Apache IoTDB vs GreptimeDB

Apache IoTDB is an open-source industrial IoT time-series database for collecting, storing, managing, and analyzing device data across edge and cloud deployments. The project describes high-speed writes for millions of networked devices alongside fast reads. Query features include aligning time across devices and sensors, time-series computation, and aggregation by time dimensions. Ingestion options include IoTDB-SQL, JDBC, Java, C++, Python, and Go native APIs, REST, MQTT, CSV, and TsFile. Named analysis ecosystem examples include Hadoop, Spark, Flink, and Grafana. Deployment options include cloud installation, a desktop terminal tool, and synchronization between cloud and on-premise machines. The REST service is disabled by default and uses Basic Authentication except for the health check endpoint. Data and cluster permissions can be managed through users, roles, and privileges. The homepage states disk storage can cost less than $0.23 per GB. The project lists energy, aerospace, transportation, steel, and other IoT scenarios. Its JDBC documentation cautions that insert operations may not provide high-performance writing and recommends the Java Native API for Java applications.

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.