Yes they are sharing the same Database. Regardless of the fact that you micro-service is deployed to multiple instances or one instance the deployment instances of your micro-service are accessing and using your one database which belongs to that micro-service. All your instances of your micro-service should access the same database.
Can multiple microservices connect to same database?
Yes, it's possible to integrate a database for microservices. You can create a single shared database with each service accessing data using local ACID transactions.
Does each microservice need its own database?
As you described it very well above, each microservice needs to own it's DATA, which could be held within a dedicated database, within a dedicated schema (within a database), or even a set of dedicated tables (within a schema within a database).
Can two microservices talk to each other?
There are two basic messaging patterns that microservices can use to communicate with other microservices. Synchronous communication. In this pattern, a service calls an API that another service exposes, using a protocol such as HTTP or gRPC.
Is it a good idea for microservices to share a common database?
I've seen folks refer to this idea in part, trivially, as “each microservice should own and control its own database and no two services should share a database.” The idea is sound: don't share a single database across services because then you run into conflicts like competing read/write patterns, data-model conflicts ...
Why do microservices need a separate database?
Each microservice should have its own database and should contain data relevant to that microservice itself. This will allow you to deploy individual services independently. Individual teams can now own the databases for the corresponding microservice.
How do I manage multiple databases in microservices?
Create a single database for different microservices is anti-pattern, then the correct way is to create a database for each microservice.
How do I connect two microservices?
The synchronous call is the simplest way to communicate two services. It also bonds them together, since the calling microservice needs to wait for a response from remote. This kind of coupling can sometimes be prevented by using asynchronous communication.
What is the way to share data between microservices?
Using messaging to exchange lightweight data structures, often via a message broker that manages sessions and data queues. Via a shared data store, where the service might not communicate directly, but share a common source of information. Exchanging RESTful data, similar to the way they communicate with clients.
Can microservice call other microservices?
One microservice can easily expose a REST endpoint for other microservices to call it. Integration via RESTful endpoints is typically implemented when a microservice needs to call another and receive an immediate (synchronous) response.
Can microservices have single database?
Even if microservices share a database, it is possible to configure a single database so that tables are separated by clearly defined, logical boundaries and owned by specific services.
Does database for each service in a microservice is independent?
Loose coupling is the core characteristic of a microservices architecture, because each individual microservice can independently store and retrieve information from its own data store.
How do you scale a database in microservices?
So in order to improve scalability when storing and accessing large volumes of data in microservices architectures, we should divide a databases into a set of horizontal partitions or shards. Each shard has the same schema, but holds its own distinct subset of the data.
Does each microservice have its own server?
Microservices are decentralized and run on different servers, but they still work together for an application. Ideally, each microservice serves a single function, which enables simple routing between services with API communication.
Should each microservice have its own API?
The API is necessary for the microservice architecture to function because the API is the communication tool between its services. Without an API, there would be a lot of disconnected microservices. Technically, the microservice would just build to be a monolith again.
What are the preferred database by Microservice architecture?
Now, there are very good reasons to pick other types of databases—either NewSQL or NoSQL for many microservices. However, abandoning your current relational database all at once is often a foolhardy decision.
How do microservices communicate with each other?
The most common type is single-receiver communication with a synchronous protocol like HTTP/HTTPS when invoking a regular Web API HTTP service. Microservices also typically use messaging protocols for asynchronous communication between microservices.
Why are microservices not beneficial?
This is because you are effectively tightly coupling the services. If a database table changes all the services will have to change .
Why use microservices architecture?
You have to understand that the whole reason for a Microservices architecture is to reduce dependencies between development teams and allow them to move ahead independently with fast releases.
Is it ok to share a physical DB?
Some commenters pointed out that sharing a physical DB may be ok, for example by using separate tables or schemas for different services in the same DB. This is of course possible and still a useful separation of concerns for the service development. It is an architectural (and also organizational-) decision if you want the service teams being responsible for the whole service stack and deployment, including infrastructure, or if you want to separate that out into an infrastructure- or devops-team. Each approach can have its pros and cons depending on your organizational circumstances, scale, requirements, etc.
Can CustomerShippingDetails and CustomerShoppingCheckout share a database?
