Apache Ignite vs etcd

Apache Ignite is a free, open-source, memory-first distributed SQL database for high-velocity workloads. It keeps data primarily in memory, with persistence available through AIPERSIST, and supports ACID transactions across partitions using Raft consensus. MVCC snapshot isolation enables non-blocking reads. SQL access includes JDBC drivers, a Table API and native APIs, while catalog-driven schema management allows column and index changes without stopping the cluster. DataStreamer handles high-throughput writes with backpressure control. Native clients are listed for Java, .NET, C++ and Python, alongside AWS, Azure, GCE and Spring extensions. Built-in operational capabilities include authentication, SSL/TLS security, OpenTelemetry metrics, recovery snapshots and backups. Listed uses include event stream processing, microservices state management, session management and AI/ML feature stores. Ignite is self-hosted and available through binary, source, Docker and Maven/Gradle options. The project identifies Ignite 2 as a long-term-support release recommended for existing deployments.

etcd is an open-source, strongly consistent distributed key-value store for data used by distributed systems and clusters of machines. It arranges values in hierarchical directories and lets clients watch keys or directories for changes. Clients can read and write values with standard HTTP tools such as curl, and keys may have optional time-to-live expiration. The project uses the Raft protocol and handles leader elections during network partitions, including when a leader machine fails. etcd is a core Kubernetes component and its primary datastore. The project provides pre-built binaries, source builds, and container images. Linux on AMD64 and ARM64 is tier 1; Darwin and Windows on either architecture are tier 3, and other platforms are unsupported. TLS and client-certificate authentication are supported for client and peer connections, but neither is enabled by default. The software is self-hosted and licensed under Apache 2.0, with a listed price of free. The integrations listing includes Kubernetes, CoreDNS, and language client libraries, while warning that third-party tools and libraries there are not tested or maintained by the etcd team.