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Add holt_winters backwards compatibility in Cortex parser #7223

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Add holt_winters backwards compatibility in Cortex parser #7223

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add holt_winters to cortex parser
afhassan Jan 20, 2026
1b59eb9
Merge branch 'cortexproject:master' into fix-holt-winters
afhassan Jan 20, 2026
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12 changes: 12 additions & 0 deletions pkg/parser/parser.go
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ package parser
import (
"maps"

"github.com/prometheus/prometheus/promql"
promqlparser "github.com/prometheus/prometheus/promql/parser"
"github.com/thanos-io/promql-engine/execution/parse"
)
Expand All @@ -13,6 +14,17 @@ func buildFunctions() map[string]*promqlparser.Function {
fns := make(map[string]*promqlparser.Function, len(promqlparser.Functions))
maps.Copy(fns, promqlparser.Functions)
maps.Copy(fns, parse.XFunctions)

// The holt_winters function was renamed to double_exponential_smoothing and marked experimental in Prometheus v3.
// Register holt_winters as an alias in cortexparser to maintain backward compatibility.
if des, ok := fns["double_exponential_smoothing"]; ok {
holtWinters := *des
holtWinters.Experimental = false
holtWinters.Name = "holt_winters"
fns["holt_winters"] = &holtWinters
promql.FunctionCalls["holt_winters"] = promql.FunctionCalls["double_exponential_smoothing"]
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@yeya24 yeya24 Jan 21, 2026

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Can you add a test?
Also I am trying to understand why our integration test didn't capture this issue before. https://github.com/cortexproject/cortex/blob/master/integration/backward_compatibility_test.go#L161

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@yeya24 yeya24 Jan 21, 2026

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Also I think this should be behind a feature flag as well. Same as

cortex/pkg/querier/querier.go

Line 723 in caedb08

func EnableExperimentalPromQLFunctions(enablePromQLExperimentalFunctions, enableHoltWinters bool) {
. Even though we hardcode to true today we may want to expose a flag so that we can disable the fallback in the future.

}

return fns
}

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