The requirement is - In my application, having more than 5 databases, those are source and target databases. through UI page, User have to choose source database and target database and based on this data we have to fetch records from one database and store to target database (both having same tables)..
In spring boot, is it possible to switch databases? if not then should i go with JDBC Programing?
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i am working on a spring boot project I am using multiple databases and all databases have same table I need to pass a number in the request based on the number I need to select one database from all databases and run the query any suggestion how to do it
I have a SpringBoot application with in memory H2 database and Spring Data JPA.
I need to configure a #Scheduled job that drops and recreates the schema and loads it with fresh data from a file.
How can I programmatically recreate the schema in my application?
You can use database version control tool like eg Liquibase to create and maintain database schema definition as well as initial data. Than, you will be able to easily invoke database migration including drop of whole schema during applicaiton runtime. IT has some integration with Spring Boot already.
Keep in mind, that you will have to lock database access in order to execute migration - DDL is not transactional, so database will be of no use anyway during the migration process and you app can yeld many errors during that time.
If locking is not an option - you should be able to create another instance or at least separate schema in running instance, run migration against it and if everything is done, "switch" peristence context to use brand new schema (and probably remove the old one)
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 am using spring + hibernate transaction manager in the my project. Initially I am connecting to main database and retrieving several projects in a company, say if there are 200 projects each project will have database associated with it, I want to connect to database associated with the project that is selected by user at run time.
Is there any ideal way to connect to database at run time?
There's a Spring abstraction AbstractRoutingDataSource that has been around for a long time, and that fits your bill
The general idea is that a routing DataSource acts as an intermediary
- while the ‘real’ DataSource can be determined dynamically at runtime based upon a lookup key.
There is a good post and a newer tutorial, where you can learn more details.
I would like to use hsql within my DAO unit tests for a web application. The web app is written against mysql and uses three different schemas within the same mysql database. Some schemas has FK relationships with data in the other schemas. If I'm to unit test, I must be able to execute against a database that can hold multiple schemas.
I know that HSQL supports multiple schemas, but I don't know how to configure hsql to have multiple schemas set up for an in-memory database. I read that I can define multiple schemas in the server.properties file, but the file needs to be in the location of where the java class was called -- the junit.jar location? If so, that would be hard to support in my Java Maven application. How can I:
Run an in-memory hsql database to start up with three databases?
Where would I place the server.properties file in my Maven app?
Could I point hsql to use a server.properties file in a location other than where the junit jar is (that's a showstopper for me)?
Is it possible to configure multiple schemas for an in-memory database just via a tricked out jdbc url?
I wish I could untangle the schemas from each other, but that's not possible at this time.
Thanks for your help!
HSQLDB supports multiple schemas in the same database. Foreign keys can reference tables from different schemas. The following apply to the very latest HSQLDB 2.2.6 snapshot available from http://hsqldb.org
Before running your tests, execute CREATE SCHEMA schemaname for each schema.
Doesn't matter where, you can specify the absolute path on the command line arguments when running. See the HSQLD Guide and JavaDoc on server.
Yes.
No. You use the SQL statement to create the schemas.
Note you have two options for running HSQLDB, one is as a server, the other is as an embedded database. In the case of server, it must be started before the test run. In both cases, you need to connect to the database and create the schemas before your tests.
It is possible to create different db by setting db name. By default, it creates the db name as testdb, but in case we want to create multiple db, then set the name explicitly.
new EmbeddedDatabaseBuilder()
.setType(EmbeddedDatabaseType.HSQL).setName("DB_NAME")
.addScript("DDL.SQL")
.addScript("DML.SQL")
.build();
If you run the below line mutiple time, you can see the databases:
DatabaseManagerSwing.main(new String[] { "--url", "jdbc:hsqldb:mem:" + dbnaes, "--user", "sa", "--password", "" });