Develop Reference

PostgreSQL - User lacks priviledge or object not found

I have an application that is using Hibernate and PostgreSQL, I compile it with Maven to a WAR and deploy it to a Tomcat 8.0, and sometimes I have the problem of
this error :
"User lacks priviledge or object not found: TABLE_NAME".
Well obviously the answers found to this problem are always "Check the priviledges to that user, and check if the table/database exists".
This absolutely is not the problem because this happens sporadically, i.e. My application is working fine, and when I deploy a new version of it, sometimes after the deploy it throws out this error.
I always deploy my application with Jenkins, and the deploys to Tomcat are successful, the application is working, but if I invoke an action that consumes a database service, it goes haywire with this error. This clears up after 2 to 3 clean deploys on it (i.e. I stop Tomcat, clean the directory, start it and run deploy with Jenkins again with the same version of code).
Still it is very odd that after a clean deploy it does not solve the problem. Even after restarting the whole server (not Tomcat, the Windows Server), it still happens.
The closest explanation I read about possible causes to this, is that sometimes it can create a ghost connection to the database and when it tries to query something it can't because it is not really connected.
The database is on the same server as the Tomcat, so the application points to localhost to connect to the database. I don't think this is related because it also happens in a Quality Rnvironment where the database is in a different server.
My configuration file regarding database is this:
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
<alias name="appDataSource" alias="jpaDataSource" />
<alias name="jpaTransactionManager" alias="appTransactionManager" />
<bean id="appDataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="org.postgresql.Driver" />
<property name="url" value="${postgre.url}" />
<!-- jdbc:postgresql://127.0.0.1:5432/DEV_DATABASE -->
<property name="username" value="${postgre.username}" />
<property name="password" value="${postgre.password}" />
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="jpaDataSource" />
<property name="jpaVendorAdapter" ref="jpaVendorAdapter" />
<property name="packagesToScan" value="${persistence.jpa.packagesToScan}" />
<property name="jpaProperties">
<props>
<prop key="hibernate.temp.use_jdbc_metadata_defaults">false</prop>
<prop key="hibernate.jdbc.use_get_generated_keys">true</prop>
</props>
</property>
<property name="sharedCacheMode" value="ENABLE_SELECTIVE" />
<property name="validationMode" value="NONE" />
</bean>
</beans>
Anyone got ideias of what this could be?

It's been a few months and I've been able to find out what was happening.
Apparently I had a configuration of an embedded-database and sometimes (though rarely) the application would connect to this embedded-database and not the one that I had configured to connect to Postgres Database.
The tag was:
<jdbc:embedded-database id="appDataSource" />
Because this was an empty mockup database, it would fire up the error of "User lacks priviledge or object not found" because the table did not exist in this empty database.
After removing this, the problem was solved, it now always connects to the correct database.

Second level caching in hibernate while migrating from JBoss to TomEE

I need to migrate my application built in GWT from Jboss to tomEE. The application has second level caching enabled in hibernate using Jboss cache. Is it possible to use Jboss cache in tomEE or do I have to find an alternative? If possible, can anyone please help me with the configuration of hibernate.cfg.xml? Below is the configuration
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">com.sybase.jdbc3.jdc.Sybdriver</property>
<property name="hibernate.connection.url">xyz...</property>
<property name="hibernate.connection.username">xyz..</property>
<property name="hibernate.connection.password">xyz..</property>
<property name="transaction.factory_class">org.hibernate.transaction.JTATransactionFactory</property>
<property name="transaction.manager_lookup_class">org.hibernate.transaction.JBossTransactionManagerLookup</property>
<property name="dialect">org.hibernate.dialect.SybaseASE15Dialect</property>
<property name="generate_statistics">false</property>
<property name="jdbc.use_scrollable_resultset">false</property>
<property name="cache.provider_class">org.hibernate.cache.jbc.JBossCacheRegionFactory</property>
<property name="cache.use_second_level_cache">true</property>
<property name="cache.use_minimal_puts">true</property>
<property name="cache.use_structured_entries">true</property>
<property name="cache.use_query_cache">true</property>
<property name="cache.region.factory_class">org.hibernate.cache.jbc2.JndiMultiplexedJBossCacheRegionFactory</property>
<property name="cache.region.jbc2.cachefactory">java:CacheManager</property>
<property name="cache.region.jbc2.cfg.entity">mvcc-entity</property>
<property name="cache.region.jbc2.cfg.collection">mvcc-entity</property>
<property name="cache.region.jbc2.cfg.query">local-query</property>
<mapping resource="book.hbm.xml" />
</session-factory>
</hibernate-configuration>

We cannot achieve the second level caching using JBoss cache in TomEE. We have implemented a similar caching mechanism using Ehcache which is a little slow but works fine.

