, me, iafc, window, pointsPerSeries)
if err != nil {
err = &UserReadableError{
Err: err,
}
return nil, err
}
return tss, nil
}
if !ec.mayCache() {
qt.Printf("do not fetch series from cache, since it is disabled in the current context")
return evalWithConfig(ec)
}
// Search for partial results in cache.
// Search for cached results.
tssCached, start := rollupResultCacheV.GetSeries(qt, ec, expr, window)
ec.QueryStats.addSeriesFetched(len(tssCached))
if start > ec.End {
@ -1613,23 +1628,28 @@ func evalRollupFuncWithMetricExpr(qt *querytracer.Tracer, ec *EvalConfig, funcNa
rollupResultCacheMiss.Inc()
}
ecCopy := copyEvalConfig(ec)
ecCopy.Start = start
pointsPerSeries := 1 + (ec.End-ec.Start)/ec.Step
tss, err := evalRollupFuncNoCache(qt, ecCopy, funcName, rf, expr, me, iafc, window, pointsPerSeries)
// Fetch missing results, which aren't cached yet.
ecNew := ec
if start != ec.Start {
ecNew = copyEvalConfig(ec)
ecNew.Start = start
}
tss, err := evalWithConfig(ecNew)
if err != nil {
err = &UserReadableError{
Err: err,
}
return nil, err
}
rvs, err := mergeTimeseries(qt, tssCached, tss, start, ec)
if err != nil {
return nil, fmt.Errorf("cannot merge series: %w", err)
}
if tss != nil {
rollupResultCacheV.PutSeries(qt, ec, expr, window, tss)
// Merge cached results with the fetched additional results.
rvs, ok := mergeSeries(qt, tssCached, tss, start, ec)
if !ok {
// Cannot merge series - fall back to non-cached querying.
qt.Printf("fall back to non-caching querying")
rvs, err = evalWithConfig(ec)
if err != nil {
return nil, err
}
}
rollupResultCacheV.PutSeries(qt, ec, expr, window, rvs)
return rvs, nil
}

153
app/vmselect/promql/rollup_result_cache.go
View file

@ -273,10 +273,6 @@ func (rrc *rollupResultCache) GetSeries(qt *querytracer.Tracer, ec *EvalConfig,
qt = qt.NewChild("rollup cache get series: query=%s, timeRange=%s, window=%d, step=%d", query, ec.timeRangeString(), window, ec.Step)
defer qt.Done()
}
if !ec.mayCache() {
qt.Printf("do not fetch series from cache, since it is disabled in the current context")
return nil, ec.Start
}
// Obtain tss from the cache.
bb := bbPool.Get()
@ -358,13 +354,25 @@ func (rrc *rollupResultCache) PutSeries(qt *querytracer.Tracer, ec *EvalConfig,
qt = qt.NewChild("rollup cache put series: query=%s, timeRange=%s, step=%d, window=%d, series=%d", query, ec.timeRangeString(), ec.Step, window, len(tss))
defer qt.Done()
}
if !ec.mayCache() {
qt.Printf("do not store series to cache, since it is disabled in the current context")
if len(tss) == 0 {
qt.Printf("do not cache empty series list")
return
}
if len(tss) == 0 {
qt.Printf("do not store empty series list")
return
if len(tss) > 1 {
// Verify whether tss contains series with duplicate naming.
// There is little sense in storing such series in the cache, since they cannot be merged in mergeSeries() later.
bb := bbPool.Get()
m := make(map[string]struct{}, len(tss))
for _, ts := range tss {
bb.B = marshalMetricNameSorted(bb.B[:0], &ts.MetricName)
if _, ok := m[string(bb.B)]; ok {
qt.Printf("do not cache series with duplicate naming %s", &ts.MetricName)
return
}
m[string(bb.B)] = struct{}{}
}
bbPool.Put(bb)
}
// Remove values up to currentTime - step - cacheTimestampOffset,
@ -523,7 +531,7 @@ func mustSaveRollupResultCacheKeyPrefix(path string) {
var tooBigRollupResults = metrics.NewCounter("vm_too_big_rollup_results_total")
// Increment this value every time the format of the cache changes.
const rollupResultCacheVersion = 10
const rollupResultCacheVersion = 11
const (
rollupResultCacheTypeSeries = 0
@ -564,74 +572,115 @@ func marshalTagFiltersForRollupResultCacheKey(dst []byte, etfs [][]storage.TagFi
return dst
}
// mergeTimeseries concatenates b with a and returns the result.
func equalTimestamps(a, b []int64) bool {
if len(a) != len(b) {
return false
}
for i, tsA := range a {
tsB := b[i]
if tsA != tsB {
return false
}
}
return true
}
// mergeSeries concatenates a with b and returns the result.
