Branded as Microsoft’s “planetary scale database,” Cosmos DB is one in every of Azure’s foundational companies, powering its personal functions in addition to yours. Designed for distributed utility improvement, Cosmos DB gives a spread of consistency fashions and, extra apparently, a sequence of various personalities that let you use it like several one in every of a set of acquainted databases.
These embody a PostgreSQL-compatible API, a graph database like Neo4j, and its personal doc database mannequin, in addition to assist for the acquainted Apache Cassandra distributed database. One of many extra in style personalities is a set of APIs that purpose to supply a lot of the options of the favored MongoDB NoSQL database. This final possibility is an fascinating one, because it means that you can shortly take current on-premises trendy functions and shortly convey them to the cloud, prepared for re-architecting on a world scale.
Understanding Request Models billing prices in Cosmos DB
There’s one challenge that usually confuses builders coming from a extra conventional improvement setting: Cosmos DB uses the concept of Request Units to handle billing, along with Azure’s normal storage costs.
An RU is a approach of describing and charging for the way a database like Cosmos DB makes use of Azure sources. It brings collectively compute, I/O and reminiscence, utilizing the sources to make a 1KB learn of a single merchandise as the bottom of what can greatest be considered Cosmos DB’s personal inner foreign money.
With a single learn of a single merchandise measured as 1 RU, all different operations are billed in an analogous approach, bundling their actions and useful resource utilization as a price in RU. You buy bundles of RU which might be then spent in database operations, very similar to shopping for tokens for a sport like Roblox. RU can be utilized to handle operations, with a set quantity per second accessible in your operations or used to pay for serverless operations. It’s also possible to use RUs to permit your database to scale as wanted, although this does imply a very busy utility can instantly turn into very costly to run.
The RU mannequin, whereas logical for a cloud-native service, makes it laborious so that you can predict the price of operating Cosmos DB if you happen to’re used to conventional costing fashions. Whereas it’s potential to construct instruments to assist predict prices, you need to account for extra than simply the operations your database makes use of, as the kind of consistency mannequin you select will have an effect on the accessible throughput.
Introducing vCores to Cosmos DB
Microsoft is now providing an alternative to the RU model for developers bringing their MongoDB-based applications to Cosmos DB. As a substitute of paying for RUs and storage, now you can select to give attention to the extra acquainted mixture of utility situations and assigned disks. This provides you entry to a mannequin that’s lots nearer to MongoDB’s managed Atlas cloud service, permitting a extra predictable migration from on premises or different clouds.
Out there as Azure Cosmos DB for MongoDB vCore, this new launch of Microsoft’s NoSQL database is a full-fledged a part of your Azure infrastructure that offers you automated sharding and integration with Azure’s Command-Line Interface and different administration tooling.
Microsoft describes it as a strategy to “modernize MongoDB with a well-recognized structure.” The purpose is to ship as shut as potential a set of suitable APIs, whereas nonetheless providing scalability. For instance, Microsoft instructed us,
“Azure Cosmos DB for MongoDB vCore permits richer, extra complicated database queries such because the full-text searches that energy cloud-based chatbots.”
Transferring functions from MongoDB to Cosmos DB
If in case you have code utilizing MongoDB’s question language to work together with your information, it ought to work as earlier than, with the principle requirement being to vary any endpoints to the suitable Azure handle.
Nevertheless, not all instructions can be found on Cosmos DB, because the underlying options don’t map between the 2 databases. It’s value taking note of the listing of supported instructions, particularly if you happen to’re counting on MongoDB’s session management tooling, as a lot of this isn’t at the moment accessible in Cosmos DB. You’ll even have to modify any authentication to Azure’s native tooling.
Moving data between the two should be easy enough, as MongoDB’s export and import instruments let you save information as both JSON for partial exports or the extra compact BSON for a full database. In the event you’re shifting loads of information as JSON, this may be costly, as you’ll be charged for information transfers.
Pricing is based on standard Azure virtual infrastructure, utilizing both excessive availability or decrease availability techniques. In the event you don’t want an HA system, then it can save you as much as 50% on the HA pricing. Base storage for a vCore Cosmos DB system is 128GB, which must be appropriate for a lot of widespread workloads. You possibly can select to start out with two vCPUs and 8GB of RAM and scale as much as 32 with 128GB of RAM.
Whereas most functions will work with little modification, just like the RU model, the vCore launch of Cosmos DB’s MongoDB assist does have some variations from the official APIs. We requested Microsoft if there have been plans so as to add extra protection in future releases, past the shift to vCore over serverless.
“In most situations, this makes the 2 applied sciences totally suitable. Based mostly on buyer suggestions, one of many bigger ache factors concerning compatibility between MongoDB and Azure Cosmos DB was the necessity to re-engineer and reshape their MongoDB databases to suit with how Azure Cosmos DB is architected. This launch eliminates that ache level as the 2 databases are actually basically the identical ‘form.’ As well as, we’ve robust function compatibility between the 2 and can proceed to roll out extra options as this strikes out of preview and into basic availability,” a spokesperson responded.
This new MongoDB possibility ought to make it simpler to convey a MongoDB workload you’ve already written to Cosmos DB and thereby free your self from having to run your personal MongoDB infrastructure — or allow you to consolidate on utilizing Cosmos DB as your cloud database, bringing databases from different cloud suppliers to Azure, the place you need to use all the opposite Azure sources and companies that smaller suppliers like MongoDB don’t provide.