我正在将应用程序从Hibernate 4.3迁移到Hibernate 5.0.1-Final
我使用ImplicitNamingStrategyComponentPathImpl作为我的hibernate.implicit_naming_strategy和Postgres 9.4.4，我的公司使用hibernate.hbm2ddl.auto = update进行部署（我知道这是一种不好的做法，但无法帮助它）
会话工厂初始化时，会抛出以下错误。显然，为Postgres生成的别名太长了。我们如何处理这种情况？我已经尝试分配@Table(name=..)注释来解决这个问题，但是随着每个关系从那一点开始变得困难，它会变得更糟。
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [create table public.ReferenceDocumentVersion_ReferenceDocumentSourceFilesStoreDescriptor (ReferenceDocumentVersion_unid uuid not null, sourceFilesStore_filesDescriptorMap_unid uuid not null, filesDescriptorMap_KEY text not null, primary key (ReferenceDocumentVersion_unid, filesDescriptorMap_KEY))]
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:371)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:360)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.createTable(SchemaMigratorImpl.java:181)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:134)
at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:59)
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)
... 29 more
Caused by: org.postgresql.util.PSQLException: ERROR: relation "referencedocumentversion_referencedocumentsourcefilesstoredescr" already exists
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2182)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1911)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:173)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:618)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:454)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeUpdate(AbstractJdbc2Statement.java:382)
at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228)
at org.apache.tomcat.dbcp.dbcp.DelegatingStatement.executeUpdate(DelegatingStatement.java:228)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.bull.javamelody.JdbcWrapper.doExecute(JdbcWrapper.java:404)
at net.bull.javamelody.JdbcWrapper$StatementInvocationHandler.invoke(JdbcWrapper.java:129)
at net.bull.javamelody.JdbcWrapper$DelegatingInvocationHandler.invoke(JdbcWrapper.java:286)
at com.sun.proxy.$Proxy93.executeUpdate(Unknown Source)
at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56)
... 39 more
答案 0 :(得分：4)
我用自定义ImplicitNamingStrategy解决了这种情况，它将Hibernate生成的标识符截断为64个字符（Postgres的MAX长度）。
以前版本的Hibernate（4.x）遇到了同样的错误，但它们只是忽略它并继续初始化SessionFactory。但是，Hibernate 5.x有一个新的引导程序API，在这种情况下会抛出SchemaManagementException并中止。我的测试场景中的Hibernate日志粘贴在下面以供参考。
Hibernate 4.X
INFO: HHH000396: Updating schema
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.DatabaseMetadata getTableMetadata
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
ERROR: HHH000388: Unsuccessful: create table ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres (unid uuid not null, path text, primary key (unid))
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
ERROR: ERROR: relation "referencedocumentversionentitywithareallyreallyreallylongnamebe" already exists
Oct 04, 2015 1:38:00 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
INFO: HHH000232: Schema update complete
Hibernate 5.0.2.Final
Oct 04, 2015 1:39:16 PM org.hibernate.tool.hbm2ddl.SchemaUpdate execute
INFO: HHH000228: Running hbm2ddl schema update
Oct 04, 2015 1:39:16 PM org.hibernate.tool.schema.extract.internal.InformationExtractorJdbcDatabaseMetaDataImpl processGetTableResults
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Oct 04, 2015 1:39:16 PM org.hibernate.tool.schema.extract.internal.InformationExtractorJdbcDatabaseMetaDataImpl processGetTableResults
INFO: HHH000262: Table not found: ReferenceDocumentVersionEntityWithAReallyReallyReallyLongNameBeyondPostGres
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.813 sec <<< FAILURE!
testApp(org.foobar.AppTest) Time elapsed: 0.788 sec <<< ERROR!
javax.persistence.PersistenceException: [PersistenceUnit: org.foobar.persistence.default] 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 org.foobar.AppTest.testApp(AppTest.java:18)
<强>解决方案
自定义ImplicitNamingStrategy
package org.foobar.persistence;
import org.hibernate.boot.model.naming.Identifier;
import org.hibernate.boot.model.naming.ImplicitNamingStrategyComponentPathImpl;
import org.hibernate.boot.spi.MetadataBuildingContext;
public class PGConstrainedImplicitNamingStrategy extends ImplicitNamingStrategyComponentPathImpl {
private static final int POSTGRES_IDENTIFIER_MAXLENGTH = 63;
public static final PGConstrainedImplicitNamingStrategy INSTANCE = new PGConstrainedImplicitNamingStrategy();
public PGConstrainedImplicitNamingStrategy() {
}
@Override
protected Identifier toIdentifier(String stringForm, MetadataBuildingContext buildingContext) {
return buildingContext.getMetadataCollector()
.getDatabase()
.getJdbcEnvironment()
.getIdentifierHelper()
.toIdentifier( stringForm.substring( 0, Math.min( POSTGRES_IDENTIFIER_MAXLENGTH, stringForm.length() ) ) );
}}
的persistence.xml
<properties>
<property name="hibernate.implicit_naming_strategy" value="org.foobar.persistence.PGConstrainedImplicitNamingStrategy"/>
</properties>
这根本不是一个可扩展的解决方案，但有助于保持节目的运行。永久解决方案是以显式提供标识符，以便hibernate不会生成非常长的标识符。 - 请参阅maaartinus所写的答案
答案 1 :(得分：3)
尝试按照此链接中的Hibernate文档中的迁移指南进行操作
https://github.com/hibernate/hibernate-orm/blob/5.0/migration-guide.adoc
答案 2 :(得分：2)
Map<String, String>将所有超长名称映射到更短的内容POSTGRES_IDENTIFIER_MAXLENGTH - N并附加从切除部分的哈希生成的N个字符，以便最大限度地减少碰撞的可能性{"Reference" -> "Ref", "Document" -> "Doc", ...}，并在处理之前将其应用于您的标识符，以便获得RefDocVersion_RefDocSourceFileDescr...而不是referencedocumentversion_referencedocumentsourcefilesstoredescr...。