Yvan Wang 180e2716fc fix(log-store): make raft-engine periodic WAL sync actually fsync (#9715)
* fix(log-store): make raft-engine periodic WAL sync actually fsync

On raft-engine 0.4.2, Engine::sync() writes an empty LogBatch and
write() returns before fsync (tikv/raft-engine#395). The periodic
sync task therefore never durable-flushed acknowledged WAL data.

Work around by writing a minimal non-empty marker with sync=true so
the fsync path is reached until a crates.io release includes
tikv/raft-engine#400.

Fixes #9712

Signed-off-by: Yvan Wang <131545713+BootstrapperSBL@users.noreply.github.com>

* perf(log-store): reuse LogBatch across periodic WAL syncs

Keep the periodic sync task's LogBatch across ticks instead of
allocating a fresh one (4 KiB encode buffer plus item vec) every
period. A successful Engine::write drains the batch but retains its
buffers; after a failed write or a panicked blocking task the batch is
discarded and recreated on the next tick, since it may be left
partially encoded.

Keep the marker put rather than deleting an empty key: the put
overwrites a single key, whereas every delete would become a recovery
tombstone that raft-engine keeps in memory while replaying append
files.

Also document that the marker value must not decode as a NamespaceImpl
(the marker key lies inside the range scanned by list_namespaces), add
a test covering batch reuse and namespace listing, and apply rustfmt.

Refs #9712

Signed-off-by: Yvan Wang <131545713+BootstrapperSBL@users.noreply.github.com>

---------

Signed-off-by: Yvan Wang <131545713+BootstrapperSBL@users.noreply.github.com>
2026-10-28 02:34:56 +00:00
2023-08-10 08:08:37 +00:00
2023-06-25 11:05:46 +08:00
2023-11-09 10:38:12 +00:00

GreptimeDB Logo

Metrics, logs, and traces.
One engine, on your infrastructure.

A columnar database for metrics, logs, and traces on object storage. Apache-2.0 licensed core.

User Guide  ·  API Docs  ·  Roadmap 2026  ·  Slack

Stable Canary Nightly Docker Pulls License

stable for production  ·  canary includes pre-releases  ·  nightly is a weekly snapshot of main

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
  • You are hitting Loki's query performance limits as log volume grows
  • You need long retention on object storage without a separate analytics stack
  • You want to query telemetry with SQL, not only a domain query language
  • You are storing GenAI or agent telemetry (OTel GenAI conventions) alongside infrastructure signals

Learn more in Why GreptimeDB.

What's Supported

Ingest OpenTelemetry (OTLP), Prometheus Remote Write, Loki Push, Elasticsearch Bulk, InfluxDB line protocol, gRPC
Query SQL, PromQL, Jaeger-compatible trace queries, MySQL and PostgreSQL wire protocols
Storage S3, GCS, Azure Blob and S3-compatible endpoints as primary storage, with memory and local-disk caches
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

Benchmarks

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.
  • Distributed — four components, each independently scalable:
    • Frontend — protocol entry (OTel, Prometheus, MySQL/PostgreSQL, gRPC, ingestion APIs for Elasticsearch/InfluxDB/Loki) and the distributed query engine. Stateless, scales horizontally.
    • Datanode — region engine with WAL, memtable, SST, cache, compaction, and indexes. Persists data to object storage. Elastic.
    • Metasrv — metadata, routing, repartitioning, and security. Backed by a pluggable KV layer (etcd or RDS).
    • Flownode (optional) — continuous flow computation (streaming and materialized views).

For deeper coverage, see the architecture doc or DeepWiki.

GreptimeDB System Overview

Try GreptimeDB

For AI agents — paste this prompt into your agent:

Read https://docs.greptime.com/SKILL.md and follow the instructions
to deploy, configure, ingest, and query GreptimeDB.
docker run -p 127.0.0.1:4000-4003:4000-4003 \
  -v "$(pwd)/greptimedb_data:/greptimedb_data" \
  --name greptime --rm \
  greptime/greptimedb:latest standalone start \
  --http-addr 0.0.0.0:4000 \
  --grpc-bind-addr 0.0.0.0:4001 \
  --mysql-addr 0.0.0.0:4002 \
  --postgres-addr 0.0.0.0:4003

Dashboard: http://localhost:4000/dashboard

Read more in the full Install Guide.

Troubleshooting:

  • Cannot connect to the database? Ensure that ports 4000, 4001, 4002, and 4003 are not blocked by a firewall or used by other services.
  • Failed to start? Check the container logs with docker logs greptime for further details.

Getting Started

Build From Source

Prerequisites:

  • Rust toolchain — stable, pinned by rust-toolchain.toml
  • Protobuf compiler (>= 3.15)
  • C/C++ building essentials: gcc / g++ / autoconf and the glibc dev package (libc6-dev on Ubuntu, glibc-devel on Fedora)
  • Python toolchain (optional, only for some test scripts)

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.

Release lines and support windows are in the version reference. For where the project is going, read the v1.0 highlights and the 2026 roadmap.

Community

We invite you to engage and contribute!

If GreptimeDB is useful to you, please star the repo.

Known Users

License

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

A small set of peripheral, enterprise-only features are gated behind the enterprise Cargo feature (not built by default) and are governed by the separate GreptimeDB Enterprise License. Source files under that license carry an explicit Enterprise License header.

Commercial Support

Scaling observability on your infrastructure? GreptimeDB Enterprise adds the operational, security, and support layer for production deployments. Contact us for details.

Contributing

Integration CI Codecov

Acknowledgement

Special thanks to all contributors! See AUTHOR.md.


All trademarks, logos, and brand names referenced in this README and in the Overview diagram are the property of their respective owners. Their use is for identification purposes only and does not imply endorsement or affiliation.

S
Description
Open-source, cloud-native, unified observability database for metrics, logs and traces, supporting SQL/PromQL/Streaming.
Readme Apache-2.0
1.6 GiB
Languages
Rust 97.4%
Python 1.8%
Shell 0.4%
JavaScript 0.2%