I use Hibernate-Spring and I am trying to access a specific schema in a db but don't know how. The name of the table is not doing the trick. I was hoping that annotation would help be but it hasn't so far. Note: I am not trying to create a schema, I just want to access it. I use Spring 2.5.
Set schema in your mappings:
#Table(name="myentity", schema="some")
<class name="MyEntity" table="myentity" schema="some">
or use default:
hibernate.default_schema="some"
Related
I got to know Java spring JPA a couple days ago and there is one question which really makes me confused.
As I create a repository and use 'save()' method to save some objects into it. How does it know what type of database I am using and which local location to save.
I know I can config database (h2) like:
spring.datasource.url=jdbc:h2:mem/mydb
Then JPA will know: ok you are using h2 database and url is "jdbc:h2:mem/mydb"
However, some people said this config is not mandatory. If without this config, how does JPA knows which database I gonna use?
From the spring-boot documentation:
You should at least specify the URL by setting the spring.datasource.url property. Otherwise, Spring Boot tries to auto-configure an embedded database.
The following class is responsible for providing default settings for embedded DB: org.springframework.boot.autoconfigure.jdbc.DataSourceProperties
public String determineDatabaseName() {
...
if (this.embeddedDatabaseConnection != EmbeddedDatabaseConnection.NONE) {
return "testdb";
}
...
}
This answer can also be helpful: Where does the default datasource url for h2 come from on Spring Boot?
I am working now with oracle and spring jdbc but I don't want to use the schema in my sql statements:
Example: Select * from SCHEMA.table
Is there any way to set default schema in application.properties or application.yml?
Assuming you define your database connections using spring datasources, you can set the default schema when defining the datasource configuration:
spring.datasource.schema = #value for your default schema to use in database
You can find more info here: Spring Boot Reference Guide. Appendix A. Common application properties
After doing some research, looks like Oracle driver doesn't let you set a default schema to work with, as noted here:
Default Schema in Oracle Connection URL
From that post, you have two options:
Execute this statement before executing your statements:
ALTER SESSION SET CURRENT_SCHEMA=yourSchema
Create synonyms for your tables/views/etc (which I find really cumbersome if we're talking about lots of elements in your database).
I would advice using the first option. From what I see, Spring boot doesn't offer a simple way to execute a statement when retrieving the connection, so the best bet will be to use an aspect around the getConnection method (or the method that retrieves the connection from the data source) and execute the statement there.
From your comment, an easier way to solve it is by using a script in spring.datasource.schema:
spring.datasource.schema = schema.sql
And then a file squema.sql with the following:
ALTER SESSION SET CURRENT_SCHEMA=mySchema
In spring boot, I've found another way of doing it,
#Bean
#ConfigurationProperties(prefix="spring.datasource")
public DataSource dataSource(#Value("${spring.datasource.schema}") String schema) {
DataSource datasource = DataSourceBuilder.create().build();
if(!schema.isEmpty() && datasource instanceof org.apache.tomcat.jdbc.pool.DataSource){
((org.apache.tomcat.jdbc.pool.DataSource) datasource).setInitSQL("ALTER SESSION SET CURRENT_SCHEMA=" + schema);
}
return datasource;
}
I found another way to get around this by updating entity class with
#Table(schema = "SCHEMA_NAME" ,name = "TABLE_NAME")
If you are using hikari, use spring.datasource.hikari.schema=YOUR_SCHEMA.
Works for me with SpringBoot + tomcat using Oracle.
I was having issues with the currently accepted answer; specifically, the schema would only be changed from the initial connection. If your app uses a connection pool, you need to configure the pool to apply SQL for each connection.
For instance, using the default jdbc pool in Spring Boot 1.5.x (Tomcat):
spring.datasource.tomcat.init-s-q-l = ALTER SESSION SET CURRENT_SCHEMA=mySchema
Connecting to the database as your user, you can create a trigger that will change the schema each time you login:
CREATE OR REPLACE TRIGGER LOGON_TRG
AFTER LOGON ON SCHEMA
BEGIN
EXECUTE IMMEDIATE 'ALTER SESSION SET CURRENT_SCHEMA = foo';
EXCEPTION
when others
then null;
END;
/
Another option is to create a datasource wrapper. Create the datasource as normal and then create the wrapper that forwards all methods except for the getConnection methods. For those I just added SQL to set the schema. We have multiple datasources and this allowed us to specify a different schema for each datasource. If anyone knows if there's an issue with this I'd love comments. Or if there's an alternative that uses the properties.
