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Hints: Separating out the range and offsets of PromQL subqueries (#7667)

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Fix #7629

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>
This commit is contained in:
Julien Pivotto 2020-08-11 08:21:39 +02:00 committed by GitHub
parent 4ae2ef94e0
commit 20ab94fedf
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 35 additions and 22 deletions
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40
promql/engine.go
View file

@ -576,35 +576,39 @@ func (ng *Engine) execEvalStmt(ctx context.Context, query *query, s *parser.Eval
return mat, warnings, nil
}
// cumulativeSubqueryOffset returns the sum of range and offset of all subqueries in the path.
func (ng *Engine) cumulativeSubqueryOffset(path []parser.Node) time.Duration {
var subqOffset time.Duration
// subqueryOffsetRange returns the sum of offsets and ranges of all subqueries in the path.
func (ng *Engine) subqueryOffsetRange(path []parser.Node) (time.Duration, time.Duration) {
var (
subqOffset time.Duration
subqRange time.Duration
)
for _, node := range path {
switch n := node.(type) {
case *parser.SubqueryExpr:
subqOffset += n.Range + n.Offset
subqOffset += n.Offset
subqRange += n.Range
}
}
return subqOffset
return subqOffset, subqRange
}
func (ng *Engine) findMinTime(s *parser.EvalStmt) time.Time {
var maxOffset time.Duration
parser.Inspect(s.Expr, func(node parser.Node, path []parser.Node) error {
subqOffset := ng.cumulativeSubqueryOffset(path)
subqOffset, subqRange := ng.subqueryOffsetRange(path)
switch n := node.(type) {
case *parser.VectorSelector:
if maxOffset < ng.lookbackDelta+subqOffset {
maxOffset = ng.lookbackDelta + subqOffset
if maxOffset < ng.lookbackDelta+subqOffset+subqRange {
maxOffset = ng.lookbackDelta + subqOffset + subqRange
}
if n.Offset+ng.lookbackDelta+subqOffset > maxOffset {
maxOffset = n.Offset + ng.lookbackDelta + subqOffset
if n.Offset+ng.lookbackDelta+subqOffset+subqRange > maxOffset {
maxOffset = n.Offset + ng.lookbackDelta + subqOffset + subqRange
}
case *parser.MatrixSelector:
if maxOffset < n.Range+subqOffset {
maxOffset = n.Range + subqOffset
if maxOffset < n.Range+subqOffset+subqRange {
maxOffset = n.Range + subqOffset + subqRange
}
if m := n.VectorSelector.(*parser.VectorSelector).Offset + n.Range + subqOffset; m > maxOffset {
if m := n.VectorSelector.(*parser.VectorSelector).Offset + n.Range + subqOffset + subqRange; m > maxOffset {
maxOffset = m
}
}
@ -629,13 +633,13 @@ func (ng *Engine) populateSeries(querier storage.Querier, s *parser.EvalStmt) {
}
// We need to make sure we select the timerange selected by the subquery.
// The cumulativeSubqueryOffset function gives the sum of range and the offset.
// TODO(gouthamve): Consider optimising it by separating out the range and offsets, and subtracting the offsets
// from end also. See: https://github.com/prometheus/prometheus/issues/7629.
// The subqueryOffsetRange function gives the sum of range and the
// sum of offset.
// TODO(bwplotka): Add support for better hints when subquerying. See: https://github.com/prometheus/prometheus/issues/7630.
subqOffset := ng.cumulativeSubqueryOffset(path)
subqOffset, subqRange := ng.subqueryOffsetRange(path)
offsetMilliseconds := durationMilliseconds(subqOffset)
hints.Start = hints.Start - offsetMilliseconds
hints.Start = hints.Start - offsetMilliseconds - durationMilliseconds(subqRange)
hints.End = hints.End - offsetMilliseconds
if evalRange == 0 {
hints.Start = hints.Start - durationMilliseconds(ng.lookbackDelta)

8
promql/engine_test.go
View file

@ -289,12 +289,12 @@ func TestSelectHintsSetCorrectly(t *testing.T) {
}, {
query: "count_over_time(foo[2m:1s] offset 10s)", start: 300000,
expected: []*storage.SelectHints{
{Start: 165000, End: 300000, Func: "count_over_time"},
{Start: 165000, End: 290000, Func: "count_over_time"},
},
}, {
query: "count_over_time((foo offset 10s)[2m:1s] offset 10s)", start: 300000,
expected: []*storage.SelectHints{
{Start: 155000, End: 290000, Func: "count_over_time"},
{Start: 155000, End: 280000, Func: "count_over_time"},
},
}, {
@ -325,12 +325,12 @@ func TestSelectHintsSetCorrectly(t *testing.T) {
}, {
query: "count_over_time(foo[2m:1s] offset 10s)", start: 300000, end: 500000,
expected: []*storage.SelectHints{
{Start: 165000, End: 500000, Func: "count_over_time", Step: 1000},
{Start: 165000, End: 490000, Func: "count_over_time", Step: 1000},
},
}, {
query: "count_over_time((foo offset 10s)[2m:1s] offset 10s)", start: 300000, end: 500000,
expected: []*storage.SelectHints{
{Start: 155000, End: 490000, Func: "count_over_time", Step: 1000},
{Start: 155000, End: 480000, Func: "count_over_time", Step: 1000},
},
}, {
query: "sum by (dim1) (foo)", start: 10000,

9
promql/testdata/selectors.test vendored
View file

@ -57,3 +57,12 @@ eval instant at 0s http_requests{foo!~"bar", job="api-server"}
eval instant at 0s http_requests{foo!~"bar", job="api-server", instance="1", x!="y", z="", group!=""}
http_requests{job="api-server", instance="1", group="production"} 0
http_requests{job="api-server", instance="1", group="canary"} 0
clear
load 1m
metric1{a="a"} 0+1x100
metric2{b="b"} 0+1x50
eval instant at 90m metric1 offset 15m or metric2 offset 45m
metric1{a="a"} 75
metric2{b="b"} 45