promql

Documentation

Overview

Package promql is an optional adapter that bridges the storage fetch contract (query/fetch) to the Prometheus storage.Queryable interface. It does not own a PromQL engine: the embedder (e.g. go-faster/oteldb, which already has PromQL/LogQL/TraceQL engines) drives its own promql.Engine over the Queryable this package returns. The storage library proper stops at the fetch seam and stays language- and Prometheus-free; this package is the only one importing github.com/prometheus/prometheus, and importing it is opt-in.

Condition extraction lives here (the language layer), never in storage: a Prometheus matcher that can match the empty string (e.g. `!=`, `!~`, `=""`) would wrongly exclude series that lack the label if pushed into the postings index, so only index-safe matchers are pushed down; every returned series is then re-checked against the full matcher set.

Index

• func MatchesAll(lset labels.Labels, ms []*labels.Matcher) bool
• func PromLabels(s signal.Series) labels.Labels
• func PushableMatchers(ms []*labels.Matcher) []fetch.Matcher
• type Queryable
  • func NewQueryable(fetcher fetch.Fetcher, tenant signal.TenantID) *Queryable
  • func (q *Queryable) Querier(mint, maxt int64) (storage.Querier, error)

Functions

func MatchesAll

func MatchesAll(lset labels.Labels, ms []*labels.Matcher) bool

MatchesAll reports whether a series' labels satisfy every matcher, treating an absent label as the empty string (Prometheus semantics). It is the post-fetch re-check companion to PushableMatchers: exported so an embedder's pushdown path re-checks the full matcher set the same way Queryable does.

func PromLabels

func PromLabels(s signal.Series) labels.Labels

PromLabels projects a storage series identity to a Prometheus label set: every resource, scope, and (folded) point attribute becomes a label, with the internal reserved labels (except __name__) hidden. Scope name/version are exposed under the otel.scope.* keys, the same labels the head indexes.

PromLabels is exported so an embedder can render a signal.Series (e.g. the identity carried alongside an github.com/oteldb/storage.Storage.AggregateMetrics result) as PromQL labels without duplicating this projection.

func PushableMatchers

func PushableMatchers(ms []*labels.Matcher) []fetch.Matcher

PushableMatchers returns fetch matchers for the index-safe subset: matchers that do not match the empty string. A matcher that matches "" (negated/absent) cannot prune via the postings index without wrongly dropping series that lack the label, so it is enforced only by the post-fetch re-check in MatchesAll.

It is exported so an embedder building a pushdown path over the fetch/aggregate seam (e.g. oteldb's *_over_time aggregate pushdown) can lower the same index-safe matcher set the Queryable uses, keeping matcher translation in one place.

Types

type Queryable

type Queryable struct {
	// contains filtered or unexported fields
}

Queryable adapts a fetch.Fetcher (one tenant's engine) to the Prometheus storage.Queryable interface for a single tenant.

func NewQueryable

func NewQueryable(fetcher fetch.Fetcher, tenant signal.TenantID) *Queryable

NewQueryable returns a Prometheus storage.Queryable backed by fetcher for the given tenant. A single Queryable reused across queries (the embedder's per-tenant adapter) memoizes label projections, so repeated queries pay the projection cost once per series.

func (*Queryable) Querier

func (q *Queryable) Querier(mint, maxt int64) (storage.Querier, error)

Querier returns a querier over [mint, maxt] (Prometheus milliseconds).