Do you need an elastic database?

Not every company or application needs an elastic database. Some applications can get by just fine on a single database server, rendering database elasticity moot from their perspective. To make this determination, simply ask yourself:

1. Will I need more than a single database server?

Look at your current load and your projected growth and ask yourself whether it will exceed the capacity of a single server. If it doesn’t now, nor will it in the future, then you don’t need an elastic database.

2. Will my load fluctuate sufficiently to warrant the investment in elasticity?

If your database requirements won’t experience fluctuations in demand—e.g. daily, weekly, monthly, seasonal changes in the number of servers required—then elasticity isn’t important. For example, if you have a social networking application that requires 2 database nodes 24x7, but peaks at 10 nodes for 2 hours a night, then elasticity is important. If your database has a steady load that requires 3 database nodes and that load doesn’t change, then elasticity isn’t important.

3. Will my database load grow with time?

I your database load will grow with time, then you need to evaluate the growth pattern and ask yourself whether you can handle this expansion manually, or if you simply want to rely on an elastic database to grow seamlessly.

If your answer to these three questions is no, then you don’t really need an elastic database. Now there are certainly other reasons to consider ScaleDB (e.g. high-availability, eliminate partitioning/sharding, eliminate master-slave issues, etc.) but elasticity may not be one of them.

Cloud Elasticity & Databases

The primary reasons people are moving to the public cloud are: (1) replace capital expenses with operating expenses (pay as you go); (2) use shared resources for processes like back-up, maintenance, networking (shared expenses); (3) use shared infrastructure that enables you to pay only for those resources you actually use, instead of consuming your maximum load resources at all times (pay-per-use). The first thing you’ll notice is that all 3 cloud benefits have their basis in finances or the cloud business model.

We will focus in on #3 above: Pay-Per-Use. The old school model was to build your compute infrastructure for the maximum load today, plus growth over the life-cycle of the equipment, plus some buffer so the systems don’t get overloaded from spikes in usage. The net result is that your average usage might run 10% of the potential for the infrastructure you mortgaged your home to buy. In other words, you were paying 10X more than you would pay if you only paid by usage. In reality, you might pay half as much to run on the cloud, with the balance of the savings going to the cloud company in the form of profits. This works and it is a win-win for both you and the public cloud.

To achieve this Pay-Per-Use ideal, and the compelling financial advantages it enables, the infrastructure must scale elastically. You must be able to add compute power seamlessly and on the fly, without shut-down. How important is this elasticity? Amazon named their service “EC2” for “Elastic Cloud Computing”. Elastic is the first word, I would say it is pretty important. Besides, if the cloud weren’t elastic, you would simply be paying for the same computer costs, plus the public cloud company’s markup for expenses and profit.

So how elastic are public clouds? The entire cloud stack is elastic, except for one piece, the SQL database. Cloud companies recognized that the SQL database was the Achilles heel of cloud elasticity. To address this problem, they created NoSQL, which delivers database-like capabilities, but removes the things that make a SQL database inelastic; namely SQL, ACID-compliance, data consistency, transactions, etc.

NewSQL appears to be the response from the database vendors, who believe that there is a market for SQL databases that provide cloud elasticity. Not all NewSQL solutions address elasticity, but a few of us do. In my next blog post, I’ll address whether or not database elasticity is important…hint: it depends upon your needs.