<property name="cache.region.jbc2.cfg.entity">mvcc-entity</property>
<property name="cache.region.jbc2.cfg.collection">mvcc-entity</property>
<property name="cache.region.jbc2.cfg.query">local-query</property>
We see that entity, collection, and query caching are enabled by using JBoss cache implementation specific to JBoss server. In the case of TomEE, we cannot have the same configuration. You would have to implement a different caching technique using different caching technologies available and match it with the usage of second-level cache(like say read-only, read-write, transactional etc.). In a similar setup, I had used "Ehcache" and that had solved the problem.

What is the proper way to create a datasource in a spring web application?

I have two ways to create datasource:
Inside spring context
<bean id="dataSource"
class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost:3306/mkyongjava" />
<property name="username" value="root" />
<property name="password" value="password" />
Tomcat JNDI
<bean id="dataSource" class="org.springframework.jndi.JndiObjectFactoryBean">
<property name="jndiName" value="java:comp/env/jdbc/UsersDB"/>
What are the benefits and problems of creating the datasource using spring or using tomcat jndi ?

There is nothing like good practice among this. The good one is the one which is good for use case. They both have pros and cons.
When u have use cases where u are trying to deploy the apps on a server environment where multiple apps share a common datasource or datasource components are managed by the Server administration then probably the best way to use is through a JNDI context. The server has the DataSource kept ready so that the application can directly get that object, bind to itself and use the datasource.
When u have use case where application runs inside a embedded server container or cloud containers where the server also is embedded along the build packs creating datasource with in the application and using them would be a good solution. Also in non web application environments creating datasource would be good.
To summarize, use cases where datasource is non managed by the application better to go for a JNDI context.
Try to figure out what is the deployment model of your application and figure out what is good for u. Also try to use a datasourcepool implementations to improve performance like DBCP, C3P0 or Hikarcp.

The first approach, using the class DriverManagerDataSource, is useful for test or standalone environments outside of j2ee container.
The second approach, using the jndi data soure, is recommended to be used in the j2ee container.
The below reference clearly states these approaches.
http://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/jdbc/datasource/DriverManagerDataSource.html

I am using it as below. Works for me since project is configured at the time of architecture design. And its live in production.
<!-- Local Apache Commons DBCP DataSource that refers to a combined database -->
<!-- (see dataAccessContext-jta.xml for an alternative) -->
<!-- The placeholders are resolved from jdbc.properties through -->
<!-- the PropertyPlaceholderConfigurer in applicationContext.xml -->
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="validationQuery" value="${jdbc.validationquery}"/>
<property name="testOnBorrow" value="${jdbc.testonborrow}"/>
<property name="driverClassName" value="${jdbc.driverClassName}"/>
<property name="url" value="${jdbc.url}"/>
<property name="username" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>
</bean>
<!-- Transaction manager for a single JDBC DataSource -->
<!-- (see dataAccessContext-jta.xml for an alternative) -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
you can also refer to this. Best contribution of Genious to java developers.
https://www.mkyong.com/spring-boot/spring-boot-jdbc-oracle-database-commons-dbcp2-example/

The best practice is to not to expose the database configuration in any of the code that you have written. It is always best to configure inside the server console and expose it as a jndi. Inside spring configuration file, get the database instance as:
<jee:jndi-lookup id="dataSource" jndi-name="jdbc"/>
and configure the database transaction manager as:
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource"/>
</bean>
The key note here is do not expose the database configuration.

