There are a few factors to consider when choosing a database — a primary aspect is its cost, but flexibility and support from hosting providers are also crucial.

An open source database is your best bet for many reasons.
For starters, an open source database will be 100% available to you regarding the codebase and potential of the system. In contrast, a fully closed proprietary solution will not offer the same level of depth or flexibility unless the developer chooses to enable it.

The following list contains some open source databases, but it’s not exhaustive. There will be many more options than we could ever include here, so we’ve curated our top picks.

Our first entry is arguably the most prominent go-to option for an open source database, so let’s start there.

1. MySQL

You don’t need to know a lot about SQL to use MySQL, and the learning curve isn’t steep. You can work with the database from the command line, and MySQL has high compatibility with almost every operating system (OS) you’ll use.

On the whole, MySQL is great for most use cases, as it’s a solid, quick, and dependable jack-of-all-trades. Because of this and its positioning relative to other solutions over the years, most hosts will support MySQL databases. However, there are a few drawbacks to consider too:

• While MySQL is efficient in most cases, it can be slower for large database sizes.
• What’s more, its debugging tools could improve compared to other (even proprietary) solutions.
• There are instances of data corruption, although it’s not a severe issue.

It’s hard to name too many negatives because, on the whole, MySQL is a solid and dependable database that suits most applications. However, some users look into other products for reasons we’ll get into next.

2. MariaDB

MariaDB is a fork of MySQL, hence, the compatibility is almost 1:1. The developers of MariaDB also like to keep compatibility close to its fork. As such, you can use MariaDB as a “drop-in” replacement for MySQL with almost no consequence and migrate to it without fuss.

Although, despite being a fork of MySQL, MariaDB still looks to forge its path. There are a few unique features of the open source database that you should know:

• MariaDB uses the Aria storage engine to handle complex SQL queries. This gives the database a speed boost over MySQL.
• You can use dynamic rows for table columns, which helps flexibility and adaptability.
• There are some specialized storage engines for specific use cases that you won’t find in MySQL. For example, you can implement distributed storage, distributed transactions, and much more.

Because of the close compatibility, you can use MariaDB wherever you use MySQL without much penalty. As such, you can consider it “all things to all apps,” much like its fork. However, it’s worth noting that the compatibility is only one way, so you’ll need to choose a side: MySQL or MariaDB. This open source database commands loyalty!

3. PostgreSQL

If all you know is PHP and WordPress, you probably don’t know much about PostgreSQL. However, it’s a relational, open source database that many developers use in data science, graphing, and AI industries because it’s ideal for Python and Ruby applications (although you could use PHP too).

Compared to MySQL’s robust denim, PostgreSQL is more like fine silk in that it’s a thoughtful, open source database that provides many killer features:

• You can implement asynchronous replication.
• There’s native support for JSON-style document storage, key-value storage, and XML.
• You can carry out full-text searches of your database.
• Several built-in data types will be invaluable to some applications, such as geolocation, arrays, and ranges.

Even so, you’ll want to handle PostgreSQL with care, as it’s not as adept as other solutions for read-heavy applications. For one thing, if you have to create reports from existing data regularly, PostgreSQLs document storage could suffer from such a large dataset.

4. Redis

Redis is different from the rest of the open source databases on this list, as you don’t use it for almost any of the same applications.

It’s a database that enables you to structure data as key-value pairs. You’ll find this is similar to associative arrays in PHP or dictionaries in Python — it’s a way to link data to reference it at speed later:

<?php
$type = array("Charmander"=>"fiery", "Squirtle"=>"soggy", "Snorlax"=>"sleepy");
echo "Snorlax is " . $type['Snorlax'] . " all the time.";
?>

“Speed” is the crucial term here because Redis is a go-to database for caching. There are a few reasons for this:

• Redis is an “in-memory” storage solution — entirely in RAM — which means the read-write speeds are blazingly fast.
• You can learn the basics of Redis within a few minutes and begin to store objects straight away.
• You’re able to set expiry times to strings, which is a critical component of caching.
• A novel Pub/Sub feature uses Redis as a buffer for messages between a sender and receiver. Instead of these endpoints making a direct connection, a sender will post to a dedicated Redis “channel,” which then moves it onto the receiver (and vice versa).

5. SQLite

For this relational open source database, the clue to the key selling point is in the name: SQLite is a tiny, lightweight library that offers a database engine.

You’ll often find it in smaller devices such as smartphones because it’s lightweight. In fact, the whole database consists of one .sqlite file that can live anywhere on your system. You won’t need to install any server software or connect to other services to use SQLite.

Despite the database being such a lightweight tool, you can still have a database size in the hundreds of terabytes, with a gigabyte maximum row size. Even with file sizes this large, SQLite remains fast.

You’ll find that there are a lot of good use cases for using SQLite as your database:

• Developers of simple apps will like SQLite because it’s a no-nonsense, direct solution.
• It’s great for Internet of Things (IoT) applications where there won’t (or can’t) be a sysadmin or developer on hand.
• SQLite can be suitable for low-traffic websites because those needs will be straightforward.
• Although we’re mainly discussing web apps here, desktop apps could also use SQLite to keep performance high.

Given the structure of SQLite, it’s not going to work as well for large-traffic sites as performance won’t be optimal. What’s more, a few features are missing from this lighter open source database that could be important.

For example, you cannot query the database with a client like MySQL or MariaDB.

Summary

If you want to create an app of any kind, a database is necessary. Web apps need at least one database — you may need several to contain all of the data you process across various use cases.

While there are lots of databases with various license types, an open-source database is going to be your best bet for most cases.

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