Database migrations are typically one of the biggest challenges when we’re moving applications to the cloud. The reason for it is obvious, databases, or rather their contents, are the lifeblood of many businesses. This makes people rather cautious, when dealing with database migrations. I like that, caution is good. Applications and their servers, on the other hand, can be cloned or rebuild from the scratch. And it’s just fine how you move them, as long as it runs in the end. However, with the database the challenge is, that you need to ensure that every single transaction, and a bit of data is moved, as they were in the source system.
Database migrations, or upgrades, are also complex in the on-premises world and going to the cloud definitely adds a new layer of complexity to it. Having said that, I also feel that too often these complexities are considered too much from the risk perspective, rather than opportunity one.
Now, allow me to explain what I mean by examining 5 typical challenges that can be turned to opportunities.
For the past 10 years or so, I’ve seen it occasionally come up in the discussions that DBA won’t be needed in the future. Originally, it started with the vendors claiming that their database systems are becoming self-tuning. Then the final nail in the coffin was to be the public cloud, which was also to be self-tuning. And it wouldn’t be just self-tuning, it would be infused with AI and tears of the DBAs to produce absolute magic.
While technology has definitely gone forward, nothing’s yet fully self-tuning, but cloud (especially the cloud bills) have certainly brought tears to the eyes of many DBAs, and occasional CFO. There are also signs, that rather clearly, point to the fact that the DBA role, and other IT specialist roles, aren’t dying away anytime soon either.
Public cloud is a really great place to put your application and database workloads. However, it’s not always clear how, exactly, that should happen. Some people talk about migrating, others about modernizing, a few mix everything together, and then there is a bunch of words that all start with the letter R.
In this post, based on my own experience, I’ll attempt to provide a clear differentiation between migration and modernization approaches, and how they map to a mysterious thing called the R-strategies. I will also introduce you to the third option called Midernization, or Moigration. Yeah, I know. The naming is a work-in-progress. Anyway, this is the option that no one recognizes, but almost everyone ends up doing it.
All good things must come to an end, including this 3 part blog post series. In this post, we’ll dive into one of the database systems I am not hugely familiar with, Apache Cassandra, and it’s AWS counterpart, Keyspaces. What is Cassandra, then? It’s an open-source distributed, wide column data store that is capable of providing extreme read and write performance for massive datasets, and delivering scalability and high-availability by forming a cluster from multiple nodes.
Cassandra clusters are also notoriously difficult to manage, with complex scale out and even more complex rollback operations. There are also a bunch of horror stories about the error-prone restoration mechanism, and patching operations of clusters gone horribly wrong. Moreover, it’s lacking a few things, like encryption support, and you do need to learn a new query language (CQL) to make use of it.
Luckily for us, AWS has something for most of the Cassandra pains. Read on, to learn about AWS Keyspaces.
Continuing with the topic of purpose-built database on AWS. This time, I’ll be diving into the wonderful world of Document stores. For a while now, MongoDB has been the gold standard for Document databases. However, as of late, I have come to think AWS DocumentDB as a solid alternative for MongoDB as a document store.
And that is one of the reasons I am focusing on AWS and DocumentDB on this post, it’s an actual purpose-built Document store, rather than a multi-model database, such as CosmosDB. CosmosDB offers a wide variety of APIs to use, Document, Graph, Column and Key-Value, making it a multi-purpose database. The reason I am not touching on DynamoDB is, that the migrations from MongoDB to DocumentDB are much easier.
I have been looking, for various reasons, to purpose-built database space recently. Purpose-built databases, as you can imagine, are databases that are specialized to provide just a single (well, in some cases it’s two) type of data store. Purpose-built databases are also great when you’re building modern, cloud native applications, which has led to the birth of some interesting, fully managed purpose-built database offerings. AWS especially has done a good work on the area, so I figured I’d explore available options there.
Since there’s actually a bunch of these databases available from AWS, I’ve decided to split the post into 3 parts. In the first part, we’ll look into Amazon offering for Redis. Redis is an open-source, in-memory database, that is very popular with the developers. It is also one where AWS is providing us with two alternatives for it. These are Amazon ElasticCache and Amazon MemoryDB.
I spend a lot of my working time and effort to move on-premises databases to the cloud. When I am not doing that, I am most often spending it planning on how to do it more efficiently. While I think today almost everyone agrees with the benefits of going to the cloud, there are a couple of sentences I keep hearing over and over, when we’re planning to move databases to the cloud.
“We haven’t tested it with version X, and can’t guarantee that it works!”
“We only support SQL Server databases running in Virtual Machines”
That, good reader, is the typical sound of a commercial-off-the-shelf (COTS) application making it’s way, kicking and screaming, towards the public cloud. Considering how often I hear these two things been said, it’s easy to end up thinking that public clouds are full of burning wrecks of old applications. However, my own experience from having migrated plenty of SQL Server workloads is, that, about 100% of the time, I don’t have problems with versions or PaaS services (well, except that one time).
In this post, I’ll write about a single feature that can be used as to ensure that your database will be just fine, or even better, and then something about Managed Instances.