how can I make hibernate to create tables only if they didn't exists?

Question

how can I make hibernate to create tables only if they didn't exists? I just set "hibernate.hbm2ddl.auto" to "update" but it is giving error while restarting the server ie- error is like "relation already exists"

My persistence.xml :-

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
         version="2.0">
<persistence-unit name="com.adwork">
    <description>Adwork</description>
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <!-- <class>com.mkyong.bean.User</class>  -->
    <properties>
        <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/>
        <property name="hibernate.hbm2ddl.auto" value="update"/>
        <property name="show_sql" value="true"/>
        <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>

        <property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver"/>
        <property name="javax.persistence.jdbc.url" value="jdbc:postgresql://localhost:5432/adwork"/>
        <property name="javax.persistence.jdbc.user" value="root"/>
        <property name="javax.persistence.jdbc.password" value="root"/>
    </properties>
</persistence-unit>

please help. thanks

Here is the error :-

ERROR: org.springframework.web.context.ContextLoader - Context initialization failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'applicationStartUp' defined in ServletContext resource [/WEB-INF/spring/root-context.xml]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: com.adwork] Unable to build Hibernate SessionFactory
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:775)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:861)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4727)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5189)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:724)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:700)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:734)
at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:596)
at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1805)
at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: com.adwork] Unable to build Hibernate SessionFactory
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:877)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:805)
at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:58)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:55)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:39)
at com.adwork.survey.config.ApplicationStartUp.initIt(ApplicationStartUp.java:27)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeCustomInitMethod(AbstractAutowireCapableBeanFactory.java:1706)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1645)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
... 25 more
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [alter table person add column createdDate timestamp not null]
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:420)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:438)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.migrateTable(SchemaMigratorImpl.java:247)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:170)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:60)
at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:129)
at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:97)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:481)
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:802)
... 36 more
Caused by: org.postgresql.util.PSQLException: ERROR: column "createddate" of relation "person" already exists
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2270)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1998)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:570)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:406)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:334)
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56)
... 46 more

My domain class :-

@Entity
@Table(name = "person")
public class Person implements Serializable
{
/**
 * 
 */
private static final long serialVersionUID = 5129388836708407722L;

@Id
private Long id;

@OneToOne
@JoinColumn(name = "userId")
private Users user;

@Column(name = "firstName",nullable = false)
private String firstName;

@Column(name = "middleName",nullable = false)
private String middleName;

@Column(name = "lastName",nullable = false)
private String lastName;

@Column(name = "gender",nullable = false)
private String gender;

@Column(name = "dateOfBirth",nullable = false)
private Date dateOfBirth;

@Column(name = "age",nullable = false)
private Byte age;

@Column(name = "createdDate",nullable = false)
private Timestamp createdDate;

@Column(name = "lastUpdatedDate",nullable = false)
private Timestamp lastUpdateDate;

public Person() 
{
    // TODO Auto-generated constructor stub
}
//and setters / getters 
}

DB Create table script :-

CREATE TABLE person
(
  id bigint NOT NULL,
  age smallint NOT NULL,
  createddate timestamp without time zone NOT NULL,
  dateofbirth date NOT NULL,
  firstname character varying(255) NOT NULL,
  gender character varying(255) NOT NULL,
  lastname character varying(255) NOT NULL,
  lastupdateddate timestamp without time zone NOT NULL,
  middlename character varying(255) NOT NULL,
  userid bigint,
  CONSTRAINT person_pkey PRIMARY KEY (id),
  CONSTRAINT fkd8ja1o2m8k25sf0mxvhu4c0ti FOREIGN KEY (userid)
  REFERENCES users (user_id) MATCH SIMPLE
  ON UPDATE NO ACTION ON DELETE NO ACTION
)
WITH (
  OIDS=FALSE
);
ALTER TABLE person
  OWNER TO root;

Table with changed column name :-

CREATE TABLE person
(
  id bigint NOT NULL,
  age smallint NOT NULL,
  "createdDate" timestamp without time zone NOT NULL,
  dateofbirth date NOT NULL,
  firstname character varying(255) NOT NULL,
  gender character varying(255) NOT NULL,
  lastname character varying(255) NOT NULL,
  lastupdateddate timestamp without time zone NOT NULL,
  middlename character varying(255) NOT NULL,
  userid bigint,
  CONSTRAINT person_pkey PRIMARY KEY (id),
  CONSTRAINT fkd8ja1o2m8k25sf0mxvhu4c0ti FOREIGN KEY (userid)
  REFERENCES users (user_id) MATCH SIMPLE
  ON UPDATE NO ACTION ON DELETE NO ACTION
)
WITH (
  OIDS=FALSE
);
ALTER TABLE person
  OWNER TO root;

