BTrDB vs GreptimeDB

BTrDB is a free, MIT-licensed, self-hosted time-series database for dense, high-precision univariate data. It partitions data by time, supports clustered deployments, and records stream changes as new versions that queries can target. Streams have unique UUIDs and can be grouped into collections with tags and annotations. The Python btrdb package supports nanosecond-timestamp queries and insertion through Stream.insert, PyArrow tables, or pandas DataFrames. Statistical queries can return minimum, maximum, mean, count, and standard deviation without reading every underlying point. StreamSets can be filtered and converted to pandas DataFrames or CSV files. Documentation shows Dash and Plotly visualization, Ray-worker serialization, TLS on port 4411, and API-key authentication requiring that TLS port. Arrow-based tabular methods are documented for commercial customers with Arrow-enabled servers. BTrDB reports measured cluster throughput and compression figures, and describes smart-grid aggregation at city or country scale as one target use case.

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.