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Optimise query_range by computing join signatures just once (#9360)

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* Add benchmark case for many-to-one join

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>

* query_range: compute join signatures just once

For an expression like `a + on(p,q) b`, extract the `p,q` part from each
series once, instead of re-computing at every step of the range.

Although there was a cache, computing the key by concatenating all
labels was expensive.

Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
This commit is contained in:
Bryan Boreham 2021-09-21 11:28:39 +01:00 committed by GitHub
parent 7d105277fe
commit c4942ef3b7
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 41 additions and 51 deletions
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4
promql/bench_test.go
View File

@ -175,6 +175,10 @@ func BenchmarkRangeQuery(b *testing.B) {
{
expr: "histogram_quantile(0.9, rate(h_X[5m]))",
},
// Many-to-one join.
{
expr: "a_X + on(l) group_right a_one",
},
}
// X in an expr will be replaced by different metric sizes.

88
promql/engine.go
View File

@ -913,6 +913,8 @@ func (ev *evaluator) Eval(expr parser.Expr) (v parser.Value, ws storage.Warnings
type EvalSeriesHelper struct {
// The grouping key used by aggregation.
groupingKey uint64
// Used to map left-hand to right-hand in binary operations.
signature string
}
// EvalNodeHelper stores extra information and caches for evaluating a single node across steps.
@ -925,8 +927,6 @@ type EvalNodeHelper struct {
// Caches.
// DropMetricName and label_*.
Dmn map[uint64]labels.Labels
// signatureFunc.
sigf map[string]string
// funcHistogramQuantile.
signatureToMetricWithBuckets map[string]*metricWithBuckets
// label_replace.
@ -957,23 +957,6 @@ func (enh *EvalNodeHelper) DropMetricName(l labels.Labels) labels.Labels {
return ret
}
func (enh *EvalNodeHelper) signatureFunc(on bool, names ...string) func(labels.Labels) string {
if enh.sigf == nil {
enh.sigf = make(map[string]string, len(enh.Out))
}
f := signatureFunc(on, enh.lblBuf, names...)
return func(l labels.Labels) string {
enh.lblBuf = l.Bytes(enh.lblBuf)
ret, ok := enh.sigf[string(enh.lblBuf)]
if ok {
return ret
}
ret = f(l)
enh.sigf[string(enh.lblBuf)] = ret
return ret
}
}
// rangeEval evaluates the given expressions, and then for each step calls
// the given funcCall with the values computed for each expression at that
// step. The return value is the combination into time series of all the
@ -1432,22 +1415,28 @@ func (ev *evaluator) eval(expr parser.Expr) (parser.Value, storage.Warnings) {
return append(enh.Out, Sample{Point: Point{V: val}}), nil
}, e.LHS, e.RHS)
case lt == parser.ValueTypeVector && rt == parser.ValueTypeVector:
// Function to compute the join signature for each series.
buf := make([]byte, 0, 1024)
sigf := signatureFunc(e.VectorMatching.On, buf, e.VectorMatching.MatchingLabels...)
initSignatures := func(series labels.Labels, h *EvalSeriesHelper) {
h.signature = sigf(series)
}
switch e.Op {
case parser.LAND:
return ev.rangeEval(nil, func(v []parser.Value, _ [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorAnd(v[0].(Vector), v[1].(Vector), e.VectorMatching, enh), nil
return ev.rangeEval(initSignatures, func(v []parser.Value, sh [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorAnd(v[0].(Vector), v[1].(Vector), e.VectorMatching, sh[0], sh[1], enh), nil
}, e.LHS, e.RHS)
case parser.LOR:
return ev.rangeEval(nil, func(v []parser.Value, _ [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorOr(v[0].(Vector), v[1].(Vector), e.VectorMatching, enh), nil
return ev.rangeEval(initSignatures, func(v []parser.Value, sh [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorOr(v[0].(Vector), v[1].(Vector), e.VectorMatching, sh[0], sh[1], enh), nil
}, e.LHS, e.RHS)
case parser.LUNLESS:
return ev.rangeEval(nil, func(v []parser.Value, _ [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorUnless(v[0].(Vector), v[1].(Vector), e.VectorMatching, enh), nil
return ev.rangeEval(initSignatures, func(v []parser.Value, sh [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorUnless(v[0].(Vector), v[1].(Vector), e.VectorMatching, sh[0], sh[1], enh), nil
}, e.LHS, e.RHS)
default:
return ev.rangeEval(nil, func(v []parser.Value, _ [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorBinop(e.Op, v[0].(Vector), v[1].(Vector), e.VectorMatching, e.ReturnBool, enh), nil
return ev.rangeEval(initSignatures, func(v []parser.Value, sh [][]EvalSeriesHelper, enh *EvalNodeHelper) (Vector, storage.Warnings) {
return ev.VectorBinop(e.Op, v[0].(Vector), v[1].(Vector), e.VectorMatching, e.ReturnBool, sh[0], sh[1], enh), nil