//
// true is returned on successful concatenation, false otherwise.
//
// Preconditions:
// - a mustn't intersect with b by timestamps.
// - a timestamps must be smaller than b timestamps.
// - bStart must be in the range [ec.Start .. ec.End]
// - a must contain series with all the samples on the range [ec.Start ... bStart - ec.Step] with ec.Step interval between them
// - b must contain series with all the samples on the range [bStart .. ec.End] with ec.Step interval between them
//
// Postconditions:
// - the returned series contain all the samples on the range [ec.Start .. ec.End] with ec.Step interval between them
// - a and b cannot be used after returning from the call.
func mergeTimeseries(qt *querytracer.Tracer, a, b []*timeseries, bStart int64, ec *EvalConfig) ([]*timeseries, error) {
qt = qt.NewChild("merge series len(a)=%d, len(b)=%d", len(a), len(b))
defer qt.Done()
func mergeSeries(qt *querytracer.Tracer, a, b []*timeseries, bStart int64, ec *EvalConfig) ([]*timeseries, bool) {
if qt.Enabled() {
qt = qt.NewChild("merge series on time range %s with step=%dms; len(a)=%d, len(b)=%d, bStart=%s",
ec.timeRangeString(), ec.Step, len(a), len(b), storage.TimestampToHumanReadableFormat(bStart))
defer qt.Done()
}
sharedTimestamps := ec.getSharedTimestamps()
if bStart == ec.Start {
// Nothing to merge - b covers all the time range.
// Verify b is correct.
i := 0
for i < len(sharedTimestamps) && sharedTimestamps[i] < bStart {
i++
}
aTimestamps := sharedTimestamps[:i]
bTimestamps := sharedTimestamps[i:]
if len(bTimestamps) == len(sharedTimestamps) {
// Nothing to merge - just return b to the caller
for _, tsB := range b {
if !equalTimestamps(tsB.Timestamps, bTimestamps) {
logger.Panicf("BUG: invalid timestamps in b series %s; got %d; want %d", &tsB.MetricName, tsB.Timestamps, bTimestamps)
}
tsB.denyReuse = true
tsB.Timestamps = sharedTimestamps
if len(tsB.Values) != len(tsB.Timestamps) {
logger.Panicf("BUG: unexpected number of values in b; got %d; want %d", len(tsB.Values), len(tsB.Timestamps))
}
}
return b, nil
return b, true
}
m := make(map[string]*timeseries, len(a))
bb := bbPool.Get()
defer bbPool.Put(bb)
mA := make(map[string]*timeseries, len(a))
for _, ts := range a {
bb.B = marshalMetricNameSorted(bb.B[:0], &ts.MetricName)
if _, ok := m[string(bb.B)]; ok {
return nil, fmt.Errorf("duplicate series found: %s", &ts.MetricName)
if !equalTimestamps(ts.Timestamps, aTimestamps) {
logger.Panicf("BUG: invalid timestamps in a series %s; got %d; want %d", &ts.MetricName, ts.Timestamps, aTimestamps)
}
m[string(bb.B)] = ts
bb.B = marshalMetricNameSorted(bb.B[:0], &ts.MetricName)
if _, ok := mA[string(bb.B)]; ok {
qt.Printf("cannot merge series because a series contain duplicate %s", &ts.MetricName)
return nil, false
}
mA[string(bb.B)] = ts
}
mB := make(map[string]struct{}, len(b))
rvs := make([]*timeseries, 0, len(a))
var aNaNs []float64
for _, tsB := range b {
if !equalTimestamps(tsB.Timestamps, bTimestamps) {
logger.Panicf("BUG: invalid timestamps for b series %s; got %d; want %d", &tsB.MetricName, tsB.Timestamps, bTimestamps)
}
bb.B = marshalMetricNameSorted(bb.B[:0], &tsB.MetricName)
if _, ok := mB[string(bb.B)]; ok {
qt.Printf("cannot merge series because b series contain duplicate %s", &tsB.MetricName)
return nil, false
}
mB[string(bb.B)] = struct{}{}
var tmp timeseries
tmp.denyReuse = true
tmp.Timestamps = sharedTimestamps
tmp.Values = make([]float64, 0, len(tmp.Timestamps))
tmp.MetricName.MoveFrom(&tsB.MetricName)
bb.B = marshalMetricNameSorted(bb.B[:0], &tmp.MetricName)
k := string(bb.B)
tsA := m[k]
tsA := mA[string(bb.B)]
if tsA == nil {
tStart := ec.Start
for tStart < bStart {
tmp.Values = append(tmp.Values, nan)
tStart += ec.Step
if aNaNs == nil {
tStart := ec.Start
for tStart < bStart {
aNaNs = append(aNaNs, nan)
tStart += ec.Step
}
}
tmp.Values = append(tmp.Values, aNaNs...)