Now I restart server and new error occurred :-

Feb 21, 2017 11:26:07 AM org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 1572 ms
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/D:/sts-bundle/pivotal-tc-server- developer-3.2.2.RELEASE/base-instance/wtpwebapps/FeePaymentPortal/WEB-INF/lib/slf4j-log4j12-1.6.6.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/D:/sts-bundle/pivotal-tc-server-developer-3.2.2.RELEASE/base-instance/wtpwebapps/FeePaymentPortal/WEB-INF/lib/slf4j-simple-1.7.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [org.slf4j.impl.Log4jLoggerFactory]
INFO : org.springframework.web.context.ContextLoader - Root WebApplicationContext: initialization started
INFO : org.springframework.web.context.support.XmlWebApplicationContext - Refreshing Root WebApplicationContext: startup date [Tue Feb 21 11:26:11 IST 2017]; root of context hierarchy
INFO : org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/root-context.xml]
INFO : org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/security-context.xml]
INFO : org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
WARN : org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl - HHH000402: Using Hibernate built-in connection pool (not for production use!)
ERROR: org.hibernate.tool.hbm2ddl.SchemaExport - HHH000389: Unsuccessful: alter table role drop constraint FKgg3583634e0ydkacyk8wbbm19
ERROR: org.hibernate.tool.hbm2ddl.SchemaExport - ERROR: relation "role" does not exist
ERROR: org.hibernate.tool.hbm2ddl.SchemaExport - HHH000389: Unsuccessful: alter table user_roles drop constraint FKhfh9dx7w3ubf1co1vdev94g3f
ERROR: org.hibernate.tool.hbm2ddl.SchemaExport - ERROR: relation "user_roles" does not exist
INFO : org.springframework.web.context.ContextLoader - Root WebApplicationContext: initialization completed in 7665 ms
INFO : org.springframework.web.servlet.DispatcherServlet - FrameworkServlet 'appServlet': initialization started
INFO : org.springframework.web.context.support.XmlWebApplicationContext -  Refreshing WebApplicationContext for namespace 'appServlet-servlet': startup date [Tue Feb 21 11:26:18 IST 2017]; parent: Root WebApplicationContext
INFO : org.springframework.beans.factory.xml.XmlBeanDefinitionReader - Loading XML bean definitions from ServletContext resource [/WEB-INF/spring/appServlet/servlet-context.xml]
INFO : org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor - JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.home(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/payment-month],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.paymentMonth(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/payment-type],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.paymentMethod(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/payment-verified],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.paymentVerified(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/student-fees],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.getStudentFees(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping - Mapped "{[/student-details],methods=[GET]}" onto public java.lang.String org.giks.controllers.HomeController.getStudentDetails(org.springframework.ui.ModelMap)
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter - Looking for @ControllerAdvice: WebApplicationContext for namespace 'appServlet-servlet': startup date [Tue Feb 21 11:26:18 IST 2017]; parent:  Root WebApplicationContext
INFO : org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter - Looking for @ControllerAdvice: WebApplicationContext for namespace 'appServlet-servlet': startup date [Tue Feb 21 11:26:18 IST 2017]; parent: Root WebApplicationContext
INFO : org.springframework.web.servlet.handler.SimpleUrlHandlerMapping - Mapped URL path [/resources/**] onto handler 'org.springframework.web.servlet.resource.ResourceHttpRequestHandler#0'
INFO : org.springframework.web.servlet.DispatcherServlet - FrameworkServlet 'appServlet': initialization completed in 2426 ms
Feb 21, 2017 11:26:21 AM org.apache.catalina.startup.Catalina start
INFO: Server startup in 14090 ms

Answer 1

I believe the main issue is that PostgreSQL column names are not case-sensitive (and it converts unquoted column names to lowercase by default), but Hibernate is.

So for example with your original createddate column:

• Your domain class specifies createdDate, capital D.
• Your table uses createddate, lowercase D.
• Hibernate, when attempting to update the schema (hibernate.hbm2ddl.auto=update), looks for a column named createdDate as specified in the domain class, does not find one because "createddate" != "createdDate", case-sensitive, and so believes the column needs to be added and attempts to do that.
• The add operation fails, because a column with an equivalent name, according to PostgreSQL (case-insensitive) exists.

So your options there are:

1. Specify lowercase column names in your domain class, or
2. Ensure that the column names in the table use matching case, noting that you must quote the column name in column creation statements to get it to preserve case.

As you saw, when you changed your table column name manually to createdDate, it solved that first error (thus exposing a new one).

As for your new error regarding "relation ... does not exist", I'm not entirely sure but I think that this is also connected to case-sensitivity issues in table names, you'll have to investigate further. At least, that's one possibility.

I don't use PostgreSQL enough with Hibernate to know if there's any easier option, e.g. some dialect options or something somewhere to make them play nice together.