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KurrentDB Feature List

March 30, 2025About 5 min

KurrentDB Feature List

Core Features

Event-Native Database

Feature NameDescription
Append-only LogA log where events are only appended and never modified, serving as an immutable audit trail that captures all historical changes within a system.
Immutable EventAll events stored in KurrentDB cannot be altered once appended, ensuring data integrity and simplifying troubleshooting.
Guaranteed WriteWrites are guaranteed to be fully durable once acknowledged.
Guaranteed Consistent Event OrderingEvents are ordered by their append time across both the event log and streams to facilitate operations where the sequence of execution is crucial. Events are guaranteed to be read in the same consistent order whenever they are consumed.
Sequential Event NumberingAn event appended to a stream is automatically assigned a strictly monotonically increasing number (without gap) to ensure reliable state reconstruction and concurrency handling
Stream IndexingEvents in streams are indexed to provide fast access to groups of events in the event log.
Fine Grained StreamEventStore supports billions of streams, allowing granular event organization to efficiently track the lifecycle of every distinct entity within a system.
Optimistic Concurrency ControlConcurrent appends that lead to lost updates can be prevented with optimistic concurrency control. This is done in a lock-free manner, to reduce contention and performance overhead.
Multiple Hosting OptionsKurrentDB is available fully managed with Kurrent Cloud or self-managed on Linux, Windows, macOS, or with Docker

Projection

Feature NameDescription
By Category System ProjectionQuickly retrieve indexed events from streams that share the same category.
By Event Type System ProjectionQuickly retrieve indexed events that share the same event type.
By Correlation ID System ProjectionQuickly retrieve indexed events with the same correlation ID, enabling data lineage and root cause analysis.
User-Defined ProjectionAllows users to define custom projections in javascript to transform or filter events to another stream or a state programatically.

Subscription

Feature NameDescription
Catch-up SubscriptionSelf-managed subscription of filteredĀ events by stream or event type from a particular position or in real-time as events occur.
Persistent SubscriptionServer-managed subscription that supports multiple competing consumers, checkpointing, retries, and parking (i.e.,Ā dead-lettering)

Connector

Feature NameDescription
Connectorv24.10

Fully configurable integration to external systems that can push events from KurrentDB in real-time. Supports at least once delivery, retry, event filtering, event transformation, automatic checkpointing, leases, and high availability.
HTTP Sinkv24.10

Publishes events from KurrentDB to an HTTP endpoint.
Kafka Sinkv24.10License Required

Publishes events from KurrentDB to Kafka topic or partition using a key found in the events. Supports broker acknowledgment and basic authentication.
RabbitMQ Sinkv24.10License Required

Publishes events from KurrentDB to a RabbitMQ exchange. Supports broker acknowledgment and basic authentication over a secured connection.
MongoDB Sinkv24.10License Required

Publishes events from KurrentDB to a MongoDB collection or document. Supports basic authentication.

Clustering

Feature NameDescription
High Availability ClusterEnsures high availability and fault tolerance by using secure, quorum-based replication, leader election via the gossip protocol, and configurable node roles and communication, with each node independently maintaining data without shared disks.
Read-only ReplicaCluster nodes that replicate data asynchronously from the cluster but do not participate in write operations, elections, or quorum. Used primarily to scale read operations.

Interface and SDK

Feature NameDescription
KurrentDB ClientClient SDKs are available in Python, Java, .NET, Node.js, Go, and Rust to use and administer KurrentDB.
gRPC APIProvides an API based on the gRPC protocol for high performance, low latency, and streaming support for all KurrentDB operations
HTTP APIOffers simple and basic RESTful administration of KurrentDB.
TCP APIDeprecated

A deprecated API that provides low-level, high throughput TCP access to KurrentDB. Not supported for releases after 23.10.

User Interface

Feature NameDescription
Admin UIThe web-based KurrentDB user interface that manages events, streams, server configurations, monitoring, etc.
Kurrent NavigatorPreview

The next-generation KurrentDB user interface built as a native desktop application.

Security

Authentication

Feature NameDescription
User name/Password AuthenticationAuthenticate users based on credentials provided.
OAuth AuthenticationLicense Required

Connect to an identity server and authenticate users based on JWT
LDAP AuthenticationLicense Required

Authenticate users against LDAP-based directory services.
User X.509 Certificatesv24.10License Required

Support user-based X.509 certificates for authentication.

Authorization

Feature NameDescription
User ManagementCreate, update, and assign users to pre-defined user groups.
Stream Access Control ListDefine which users or groups can read, write, or delete on a stream level.
Stream Access Policyv24.10License Required

Define access policies to control who can read, write, or delete streams for multiple streams using stream rules.

Encryption

Feature NameDescription
Encryption at restv24.10License Required

Secure events stored on disk using file-level encryption.
Encryption in transitUse TLS to secure data during network transmission.
Kurrent Certificate Generation ToolThe command line interface that eases the generation of a certificate authority and node certificates for encryption in transit.
FIPS 140-2License Required

Compliance with FIPS 140-2 standards for cryptographic modules.

Operations

Configuration

Feature NameDescription
Multiple Configuration OptionsConfigure KurrentDB through YAML, environment variables, or the command line

Data Cleanup and Housekeeping

Feature NameDescription
Stream Truncate and DeletionTruncate streams by max age, max count, or before a particular position or delete an entire stream.
ScavengingManually reclaim disk space for compliance or storage purposes by completely removing truncated and deleted streams from disk.
Auto-scavengingv24.10License Required

Automatically schedule and coordinate scavenging for a cluster in a way that minimizes performance impact.

Monitoring

Feature NameDescription
LoggingProvides detailed logs for server operations to console and log files.
Logs Endpointv24.10

View or download logs over HTTP for authenticated KurrentDB users without needing file system access.
MetricsCollect KurrentDB metrics such as CPU, memory, disk usage, and the status of projections, subscriptions, elections, etc.
Metrics with PrometheusAllow systems to scrape metrics in Prometheus format for monitoring over an HTTP endpoint.
Metrics with OpenTelemetry Exporterv24.10License Required

Export and push metrics to an endpoint via the OpenTelemetry protocol.

Backup, Replication, and Migration

Feature NameDescription
Backup and RestoreProvide functionality for full or differential backups and restores over disk snapshots or file copy backups.
Kurrent ReplicatorFacilitate replication or migration of data between different KurrentDB clusters or instances.

Administrative Tool

Feature NameDescription
Kurrent CLICommand line tool for administrative operations on KurrentDB such as scavenge, backup, restore, merge index, delete stream, as well as user and projection management.

Next Steps

Contributors

Paulo Borges
Last Updated: