Are you able to use an in-memory Database? - (r)

Oct 29, 2022

Writing data to databases adds delay because databases typically write data to a disk instead of keeping the information in memory. It's common for databases to apply compression and encryption to reduce latency while writing and reading data. In order to overcome this issue it is possible to use an in-memory database for fast retrieval of data and storage in RAM instead of a disk.

This article explains the way in-memory databases function, some popular options, and some of the trade-offs versus a standard database.

What Are In-Memory Databases?

Low latency is costs because the information saved in memory can be lost if a server malfunctions. In contrast to disk storage, memory doesn't retain its contents upon power failure, therefore it's a matter of the ability to withstand power loss in comparison to speed.

Reducing latency is particularly important for websites. Customers who feel that the site is responsive are more likely to remain on the site. Furthermore, Google and other search engines additionally consider site speed as an element when it comes to SEO. Speedy websites are more prominent in search results, increasing your chances of having users visit your site.

Understanding Databases in Memory

Because in-memory databases store data inside RAM. They have far lower latency than an HDD, which uses moving and mechanical components to access the correct storage position. The HDD is then required to read information and then transfer it through the connection with the storage device and the computer. Moreover, even with SSDs, RAM is still at least 30 times more efficient because of its more performant memory chips and CPU interface. Certain benchmarking tests have demonstrated that the use of MySQL coupled with Redis -- which is a well-known memory-based database -- as an caching layer could reduce the time to query by as much as 25% when compared to a standalone MySQL database.

A graph representing the number of requests with only MySQL and with both MySQL Redis.
Benchmarks using only MySQL or with MySQL as well as Redis. (Image Source: DZone)

The second reason is why the in-memory database is faster than. There is the possibility to optimize the data structures used by in-memory databases for speedier retrieval. For example that relational databases typically employ B-trees for indexes which allow for rapid searches, while also supporting reading and writing large data blocks to disk. In-memory databases aren't required to transfer data blocks to disk , and they can select better data structures that are more efficient and reduce the latency. These databases typically store and use data as-is, without any transformation or parsing on the layer that is called the database. This can also lead to a decrease in latency as it improves the time to read and write.

In-memory databases have become more sought-after due to advancements in technology. In the first place, the cost for a gigabyte (GB) of RAM has decreased significantly over the last 20 years and has helped make using memory for data storage less expensive. The advancements in database software in memory and cloud-based managed services have also helped ease many of their major drawbacks.

Benefits and disadvantages of in-memory Databases

The most significant benefits of using in-memory databases is:

  • They are easier to scale due of how they store information.
  • They can increase the reliability of the application.

The majority of databases in memory keep data unstructured or semi-structured instead of storage in complicated relational models. Unstructured data makes scaling the database more straightforward, as the network burden of data transfer when joining data that lives on many nodes is not necessary.

The major drawbacks to the in-memory database are:

  • Increase in cost if used as the sole database
  • Limited storage size
  • Security features are less robust.

The databases that are in memory generally do not have security features such as encryption since everything needs to be stored in memory -- including encryption keys. This makes encryption useless since any entity with access to the memory could, theoretically have access to keys to encryption.

In-memory databases are a great way to cut costs when combined with conventional databases. But they're typically more expensive when they are used solely as a database, particularly if they're used to store large amounts of data, because of the cost of memory as compared to disk storage. It also limits the volume of data you can keep, since storing huge files in memory can be costly and usually requires several servers.

Why can't all Databases in-memory?

The main drawback preventing in-memory databases from being ubiquitous is cost. While prices for RAM have dropped substantially, they're larger per GB as HDDs as well as SSDs. This cost makes in-memory databases prohibitive for applications with colossal data footprints.

If the cost of RAM continues to fall it could come to the time that in-memory databases are the default, and disk-based databases are only employed in certain niche situations.

Use Cases of In-Memory Databases

The most popular uses for in-memory databases is caching. The memory-based database to serve as a cache layer when used in conjunction with the traditional database. The in-memory database stores frequently accessed data, preventing repeated and expensive searches in the disk-based database , and offering users with a more efficient users' experience.

These databases are also well-known for ecommerce websites as well as forums and blogs with comment sections. It is due to the fact that they are extremely dynamic websites. Online stores want to tailor the user experience and show real-time product availability. Blogs and forums can have thousands or hundreds of users simultaneously posting and commenting. The site has to be able to cope with at a very high speed of write and be able to serve current content and feedback and feed them back quickly. In-memory databases reduce the latency in storing user-generated content and giving users a personalized and up-to-date user experience.

Databases in memory are ideal to create game leaderboards. They can update and retrieve data at a rapid pace and quickly filter data for an up-to-date view of the leaderboard as the game progresses.

Exemples of Databases in Memory

Sites that use caching by default. Websites that have frequent database requests will still significantly benefit from Redis. Database latency is one of the major reasons that slow websites down. Redis helps reduce this burden and enables the website to grow quickly.

Summary

The latency of databases can greatly impact an application's or website's time to. Reading from and writing to hard disks increase the latency. Memory-based databases decrease latency in databases since they save data in memory. Although they use SSDs they are faster because it uses speedier memory chips as well as a more efficient interface to the processor. Additionally, it is possible to optimize the structures of data that are used by databases in memory to make it faster for search.

Memory databases can improve the speed of websites and applications by acting as a caching layer between the website and a traditional database. Memory is faster to access than disks, and this reduced overhead leads to faster loading times, and may contribute to improved SEO.

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