Using Ignite for Hibernate 2nd level cache with S3 discovery, changes are not progagated

We have deployed a cluster to AWS configured to use Ignite as a hibernate 2nd level cache, and we're using S3 discovery. On startup we can see the nodes do connect to each other correctly.
However, when a hibernate entity is updated on one server, the change is not propagated through the cluster so other servers continue to have the old value.
Here is a snippet of our ignite config..
```
<!-- Basic configuration for transactional cache. -->
<bean id="transactional-cache" class="org.apache.ignite.configuration.CacheConfiguration" abstract="true">
<property name="cacheMode" value="REPLICATED"/>
<property name="atomicityMode" value="TRANSACTIONAL"/>
<property name="writeSynchronizationMode" value="FULL_ASYNC"/>
<property name="backups" value="0"/>
</bean>
<bean id="ignite.cfg" class="org.apache.ignite.configuration.IgniteConfiguration" >
<property name="discoverySpi" ref="discoverySpi"/>
<property name="gridName" value="hibernate-grid"/>
<property name="cacheConfiguration">
<list>
<bean parent="transactional-cache">
<property name="name" value="hibernate.io.milton.vfs.db.Auditable"/>
</bean>
```
The exact same application code, when configured with hazelcast 2nd level cache, does work.
I'm sure there's just something wrong with our config. Can anyone suggest a pointer?

Most likely you hit a known issue with binary format which is used as the default one in Ignite. See the warning callout here for details: https://apacheignite-mix.readme.io/docs/hibernate-l2-cache#l2-cache-configuration
Switching to OptimizedMarshaller should fix the issue.

Using JNDI for for my datasource and location of properties files

I want to use jndi in my spring mvc application for 2 things:
datasource settings
store the location of my properties file so I can do a lookup in my code
I actually have 2 applications, 1 is a spring mvc and the other is a spring so I'm planning on using the same jndi settings for both.
Also, the 2 applications run on different contains (tomcat and jetty), I've never used jndi before so I hope I can define this in a single location and have both applications point to the same jndi file (assuming its a file).
So as for #1, my datasource settings in my spring context file are currently:
<bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource" destroy-method="close">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost/mydb_development"/>
<property name="username" value="devuser1"/>
<property name="password" value="123"/>
<property name="maxActive" value="100"/>
<property name="maxIdle" value="30"/>
<property name="maxWait" value="1000"/>
<property name="defaultAutoCommit" value="true"/>
<property name="removeAbandoned" value="true"/>
<property name="removeAbandonedTimeout" value="60"/>
<property name="testOnBorrow" value="true"/>
<property name="validationQuery" value="SELECT 1"/>
</bean>
Can someone tell me how I can extract this out to use JNDI, confused, is it a separate file that has to be in my class loader, or do I hard code the path in my spring context file?
And as for #2, in my code I am currently loading a properties file that is in my class path like:
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
InputStream is = classLoader.getResourceAsStream("test.properties");
Now the test.properties file is in my classpath so it works out of the box, but what I want to know/understand is if I could somehow use jndi to lookup the location of the properties file (if that makes sense?) and not have this file in my classpath potentially.
I did google around and I know in spring I can pull in jndi using:
<jee:jndi-lookup id="dataSource" jndi-name="jdbc/mysqlDataSource" />
But what I don't understand is, where is the actual file that has the settings? Can it be in a location other than my web.xml file? (my other application again is using spring, but it is a daemon so it doesn't have a web.xml file).
The goal for me is to be able to change the values of the jndi file (like username, passwords, file paths) and NOT have these embedded into a jar. I want to be able to manually edit these files on the production server or dev servers and just restart the container.

I'm kinda rusty with spring but I remember using a PropertyPlaceHolderConfigurer, something like:
<bean id="propertyPlaceholderConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreResourceNotFound">
<value>true</value>
</property>
<property name="ignoreUnresolvablePlaceholders">
<value>true</value>
</property>
<property name="locations">
<list>
<value>file:path to your file
</value>
<value>file:path to another file if needed
</value>
</list>
</property>
</bean>
Then you can use the values on the .properties defined on the list directly. i.e. if you have a property like
db.driver=com.mysql.jdbc.Driver
you can use it like
bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource" destroy-method="close">
<property name="driverClassName" value="${db.driver}"/>
when you want to define a value.
If you want further control over the file, the path to the file itself can be registered on your server and you can look it up through JNDI, changing
file:path to your file
into
file:${propertiesFilePath}
I'm pretty sure you can look up those configuration properties by code too by a normal JNDI lookup.