discord9 aa30968d43 feat(promql): execute native scalar roots and literal broadcasts (#9936)
I hereby agree to the terms of the [GreptimeDB
CLA](https://github.com/GreptimeTeam/.github/blob/main/CLA.md).

## Refer to a related PR or issue link (optional)

Stacked on #9868 (`feat/narthex-fused-wiring`, currently at
`990d932198ab0c5e41b724a54d990e5a8ffc8acb`). This change needs that PR's
unmerged `FusedSeries`/`SeriesScan`/in-process native route, so the base
is its branch; GitHub will retarget to `narthex` once #9868 merges.

## What's changed and what's your intention?

Enable the existing opt-in native PromQL route for literal vector/scalar
arithmetic such as `x * 100`, unary negation such as `-x`, and constant
scalar statements such as `1 + 2`. These public entries return ordinary
nonempty query RecordBatches with the same values and output schema as
the existing planner.

- Traverse unary and binary expression operands when locating the one
selector and its range requirements. Constant-only statements reuse the
existing constant evaluator and statement grid; unsupported shapes still
use the existing planner.
- Execute constant Scalar roots as one unlabelled evaluated chunk on the
full statement grid, with existing memory admission, output metrics and
error/cleanup paths. A no-input tree has genuinely zero logical/physical
children rather than a discarded placeholder scan.
- Keep each raw input partition attached to its own `FusedSeriesExec`
evaluator. This change adds neither an input-side Coalesce nor a
SeriesFrame exchange. Ordinary output collection continues to use
DataFusion.
- Cover scalar NaN/negative-zero/EOF/memory boundaries, child arity and
output schemas, independent lazy input progress, and the actual public
HTTP/query-handler route. The standalone single-region fixture persists
four disjoint input batches: for both broadcast and unary queries, all
four input/native partitions perform work and the complete result is
exactly 24 labelled timestamp/value rows. A four-stream barrier test
collected by DataFusion verifies concurrent progress; this is not a
CPU-overlap or speedup benchmark.
- Add a generated SQLness compatibility case for scalar arithmetic,
broadcast and unary results, rerun successfully without result changes.

Scope: constant scalar roots and literal broadcasts only.
`scalar(vector)` adaptation, dynamic per-grid scalar
arithmetic/broadcast, global Vector/Select and Complete Aggregate wiring
are separate work and are not enabled here. The experimental
configuration/request gates and current unsupported-shape fallback
remain in place. No persisted or remote wire format changes are
introduced; internal Fused constructor callers are migrated together.

Verification on this exact HEAD
(`d9eb9778f113dd9bd6125305a9ea447b4aa6ab1d`, restacked onto the current
dependency
`990d932198ab0c5e41b724a54d990e5a8ffc8acb`), exit 0:

```text
cargo fmt --all -- --check
git diff --check
cargo check --locked -p promql -p query --tests
cargo check --locked -p tests-integration --lib --test main
cargo nextest run --locked -p promql -p query --retries 0
  1870 passed, 2 skipped
cargo nextest run --locked -p tests-integration --test main --retries 0 \
  -E 'test(=integration_http_file_test::test_native_promql_route_plans_the_query) | test(=integration_http_file_test::test_prometheus_native_promql_route)'
  2 passed, 770 filtered out   (four real input partitions, exact 24 values)
cargo nextest run --locked -p tests-integration --lib --retries 0 -E 'test(native_promql_)'
  4 passed, 251 filtered out   (upstream VIEW/metric/ANALYZE compatibility)
cargo clippy --locked -p promql -p query --all-targets -- -D warnings
cargo clippy --locked -p tests-integration --lib --test main -- -D warnings
```

SQLness (generated, then rerun with an unchanged result):

```text
/mnt/nvme_rust/rust-targets-2/d-scalar-entry/debug/sqlness-runner bare \
  --bins-dir .../debug --case-dir <isolated root> --test-filter '^standalone:scalar_entry$' --jobs 1
```

This SQLness case uses the default public compatibility route, not the
native request flag; it does not replace the native execution assertions
above. Full workspace `make test`/`make clippy`/udeps and external CI
have not been run for this change.

