In the world of high-performance, modern software engineering, developers often face a tough tradeoff: how to achieve lightning-fast data retrieval response rates without adding complexity, sacrificing reliability, or getting locked into specialized, external data caching products or platforms. What if you could harness the power and flexibility of your existing Postgres database to solve this challenge? Enter the Microsoft.Extensions.Caching.Postgres library, a new nuget.org package that brings distributed caching to Postgres, unlocking speed, simplicity, and seamless integration for modern .NET workloads.

In this article, we’re going to take a closer look at the Postgres caching store, which introduces a new option for .NET developers planning on implementing a distributed cache, such as HybridCache, paired together with a Postgres database to provide distributed backplane operations.

One data platform for multiple workloads

Postgres’ reputation for reliability, extensibility, and standards compliance has long been respected, with Postgres databases driving some of today’s largest and most popular platforms.  Increasingly developers, data engineers, and entrepreneurs alike all rallying to apply these benefits. One of the most compelling aspects of Postgres is its adaptability: it’s a data platform that can simultaneously handle everything from transactional workloads to analytical queries, JSON documents to geospatial data, and even time-series and vectorized AI search. In an era of specialized services, Postgres is proving that one platform can do it all and do it well.

Intrepid engineers have also discovered that Postgres is often just as proficient in handling workloads traditionally supported by other very different technology solutions, such as lake-house, pub-sub, message queues, job schedulers, and session store caches. These roles are all now being powered by Postgres databases, while Postgres simultaneously continues to deliver the same scalable, battle-tested, and mission-critical ACID-compliant core relational database operations we’ve all come to expect.

When speed matters most

Database-backed cache stores are by no means a new concept; the first version of a database cache library for .NET was made available to developers exploring the nuget.org ecosystem (Microsoft.Extensions.Caching.SqlServer) in June 2016. This library included several impressive features, such as expiration policies, serialization, and dependency injection, making it ideal for multi-instance applications requiring shared cache functionality. It was especially useful in environments where Redis or other cache providers were not available. 

The convenience of leveraging a transactional database’s usefulness to function as a distributed cache comes with some tradeoffs, especially when compared against services such as Redis or Memcached; in a word: speed. All the features which make your database data durable, reliable, and consistent require precious additional clock cycles and I/O operations, and this “overhead” resulted in performance costs when compared to the alternative memory stores and caching system options.

What if it was possible to maintain all those familiar and convenient interfaces for connecting to your database, while simultaneously being able to precisely configure specific tables to throw off the burden of crash consistency and replication logging? What if, for only the tables we selected, we could trade this durability for pure speed? Enter Postgres’ UNLOGGED Tables.

Postgres' adaptable performance

Another compelling aspect of Postgres databases is the ability to significantly speed up write-performance by bypassing the Write Ahead Log (WAL). The WAL is designed to ensure that data is crash-consistent (and replicable), and writing to your database is comprised of a transparent two-step process:

1. your data is written to your database tables, and
2. these changes are also committed to a separate file to guarantee the data’s persistence.

It also happens that in some circumstances, the tradeoff to increase performance can be worth the sacrifice to crash-consistency, especially for short-lived, temporary types of data, like when used as a cache store. This table configuration is scoped to individual tables, which allows for combinations of “logged” and “unlogged” table configurations, both operating side-by-side within the same database instance. The net result: Postgres can provide incredibly performant response times when used as a distributed cache, rivaling the performance of other popular cache stores, while also providing the simplicity, familiarity, and consistency that the Postgres engine naturally offers. 

HybridCache for your .NET solutions

It was this capability*combined  with the inspiration from the SQL Server library that inspired the creation of the nuget.org  Microsoft.Extensions.Caching.Postgres package. As a longtime .NET developer, I have personally witnessed the incredible evolution of the .NET platform and the amazing growth, enhancements, and improvements to the languages, the tooling, runtimes, and the incredible people behind each of these contributions. The recent addition of HybridCache is especially exciting to consider incorporating into your .NET solutions because it dramatically simplifies the steps required to add caching into your project, while simultaneously linking in-memory cache with a second-level tiered cache service. This seamless integration provides your application with the best of both worlds: blazing fast in-memory retrieval paired with a resilient fail-safe and similarly performant backplane in the event an application instance blinks, scales up/out, etc. 

Don’t just take my word for it, let’s look at some of the benchmarks between a Redis cache and Postgres database. The tests are comprised of synchronous and async operations across three different sized payloads (128, 1024, and 10240 bytes) for read/write, containing both single and concurrent messages, and at fixed and random positions. The tests are further divided into two types of cache expiration windows: absolute/non-sliding and sliding/relative windows. Consider the output from a suite of benchmarks tests, keeping in mind these results are based on microseconds, meaning 1,000 microseconds equals 1 millisecond:

What do these results reveal? In certain respects, there aren’t that many surprises. Bespoke memory-based key-value cache systems like Redis continue to outperform relational databases in terms of pure speed and low latency. What is really exciting to see is that Postgres comes very close to Redis performance for more intensive operations!

Finding the right fit for your solution

I’m excited to make this Postgres package available to everyone considering distributed caching in their solution designs. The combination of HybridCache paired with your choice of backplane will allow you to select the right technologies and tools that are best suited for your solution. Our GitHub repo also contains a variety of sample applications, which demonstrate how to configure and use HybridCache together with the Postgres distributed cache library within a Console app service, as well as an Aspire-based sample Web API. I encourage you to explore these examples and share your thoughts and ideas. I look forward to any feedback you may have to share about the Microsoft.Extensions.Caching.Postgres package. Keep advancing, keep improving, and keep contributing to be a “builder” and an active part of our incredible community!

* This package extension is highly configurable, and you can choose whether to enable/disable bypassing the WAL for your cache table, along with several other options that can be adjusted for your particular use case.