I am working on a program which uses memory DB(in my case, it is apache derby, is included in jdk 1.6 and further).
I can set resources like dataSource and sqlSession bean to 'root-context.xml', but do not know how to create DB and table.
If table and DB are already exist, I can do CRUD via usual way. However, this time I should make a DB and new Table on first time. I already tried Maker Class and put 'init-method' to create DB and table before was is uploaded, but it does not work.
How can I make a Spring was program which makes Memory DB and Table before running?
P.S.
I really like to use CRUD in Spring way like SqlSessionTemplate or annotation. But almost of derby sample uses PreparedStatement or Statement. If you have any good sample links what I am looking for, share please. Thanks :D
You need to use the jdbc namespace which includes an embedded-database tag with support for Derby out of the box. The tag takes nested script tags to define scripts to run (they are run in the order declared).
<jdbc:embedded-database id="myDB" type="DERBY" >
<jdbc:script location="classpath:sql/schema.sql"/>
<jdbc:script location="classpath:sql/data.sql"/>
</jdbc:embedded-database>
In my application, when user logs in to the system the system reads some setting from DB and stores them on user's session. The system is performing this action by a JPA query using EclipseLink (JPA 2.0).
When I change some settings in DB, and sign in again, the query returns the previous results. It seems that EclipseLink is caching the results.
I have used this to correct this behavior but it does not work:
query.setHint(QueryHints.cache_usage,cacheUsage.no_cache);
If you want to set query hints, the docs recommend doing:
query.setHint("javax.persistence.cache.storeMode", "REFRESH");
You can alternately set the affected entity's #Cacheable annotation
#Cacheable(false)
public class EntityThatMustNotBeCached {
...
}
If you're returning a some kind of configuration entity and want to be sure that data is not stale, you can invoke em.refresh(yourEntity) after returning the entity from query. This will force the JPA provider to get fresh data from the database despite the cached one.
If you want to disable the L2 cache you can use <shared-cache-mode>NONE</shared-cache-mode> within <persistence-unit> in persistence.xml or use Cacheable(false) directly on your configuration entity.
If you're returning plain fields instead of entities and still getting stale data you may try clearing the PersistenceContext by invoking em.clear().
I am working on an engine that is doing the following:
gets data provider info from DB (that tells me to what database & schema details to connect to get my data)
use that info to connect to the database and get my data, that later I use to build some XML content.
The standard setup to handle and isolate database connection management would be to create a DataSource bean (I'm using Spring to wire my components) and inject that in my ProviderConfigDao (loads connection config) and ContentDao (loads data using connection details loaded previously). This would nicely isolate the handling of the connections from the actual code, thus the DAO classes not needing to know how and when a connection is created/opened/closed etc.
This setup doesn't work unfortunately, as when I create my connection, I need to be able to specify the database schema. I don't know all the different schemas from the beginning, so I can't create a set of DataSource objects to cover all of them, thus the DataSource object must be created at runtime and it's creation hidden from the users.
The only solution I can think of is:
Have another class/interface (DataSourceProvider) having one method:
//Gets the connection URL as parameter (which includes the schema name).
DataSource getDataSource(String url);
Add a bean in Spring config to provide a custom implementation for it that manages creation of DataSource objects for each schema.
Inject that object to my DAO classes instead of the DataSource object.
It's not a bad solution, but I was wondering if there is maybe support for something like this already in some open source package ... I'd rather use something already done and tested then reinvent the wheel.
Cheers,
Stef.
there's a JDBC Utils to get all the metada from a database org.springframework.jdbc.support.JdbcUtils
parameters:
DataSource
Implementation of org.springframework.jdbc.support.DatabaseMetaDataCallback