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feat: increase Drain tree depth from 4 to 30 #24

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Merged
STRRL merged 1 commit into from
Mar 11, 2026
Merged

feat: increase Drain tree depth from 4 to 30 #24

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2 changes: 1 addition & 1 deletion pkg/pattern/drain.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@ type DrainParser struct {
// NewDrainParser creates a DrainParser with default Drain parameters.
func NewDrainParser() (*DrainParser, error) {
d, err := drain3.NewDrain(
drain3.WithDepth(4),
drain3.WithDepth(30),
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@gemini-code-assist gemini-code-assist bot Mar 10, 2026

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medium

While changing the depth, this is a good opportunity to address the magic numbers in this block of parameters. The values 30, 0.4, and the delimiter slice are hardcoded. Defining them as named, package-level constants/variables would improve readability and maintainability.

Additionally, the delimiter slice []string{"|", "=", ","} is duplicated in pkg/pattern/parser.go. This should be defined in one place to avoid inconsistencies.

I suggest defining these at the package level:

const (
	// defaultDrainDepth matches Loki's default LogClusterDepth.
	// Ref: https://github.com/grafana/loki/tree/main/pkg/pattern/drain
	defaultDrainDepth = 30
	defaultDrainSimTh = 0.4
)

// drainExtraDelimiters is also used in parser.go and should be the single source of truth.
var drainExtraDelimiters = []string{"|", "=", ","}

Then, the NewDrain call would be cleaner and safer:

d, err := drain3.NewDrain(
	drain3.WithDepth(defaultDrainDepth),
	drain3.WithSimTh(defaultDrainSimTh),
	drain3.WithExtraDelimiter(drainExtraDelimiters),
)

This would also require updating pkg/pattern/parser.go to use the new shared drainExtraDelimiters variable.

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@chatgpt-codex-connector chatgpt-codex-connector bot Mar 10, 2026

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P1 Badge Revert Drain depth increase that fragments clusters

Increasing WithDepth from 4 to 30 causes Drain to branch on many more leading tokens before similarity matching, so messages that differ in an early non-numeric field (for example token 3–10) are routed to different leaves and never compared as one template. In this repo that is a functional regression because runDrain keeps only clusters with Count > 1 (cmd/lapp/workspace.go:311-314), so the extra singleton clusters are dropped from semantic labeling and pushed into unmatched output, reducing pattern recall for real logs.

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drain3.WithSimTh(0.4),
drain3.WithExtraDelimiter([]string{"|", "=", ","}),
)
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