GreptimeDB vs openGemini

GreptimeDB is an open-source observability database for storing and querying metrics, logs, and traces through a columnar engine and shared SQL layer. It targets append-heavy, time-indexed workloads such as observability and IoT data, rather than general-purpose transactional database work. Users can query signal tables with SQL and metrics with PromQL. Ingestion options include Prometheus Remote Write, OpenTelemetry OTLP/HTTP, Loki Push API, Elasticsearch Bulk API, InfluxDB Line Protocol, MySQL, PostgreSQL, gRPC, and HTTP. Documented integrations include Prometheus, Grafana, Kafka, Apache Flink, Apache Spark, Telegraf, EMQX, and Fluent Bit. It can run standalone or as a horizontally scalable cluster, with Helm charts, Docker images, and binaries for macOS, Linux, Windows, and Android ARM64. The open-source edition lists username/password authentication, user-level read/write access control, and TLS/SSL connections. Enterprise adds features including LDAP, fine-grained RBAC, audit logging, and encryption at rest. The fully managed Enterprise plan costs $290 a month. Open-source users receive community support through Slack and GitHub.

openGemini is a free, open-source distributed database for storing and analyzing time-series data, including metrics, logs, and traces. Its stated application areas include monitoring and observability, IoT, and operations analysis. The system uses an MPP architecture with ts-sql, ts-meta, and ts-store components that can be scaled independently. Column-based storage, compression, automatic partitioning, and LSM-based techniques are part of its storage design. A built-in AI analysis platform provides real-time anomaly detection. Query options include InfluxQL, PromQL, and GeminiQL; ingestion methods include InfluxDB Line Protocol, Apache Arrow Flight, and Prometheus remote_write. It also provides HTTP APIs for expression and metadata queries and remote reads and writes. Deployment is supported on Linux, macOS, and Windows, as well as through Docker and Kubernetes. Authentication is disabled by default and must be enabled in configuration. PromQL compatibility covers 90% of Prometheus functions and operators, with some unsupported.