February 2018 Summaries

Redis 4.0 introduced Modules, a significant shift in the Redis ecosystem, but also brought an important new command called UNLINK, which provides a game-changing solution for deleting large keys without tying up the entire server. Until now, deleting large keys with DEL could take a long time due to single-threadedness and memory deallocation, but UNLINK removes the key from the keyspace in one thread and starts reclaiming memory in another, resulting in much faster performance, especially for big values. While there are some edge cases where DEL might be preferred, UNLINK is generally recommended as it provides more consistent behavior and better overall performance with only a small code change required to replace existing DEL commands with UNLINKs.

Containers are lightweight, stand-alone, portable, self-contained software execution environments that have their own CPU, memory, I/O, and networking resources but share the kernel of the host operating system, utilizing linux namespaces and cgroups to create resource isolation. Containers offer low startup overhead compared to virtual machines running on a hypervisor, making them an attractive option for development and software packaging. Kubernetes is a popular open-source container orchestration engine that provides self-healing, scaling, scheduling, and rolling updates of containerized applications. Redis Enterprise offers a high-performance, low-latency in-memory NoSQL solution with data persistence, automatic failovers, backups, and replication across datacenters, and its Kubernetes service enables easy deployment and management on a cluster.

Redis has a unique history, starting as a cloud service for Redis and Memcached, with the development of robust automation techniques that attracted many users. The software's availability was expanded to include downloadable versions for on-premises use, and critical features were added to broaden its appeal. The technology underpinning the service was unified under the name Redis Enterprise, which encompasses all deployment options, including public clouds, VPCs, and software installations. This unification aims to simplify customer choice and provide a clearer understanding of the company's secret sauce technology. The Redis Enterprise Cloud offers fully-managed service in cloud regions of choice, while the Redis Enterprise VPC provides a secure, private cloud service within VPCs. The Redis Enterprise software can be deployed in various operating environments, including Linux, MacOS, Windows, and Docker containers.

We built a back-end database of sharing stations and indexed it with location information using Redis' geospatial data structure. We determined the user's current location through built-in services provided by the operating system, such as CoreLocation on Apple devices. Using the geospatial functions of Redis, we can look up stations within a given distance of our current coordinates, allowing users to find nearby bike-sharing stations and choose a location for their trip. Additionally, Redis provides several other query commands, including GEOPOS, GEODIST, and GEORADIUSBYMEMBER, which can be used to further enhance the location-aware features of an application. These geospatial indexing functions make it easy for developers to add location functionality to their applications.