## PR Checklist
Please convert it to a draft if some of the following conditions are not
met.

- [x] I have written the necessary rustdoc comments.
- [x] I have added the necessary unit tests and integration tests.
- [ ] This PR requires documentation updates.
- [x] API changes are backward compatible.
- [x] Schema or data changes are backward compatible.
- [ ] This PR needs to be backported to release branches, and I have
added the `backport-<target>` labels (e.g. `backport-v1.3` targets
`release/v1.3`).
2026-10-26 10:10:40 +08:00
2023-08-10 08:08:37 +00:00
2023-06-25 11:05:46 +08:00
2023-11-09 10:38:12 +00:00

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Introduction

GreptimeDB is an open-source observability database. Metrics, logs, and traces run on one columnar engine over object storage and share one table model: tags, timestamp, and fields. When signals carry common identifiers such as service, host, or trace ID, you can correlate them in SQL without moving data between databases.

Ingest through OpenTelemetry, Prometheus Remote Write, Loki Push, or Elasticsearch Bulk. Use SQL across observability data and PromQL for metrics. Migrate ingestion one signal at a time without rebuilding your collectors.

One Query Across Signals

OpenTelemetry ingestion writes spans to opentelemetry_traces and log records to opentelemetry_logs. Both tables carry trace_id, so correlating them is a join:

-- The slowest failed spans in the last hour,
-- with the log lines emitted inside those same traces.
SELECT
    t.service_name,
    t.span_name,
    t.duration_nano / 1000000 AS duration_ms,
    l.timestamp AS log_time,
    l.severity_text,
    l.body
FROM opentelemetry_traces t
JOIN opentelemetry_logs l ON l.trace_id = t.trace_id
WHERE t.timestamp > now() - INTERVAL '1' HOUR
  AND t.span_status_code = 'STATUS_CODE_ERROR'
ORDER BY t.duration_nano DESC
LIMIT 20;

Metrics join the same way, on any tag the tables share, such as service, host, or pod.

Why You Might Use It

  • You run Prometheus plus Loki or Elasticsearch and want one backend instead of three
  • You have outgrown Prometheus on cardinality or retention and don't want the Thanos/Mimir operational surface
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  • You need long retention on object storage without a separate analytics stack
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Learn more in Why GreptimeDB.

What's Supported

Ingest OpenTelemetry (OTLP), Prometheus Remote Write, Loki Push, Elasticsearch Bulk, InfluxDB line protocol, gRPC
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Built in Retention policies, downsampling, continuous aggregation, explicit table partitioning, and inverted / skipping / fulltext indexes

Compute and storage are disaggregated: object storage holds the data, while memory and local-disk caches keep recent and frequently queried data close to compute.

GreptimeDB Overview

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Compatibility and Migration

Compatibility is per protocol, and query-side coverage is narrower than ingestion.

Compatible Not compatible
Prometheus Remote Write ingestion; PromQL queries Gaps are listed in PromQL compatibility
Loki Push ingestion; dual-write through Grafana Alloy makes the cutover gradual LogQL and the rest of the Loki query API
Elasticsearch _bulk ingestion in the open-source core; QueryDSL partially, in Enterprise Most other Elasticsearch APIs

Limitations and Edition Boundary

Cluster deployment, object storage, the Flow engine, and every ingestion protocol listed above are in the Apache-2.0 build. Repartitioning, region migration, and index creation are manual operations there.

Read replicas, workload isolation, and automated repartitioning are GreptimeDB Enterprise features, along with enterprise security and governance. The Enterprise overview has the current list, and pricing has the edition comparison.

Architecture

GreptimeDB can run in two modes:

  • Standalone — single binary for development and small deployments.
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For deeper coverage, see the architecture doc or DeepWiki.

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Read more in the full Install Guide.

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Getting Started

Build From Source

Prerequisites:

  • Rust toolchain — stable, pinned by rust-toolchain.toml
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Build and run:

make                          # build greptime binary
cargo run -- standalone start # start in standalone mode

Common dev commands:

make fmt            # format Rust code
make clippy         # lint (fails on warnings)
make test           # unit + integration tests (uses cargo-nextest)
make sqlness-test   # SQL regression tests

See the Contribution Guidelines for the full developer workflow.

Tools & Extensions

Project Status

GreptimeDB is generally available, with stable APIs and regular releases. It runs in production at scale — OceanBase Cloud operates 80+ GreptimeDB clusters managing 300 TB of logs, cutting log storage cost by 60%+ after migrating from Grafana Loki. See more in case studies.

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License

GreptimeDB is an open-core project. Its core is licensed under the Apache License 2.0.

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Contributing

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Acknowledgement

Special thanks to all contributors! See AUTHOR.md.


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Open-source, cloud-native, unified observability database for metrics, logs and traces, supporting SQL/PromQL/Streaming.
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