} else {
tmp.Values = append(tmp.Values, tsA.Values...)
delete(m, k)
delete(mA, string(bb.B))
}
tmp.Values = append(tmp.Values, tsB.Values...)
if len(tmp.Values) != len(tmp.Timestamps) {
logger.Panicf("BUG: unexpected values after merging new values; got %d; want %d; len(a.Values)=%d; len(b.Values)=%d",
len(tmp.Values), len(tmp.Timestamps), len(tsA.Values), len(tsB.Values))
}
rvs = append(rvs, &tmp)
}
// Copy the remaining timeseries from m.
for _, tsA := range m {
// Copy the remaining timeseries from mA.
var bNaNs []float64
for _, tsA := range mA {
var tmp timeseries
tmp.denyReuse = true
tmp.Timestamps = sharedTimestamps
@ -639,18 +688,18 @@ func mergeTimeseries(qt *querytracer.Tracer, a, b []*timeseries, bStart int64, e
tmp.MetricName.MoveFrom(&tsA.MetricName)
tmp.Values = append(tmp.Values, tsA.Values...)
tStart := bStart
for tStart <= ec.End {
tmp.Values = append(tmp.Values, nan)
tStart += ec.Step
}
if len(tmp.Values) != len(tmp.Timestamps) {
logger.Panicf("BUG: unexpected values in the result after adding cached values; got %d; want %d", len(tmp.Values), len(tmp.Timestamps))
if bNaNs == nil {
tStart := bStart
for tStart <= ec.End {
bNaNs = append(bNaNs, nan)
tStart += ec.Step
}
}
tmp.Values = append(tmp.Values, bNaNs...)
rvs = append(rvs, &tmp)
}
qt.Printf("resulting series=%d", len(rvs))
return rvs, nil
return rvs, true
}
type rollupResultCacheMetainfo struct {
@ -733,9 +782,9 @@ func (mi *rollupResultCacheMetainfo) AddKey(key rollupResultCacheKey, start, end
end: end,
key: key,
})
if len(mi.entries) > 30 {
if len(mi.entries) > 10 {
// Remove old entries.
mi.entries = append(mi.entries[:0], mi.entries[10:]...)
mi.entries = append(mi.entries[:0], mi.entries[5:]...)
}
}

103
app/vmselect/promql/rollup_result_cache_test.go
View file

@ -1,6 +1,7 @@
package promql
import (
"fmt"
"testing"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
@ -245,6 +246,7 @@ func TestRollupResultCache(t *testing.T) {
Timestamps: []int64{1000, 1200, 1400, 1600, 1800, 2000},
Values: []float64{1, 2, 3, 4, 5, 6},
}
ts.MetricName.MetricGroup = []byte(fmt.Sprintf("metric %d", i))
tss = append(tss, ts)
}
rollupResultCacheV.PutSeries(nil, ec, fe, window, tss)
@ -255,6 +257,29 @@ func TestRollupResultCache(t *testing.T) {
testTimeseriesEqual(t, tssResult, tss)
})
// Store series with identical naming (they shouldn't be stored)
t.Run("duplicate-series", func(t *testing.T) {
ResetRollupResultCache()
tss := []*timeseries{
{
Timestamps: []int64{800, 1000, 1200},
Values: []float64{0, 1, 2},
},
{
Timestamps: []int64{800, 1000, 1200},
Values: []float64{0, 1, 2},
},
}
rollupResultCacheV.PutSeries(nil, ec, fe, window, tss)
tssResult, newStart := rollupResultCacheV.GetSeries(nil, ec, fe, window)
if newStart != ec.Start {
t.Fatalf("unexpected newStart; got %d; want %d", newStart, ec.Start)
}
if len(tssResult) != 0 {
t.Fatalf("unexpected non-empty series returned")
}
})
// Store multiple time series
t.Run("multi-timeseries", func(t *testing.T) {
ResetRollupResultCache()
@ -294,7 +319,7 @@ func TestRollupResultCache(t *testing.T) {
}
func TestMergeTimeseries(t *testing.T) {
func TestMergeSeries(t *testing.T) {
ec := &EvalConfig{
Start: 1000,
End: 2000,
@ -311,9 +336,9 @@ func TestMergeTimeseries(t *testing.T) {
Values: []float64{1, 2, 3, 4, 5, 6},
},
}
tss, err := mergeTimeseries(nil, a, b, 1000, ec)
if err != nil {
t.Fatalf("unexpected error: %s", err)
tss, ok := mergeSeries(nil, a, b, 1000, ec)