Not having too many details about your system I would go with a mixed approach. That is, having a shared database for services that take care of similar business logic. So CustomerShippingDetails and CustomerShoppingCheckout can share a database. But a StoreItemsDetails would have a separate database.
Is a DB a service?
Another aspect is that newer, scalable DB technologies are becoming more popular. They generally abstract storage and compute for separate scalability and are used as a service (for example Snowflake, Teradata, BigQuery, etc.). They allow growing to very large sizes with millions of tables and petabytes of content using a single cluster. With those it would be the goal to have the microservice implementation teams not worry about the details of running a DB infrastructure, but just use the DB cluster endpoint as a service dependency. And it would be the normal case to have many services depend on that same DB cluster. However you would still want to pay attention to storage separation, e.g. separate logical tables, collections, or whatever makes sense in the specific DB technology.
Why is sharing schemas amongst two microservices bad?
Sharing a database schema amongst two microservices would be an even worse idea because it would effectively create a monolith masquerading as two microservices. You'd inherit all of the bad things that come from monoliths with none of the benefits of microservices. Data would be badly encapsulated, upgrades would be difficult, and failure would spread to all microservices. I would suggest refactoring the design such that this kind of sharing is not necessary.
What is microservices in business?
Microservices is about having independent services that are autonomous but can work together. The sharing of databases compromise that goal. Let's examine both.
Why is sharing a database important?
The motivations for sharing a database are obvious. Less infrastructure, cost savings and simplicity. It becomes much easier to join data from different services.
What should be the table namespace for microservices?
At a minimum, the tables that are specific to the microservices should be in specific schemas/”databases”/table namespaces. Among other things, if your services get too heavy to share instances and you need to split things up, the split operation will be much easier to do if you can just dump one db out and migrate it to a new instance versus having to execute the migration table-by-table.
What happens when Service B directly references tables that Service A owns?
If Service B directly references tables that Service A owns then modifying these tables requires far more planning and collaboration between Teams A and B, which slows the process down until both teams can make changes and coordinate deployment of those changes.
Should I split a database?
I’ve tried both approaches, and I would definitely recommend splitting up to a database per service unless there are very strong reasons not to. If you do share a database, at least be very conscious about it to avoid the microservice boundaries becoming blurred.
Do microservices interfere with each other?
Sure. I do it all of the time. Each (micro)service gets its own unique connection to the database so the different services don’t interfere with each other.
Why do we separate access to data?
The reason why we separate access to data is old good encapsulation. We decrease risk of unexpected modification of data by some strange service. That’s why we make class variables private in OOP and use containers to run our services. The problem is that data doesn’t belong to our microservice. It belongs to the database, which is completely different service. Encapsulating DB data with Users microservice we make it basically as proxy for the database. Of course, there can be cases, where a service applies sufficient transformation to the data, but it that case it’s new data already and it belongs to that microservice. Such data definitely can be requested via service API.
Can an order service modify a table in a database?
So it’s a pure matter of discipline. Of course more your services teams separated, then you probably should move more to the direction of API. Yes, by default our Orders service could modify all the tables in the DB. But you can leverage DB ACL for that, if your database allows you to do it.
Do orders have to be aware of schema?
Yes, Orders must be aware of all the tables basically and DB schema in general. But in case of information hiding design, the service instead must be aware of API methods, which is still the same kind of extra knowledge. Changing a schema is a real problem.
Can you build micro services but not monolith?
In reality if you want to build exactlty micro services but not just monolith with couple of side services, you’ll have to think about splitting your business domain. And here you unlikely find any good advices. First of all, in many cases it’s just not completely solvable, second, after a meeting with the project manager your business domain will change, breaking all the existing architecture. And you probably know managers attitude to refactoring.
Can you change a schema in a service API?
Changing a schema is a real problem. But basically there is not many differences between changing DB schema and service API. In both cases you can make it backward compatible and in both cases you can break everything. So it’s a pure matter of discipline. Of course more your services teams separated, then you probably should move more to the direction of API.
Can you restrict access to a shared database?
So when you do, it’s much easier to stay with shared database, just create separated users per microservice to restrict data access.
Is synchronous API direct dependency?
That’s the problem of synchronous API, it’s a direct dependency.