}, e.LHS, e.RHS)
}
@ -1774,62 +1763,59 @@ func (ev *evaluator) matrixIterSlice(it *storage.BufferedSeriesIterator, mint, m
return out
}
func (ev *evaluator) VectorAnd(lhs, rhs Vector, matching *parser.VectorMatching, enh *EvalNodeHelper) Vector {
func (ev *evaluator) VectorAnd(lhs, rhs Vector, matching *parser.VectorMatching, lhsh, rhsh []EvalSeriesHelper, enh *EvalNodeHelper) Vector {
if matching.Card != parser.CardManyToMany {
panic("set operations must only use many-to-many matching")
}
sigf := enh.signatureFunc(matching.On, matching.MatchingLabels...)
// The set of signatures for the right-hand side Vector.
rightSigs := map[string]struct{}{}
// Add all rhs samples to a map so we can easily find matches later.
for _, rs := range rhs {
rightSigs[sigf(rs.Metric)] = struct{}{}
for _, sh := range rhsh {
rightSigs[sh.signature] = struct{}{}
}
for _, ls := range lhs {
for i, ls := range lhs {
// If there's a matching entry in the right-hand side Vector, add the sample.
if _, ok := rightSigs[sigf(ls.Metric)]; ok {
if _, ok := rightSigs[lhsh[i].signature]; ok {
enh.Out = append(enh.Out, ls)
}
}
return enh.Out
}
func (ev *evaluator) VectorOr(lhs, rhs Vector, matching *parser.VectorMatching, enh *EvalNodeHelper) Vector {
func (ev *evaluator) VectorOr(lhs, rhs Vector, matching *parser.VectorMatching, lhsh, rhsh []EvalSeriesHelper, enh *EvalNodeHelper) Vector {
if matching.Card != parser.CardManyToMany {
panic("set operations must only use many-to-many matching")
}
sigf := enh.signatureFunc(matching.On, matching.MatchingLabels...)
leftSigs := map[string]struct{}{}
// Add everything from the left-hand-side Vector.
for _, ls := range lhs {
leftSigs[sigf(ls.Metric)] = struct{}{}
for i, ls := range lhs {
leftSigs[lhsh[i].signature] = struct{}{}
enh.Out = append(enh.Out, ls)
}
// Add all right-hand side elements which have not been added from the left-hand side.
for _, rs := range rhs {
if _, ok := leftSigs[sigf(rs.Metric)]; !ok {
for j, rs := range rhs {
if _, ok := leftSigs[rhsh[j].signature]; !ok {
enh.Out = append(enh.Out, rs)
}
}
return enh.Out
}
func (ev *evaluator) VectorUnless(lhs, rhs Vector, matching *parser.VectorMatching, enh *EvalNodeHelper) Vector {
func (ev *evaluator) VectorUnless(lhs, rhs Vector, matching *parser.VectorMatching, lhsh, rhsh []EvalSeriesHelper, enh *EvalNodeHelper) Vector {
if matching.Card != parser.CardManyToMany {
panic("set operations must only use many-to-many matching")
}
sigf := enh.signatureFunc(matching.On, matching.MatchingLabels...)
rightSigs := map[string]struct{}{}
for _, rs := range rhs {
rightSigs[sigf(rs.Metric)] = struct{}{}
for _, sh := range rhsh {
rightSigs[sh.signature] = struct{}{}
}
for _, ls := range lhs {
if _, ok := rightSigs[sigf(ls.Metric)]; !ok {
for i, ls := range lhs {
if _, ok := rightSigs[lhsh[i].signature]; !ok {
enh.Out = append(enh.Out, ls)
}
}
@ -1837,17 +1823,17 @@ func (ev *evaluator) VectorUnless(lhs, rhs Vector, matching *parser.VectorMatchi
}
// VectorBinop evaluates a binary operation between two Vectors, excluding set operators.
func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *parser.VectorMatching, returnBool bool, enh *EvalNodeHelper) Vector {
func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *parser.VectorMatching, returnBool bool, lhsh, rhsh []EvalSeriesHelper, enh *EvalNodeHelper) Vector {
if matching.Card == parser.CardManyToMany {
panic("many-to-many only allowed for set operators")
}
sigf := enh.signatureFunc(matching.On, matching.MatchingLabels...)
// The control flow below handles one-to-one or many-to-one matching.
// For one-to-many, swap sidedness and account for the swap when calculating
// values.
if matching.Card == parser.CardOneToMany {
lhs, rhs = rhs, lhs
lhsh, rhsh = rhsh, lhsh
}
// All samples from the rhs hashed by the matching label/values.
@ -1861,8 +1847,8 @@ func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *
rightSigs := enh.rightSigs
// Add all rhs samples to a map so we can easily find matches later.
for _, rs := range rhs {
sig := sigf(rs.Metric)
for i, rs := range rhs {
sig := rhsh[i].signature
// The rhs is guaranteed to be the 'one' side. Having multiple samples
// with the same signature means that the matching is many-to-many.
if duplSample, found := rightSigs[sig]; found {
@ -1892,8 +1878,8 @@ func (ev *evaluator) VectorBinop(op parser.ItemType, lhs, rhs Vector, matching *
// For all lhs samples find a respective rhs sample and perform
// the binary operation.
for _, ls := range lhs {
sig := sigf(ls.Metric)
for i, ls := range lhs {
sig := lhsh[i].signature
rs, found := rightSigs[sig] // Look for a match in the rhs Vector.
if !found {