I am new to Springboot and trying to build a small rest-service. We have a DB deployed on different environments (e.g. DEV, TEST). The rest-service will make a call to the appropriate database based on the received query param (e.g. ?env=TEST). The schemas of the deployed database are the same, the difference is only in connection string. I have some questions related to this task.
I read a few articles how to work with multiple databases using Spring JPA (for example this one: https://www.baeldung.com/spring-data-jpa-multiple-databases). It did work, but in the given example they get different entites from different databases using different queries, in my case the entity and the query is the same, but I still have to duplicate repositories, transactionManagers, entityManagers etc because of different datasources. And this is just two environments and I have more of them.
I have another thought that I might need to recreate the repository each time I process a request (to make the repository non-singleton). I am not sure if it is a good practice.
Maybe it worth to use JDBCTemplate instead of Spring JPA in this case?
Could you please suggest something how to approach such a task?
Related
I have two databases with only two deficiencies: URL and data, the tables are the same, even some tables's contents are the same.
I have managed two have each one as a separate datasource following this tutorial : https://www.baeldung.com/spring-data-jpa-multiple-databases .
However, code maintainability is hard, all made modifications on an entity, repository or even entity id class in one datasource have to be duplicated to the other one each time.
I am looking for configurations or practices or even ideas to make the code maintainability easier.
using spring 2.7.4
I have a use case where I need to create exact same postgresql database in two different regions. Everything is same in these two databases i.e same schema and same tables and same data.
I have a use to achieve distributed transaction. So if a request land in region-a and write to region-a database to let's say Person table, then exact same record must be either written in Person table in both these database or if there is any error, write attempt should be rolled back.
I am trying to figure out if I can attach two different datasources with same Person Entity and CRUD repository in spring so the respoistory.save() method can write to Person table in both the databases.
So far, I have come across AbstractRoutingDataSource but that is for achieving multi tenancy in the databases. Other solutions are found are slightly different where use case is to write different records in different database (mostly sharding based on various data points).
Does spring provide any out of the box solution so I can achieve transactional write to same table in two different databases.
Does spring provide any out of the box solution so I can achieve transactional write to same table in two different databases.
Depends on your definition of "out of the box" - it doesn't itself implement distributed transactions, but does have support for using libraries that do. It is however relatively complicated to get everything working correctly, and requires additional components to be carefully configured in your runtime environment.
Spring Boot 2.x documentation on distributed transactions is here: https://docs.spring.io/spring-boot/docs/2.7.x/reference/htmlsingle/#io.jta
The Spring Boot 3.x documentation is here: https://docs.spring.io/spring-boot/docs/current/reference/html/io.html#io.jta but it's also worth noting that for 3.x, the Spring Boot team have changed direction and decided that integrated support should be provided by the relevant JTA provider (cf. https://github.com/spring-projects/spring-boot/issues/28589 ), and so there's projects like https://github.com/snowdrop/narayana-spring-boot
In My Application, Using the below technologies
Spring boot 2.7.x
Cassandra
spring batch 5. x
java 11
As part of this, I need to extract data from the Cassandra database and need to write out the file
so here I need to use queries to fetch data so
just want to know what is the best way to maintain all queries at one place so any query changes come in the future, I shouldn't build the app rather just need to modify the query.
Using a repository class is necessary. If you are using JPA i recommend using a repository for each Entity class. With JDBC it is possible to create a single repository which contains all the queries. To access the query methodes i would use a service class. In this way your code is structured well and maintainable for future changes.
I'm playing around with Atomikos. Using this as a starting point: https://www.fabiomaffioletti.me/blog/2014/04/15/distributed-transactions-multiple-databases-spring-boot-spring-data-jpa-atomikos/
In my use case, I'm going to have essentially two physically separated databases that are going to be identical.
This requirement is based on GDPR and basically, we will have databases in different regions.
Some of the tables need to be in sync and one of the ideas is to use Atomikos (2-phase commit ) to implement distributed transactions.
What I'm trying to implement is to use one single spring repository that is going to persist data into two physically divided databases.
All examples provided by atomikos are dealing with two databases but with different tables using different repositories.
Is it possible to configure atomikos on the way that I'm using a single repository that is going to persist data in both data sources?
In the ideal case, I'm looking for the possibility to mark service method with a specific annotation and specific transaction manager and only in that case to force that specific method or better to say invoked repository methods in that service methods ( save, saveAll methods and so on ) to persist data in both databases. When there is no specific annotation on a service method to persist only in a single database to not perform distributed transaction.
I have a situation where I have two SpringBoot microservices which share the same database schema. The schema is maintained by a liquibase changelog file. One service reads from the database, and the other service is responsible for writing to the database.
Right the Writing Service owns the liquibase changelog file, which means the Writing service owns the schema. And the way I validate the Reading Service is to deploy the Writing service first into a test environment followed by the Reading Service, and then execute end-to-end tests against the Reading Service.
Is there a way for both services (two separate apps, two separate repos) to share the liquibase changelog file? I feel this is similar to a contract test as the changelog file will be the contract for both services, but wasn't sure if there was something provided by Liquibase, Spring, Pact, etc that supported this idea.
Thanks for your time!
I think it won't count as a legit answer, but two solutions come to mind:
since your second service reads from the database, I suppose you have a full set of entities there, and entities are supposed to match your database schema. And since you're using Spring, I suppose you can add spring.jpa.hibernate.ddl-auto=validate to the application.properties file. This will validate your database schema against the entities.
You can create a separate library which will contain all the changeLogs. After that you can include this library to both services, so liquibase will validate that all changeSets are executed during application's deployment. But you should make sure that all your changeSets have preConditions, so your deployment won't fail and there won't be any duplicates in the DB schema.