if !ok {
t.Fatalf("unexpected failure to merge series")
}
tssExpected := []*timeseries{
{
@ -331,9 +356,9 @@ func TestMergeTimeseries(t *testing.T) {
Values: []float64{3, 4, 5, 6},
},
}
tss, err := mergeTimeseries(nil, a, b, bStart, ec)
if err != nil {
t.Fatalf("unexpected error: %s", err)
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if !ok {
t.Fatalf("unexpected failure to merge series")
}
tssExpected := []*timeseries{
{
@ -351,9 +376,9 @@ func TestMergeTimeseries(t *testing.T) {
},
}
b := []*timeseries{}
tss, err := mergeTimeseries(nil, a, b, bStart, ec)
if err != nil {
t.Fatalf("unexpected error: %s", err)
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if !ok {
t.Fatalf("unexpected failure to merge series")
}
tssExpected := []*timeseries{
{
@ -376,9 +401,9 @@ func TestMergeTimeseries(t *testing.T) {
Values: []float64{3, 4, 5, 6},
},
}
tss, err := mergeTimeseries(nil, a, b, bStart, ec)
if err != nil {
t.Fatalf("unexpected error: %s", err)
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if !ok {
t.Fatalf("unexpected failure to merge series")
}
tssExpected := []*timeseries{
{
@ -403,9 +428,9 @@ func TestMergeTimeseries(t *testing.T) {
},
}
b[0].MetricName.MetricGroup = []byte("foo")
tss, err := mergeTimeseries(nil, a, b, bStart, ec)
if err != nil {
t.Fatalf("unexpected error: %s", err)
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if !ok {
t.Fatalf("unexpected failure to merge series")
}
tssExpected := []*timeseries{
{
@ -425,6 +450,52 @@ func TestMergeTimeseries(t *testing.T) {
}
testTimeseriesEqual(t, tss, tssExpected)
})
t.Run("duplicate-series-a", func(t *testing.T) {
a := []*timeseries{
{
Timestamps: []int64{1000, 1200},
Values: []float64{2, 1},
},
{
Timestamps: []int64{1000, 1200},
Values: []float64{3, 3},
},
}
b := []*timeseries{
{
Timestamps: []int64{1400, 1600, 1800, 2000},
Values: []float64{3, 4, 5, 6},
},
}
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if ok {
t.Fatalf("expecting failre to merge series")
}
testTimeseriesEqual(t, tss, nil)
})
t.Run("duplicate-series-b", func(t *testing.T) {
a := []*timeseries{
{
Timestamps: []int64{1000, 1200},
Values: []float64{1, 2},
},
}
b := []*timeseries{
{
Timestamps: []int64{1400, 1600, 1800, 2000},
Values: []float64{3, 4, 5, 6},
},
{
Timestamps: []int64{1400, 1600, 1800, 2000},
Values: []float64{13, 14, 15, 16},
},
}
tss, ok := mergeSeries(nil, a, b, bStart, ec)
if ok {
t.Fatalf("expecting failre to merge series")
}
testTimeseriesEqual(t, tss, nil)
})
}
func testTimeseriesEqual(t *testing.T, tss, tssExpected []*timeseries) {

2
docs/CHANGELOG.md
View file

@ -30,6 +30,8 @@ The sandbox cluster installation is running under the constant load generated by
* FEATURE: dashboards: use `version` instead of `short_version` in version change annotation for single/cluster dashboards. The update should reflect version changes even if different flavours of the same release were applied (custom builds).
* BUGFIX: fix a bug, which could result in improper results and/or to `cannot merge series: duplicate series found` error during [range query](https://docs.victoriametrics.com/keyConcepts.html#range-query) query execution. The issue has been introduced in [v1.95.0](https://docs.victoriametrics.com/CHANGELOG.html#v1950). See [this bugreport](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5332) for details.
## [v1.95.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.95.0)
Released at 2023-11-15