I have A requirement where the current schema to be used is stored in db table;(schema_a or schema_b).
The application is loaded with default schema
spring.jpa.properties.hibernate.default_schema=schema_a
Now when the data in table is updated to B I want to consider all jpa query to use schema_b without any down time at server.
Your question is not clear enough to provide some code to your question, but you can catch inspiration from the following articles:
https://spring.io/blog/2007/01/23/dynamic-datasource-routing/
Spring Boot - Change connection dynamically
Related
I created user in oracle database and I am trying to create session but I find many ways in spring boot so what is the easy way if I want to create classe connections using the Username and Password ?
You can jdbc template, spring data JDBC or spring data JPA, well depending on your use case.
If your data model is quite complex, you should avoid using the JDBC template as you will need to write prepared statements which can be cumbersome. JPA will allow you to use object-oriented programming principles and also will help you map the entities to your database columns.
For example, if you are going to use spring data JPA, you need to set the application properties as follows:
spring.datasource.type=oracle.oracleucp.jdbc.UCPDataSource
spring.datasource.oracleucp.connection-factory-class-name=oracle.jdbc.pool.OracleDataSource
spring.datasource.oracleucp.sql-for-validate-connection=select * from dual
spring.datasource.oracleucp.connection-pool-name=UcpPoolBooks
spring.datasource.oracleucp.initial-pool-size=5
spring.datasource.oracleucp.min-pool-size=5
spring.datasource.oracleucp.max-pool-size=10
This would behind the scene create an Oracle Datasource. In this example, we are using Oracle Universal Connection Pooling. You can also use HikariCP which is quite popular.
check this out
If you want to use UCP with above properties then you must have SpringBoot version higher than 2.4.0.
Check out the Spring Boot code sample on GitHub.
I created a spring boot project and I link it with my DB under PgAdmin.
I've modified the application.properties correctly and created a class named "user" and its repository "userRepository" but I don't know if this will automaticly create the user table in the DB (I used annotations) or I have to create it in PgAdmin ?
Do I need to specify any controller or webController if I want to have Crud operations ? And where does the CrudRepository exists do I need to generate it and how ?
Excuse me this my first experience with spring, I will really appreciate if you guys can help me.
Thanks in advance.
For your first question:
I don't know if this will automaticly create the user table in the DB
You have several ways how to create your tables, for example with property in application.properties file
spring.jpa.hibernate.ddl-auto = [none|validate|update|create-drop]
where none means this configuration not affect existing database
update means updating changes in database
create-drop means creating all tables from scratch according your project entities classes.
You can check this documentations for additional information
https://docs.spring.io/spring-boot/docs/1.1.0.M1/reference/html/howto-database-initialization.html
59.2 Initialize a database using Hibernate
also you can check how to initialize database with existing sql scripts files in documentation above
59.3 Initialize a database using Spring JDBC
For question: Do I need to specify any controller or webController if I want to have Crud operations ? And where does the CrudRepository exists do I need to generate it and how ?
Yes you should create controllers to handle requests and repositories to work with JPA.I also suggest check tutorial first, for example this one (first in google)
https://bezkoder.com/spring-boot-jpa-crud-rest-api/
I have created two spring boot microservices for experimenting purposes, both use hsqldb. Is there a way to see the hsqldb details like what is the name of the db that spring boot created, username, password, what tables are there in each one and to query those tables.
You can use the built-in SQL functions and INFORMATION_SCHEMA views in HSQLDB to check these properties. See the Guide http://hsqldb.org/doc/2.0/guide/
But the quick and easy way is to use a file: database connection and check the *.script file of the database, which contains SQL statements that set the properties and create the tables.
I working on a project which uses Spring boot , Spring Data JPA and postgres .There is a problem that can't solve .
When my application start up ,The database not ready yet . It need to add to application at runtime . But I also want to initialize a database using JPA.
just like spring.jpa.hibernate.ddl-auto：create-drop，Unfortunately Initialize a database using JPA will happen at application startup.
My question is that how to delay spring data jpa DDL generation. now we can't add a datasource at application runtime.
I am searching for a long time on net. But no use. The AbstractRoutingDataSource may be not suit for us, because we don't have a datasource at begin .
Please help or try to give some ideas how to achieve this
Thanks in advance
AbstractRoutingDataSource is not useful as it requires pre-configured datasources.
just check this stackoverflow question, it shows how you can add/remove datasources at runtime. While it doesn't support hibernate's delayed ddl creation but you can create database tables in runtime datasources using schema.sql and inserts some constants using data.sql.
I am working on spring batchupdate ,I search on google I didn't find any solution for my problem.
I have two databases(MySQL,ORALCE) I want to read data from mysql and write into oracle by using batch update .
Your problem is unclear.
You can first read the data from MySQL with one Spring JdbcTemplate object initialized with MySql data source, and then use another JdbcTemplate object, initialized with Oracle data source, to write the data.
If you want to do it in one transaction, you will have to use distributed transactions/XA libraries, such as Atomicos, and Spring distributed transaction manager. See here https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-jta.html for details on Spring integration with distributed transactions libraries.