不成功：在 Hibernate/JPA/HSQLDB 独立中更改表 XXX 删除约束 YYY

Question

我正在尝试使用内存中的 HSQL DB 运行一些 Hibernate/JPA 示例。我得到的错误信息如下：

13:54:21,427 ERROR SchemaExport:425 - HHH000389: Unsuccessful: alter table ReferringItem_map drop constraint FK5D4A98E0361647B8
13:54:21,427 ERROR SchemaExport:426 - user lacks privilege or object not found: PUBLIC.REFERRINGITEM_MAP
13:54:21,427 ERROR SchemaExport:425 - HHH000389: Unsuccessful: alter table ReferringItem_myCollection drop constraint FK75BA3266361647B8
13:54:21,427 ERROR SchemaExport:426 - user lacks privilege or object not found: PUBLIC.REFERRINGITEM_MYCOLLECTION
13:54:21,428 ERROR SchemaExport:425 - HHH000389: Unsuccessful: alter table ReferringItem_myList drop constraint FK6D37AA66361647B8
13:54:21,428 ERROR SchemaExport:426 - user lacks privilege or object not found: PUBLIC.REFERRINGITEM_MYLIST
13:54:21,428 ERROR SchemaExport:425 - HHH000389: Unsuccessful: alter table ReferringItem_mySet drop constraint FK3512699A361647B8
13:54:21,429 ERROR SchemaExport:426 - user lacks privilege or object not found: PUBLIC.REFERRINGITEM_MYSET

对应的类是：

@Entity
public class ReferringItem implements Serializable {

    @Id
    private long id;

    @ElementCollection
    private Collection<AnEmbeddable> myCollection
        = new ArrayList<AnEmbeddable>();

    @ElementCollection(fetch=FetchType.EAGER)
    private Set<Long> mySet = new HashSet<Long>();

    @ElementCollection(targetClass=String.class)
    private List myList = new ArrayList();

    @ElementCollection
    private Map<String,AnEmbeddable> map
        = new HashMap<String,AnEmbeddable>();

    public ReferringItem() { }

    // Setters & Getters

}

可嵌入的是：

@Embeddable
public class AnEmbeddable implements Serializable {

    private String s;

    public AnEmbeddable() { }

    public String getS() {
        return s;
    }

    public void setS(String s) {
        this.s = s;
    }

}

我的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="JPA" transaction-type="RESOURCE_LOCAL">

        <provider>org.hibernate.ejb.HibernatePersistence</provider>

        <class>com.jverstry.jpa.AuthorizedTypes.AuthorizedTypes</class>
        <class>com.jverstry.jpa.AuthorizedTypes.OtherEntity</class>
        <class>com.jverstry.jpa.AuthorizedTypes.SomeEmbeddable</class>

        <properties>
            <property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver"/>
            <property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:mem:testdb"/>
            <property name="javax.persistence.jdbc.user" value="sa"/>
            <property name="javax.persistence.jdbc.password" value=""/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
        </properties>

    </persistence-unit>

</persistence>

我在休眠 4.1.5.Final 和 HSQLDB 2.2.8。

有谁知道是什么导致了这个问题以及如何解决它？

Answer 1

您可以忽略这些错误。 create-drop 和空（内存中的情况总是如此）数据库的组合会为它尝试删除的每个数据库对象生成这些。原因是没有要删除的任何数据库对象 - DROP 语句是针对空数据库执行的。

对于普通的永久数据库也会出现这样的错误，因为在执行 DROP 语句之前，Hibernate 没有弄清楚添加的对象是否存在于数据库中或者是新的。

Answer 2

这个解决方案对我有用，与给出的其他解决方案相反。显然里程有所不同。

这是我的确切错误：

HHH000389: Unsuccessful: alter table ... drop constraint FK_g1uebn6mqk9qiaw45vnacmyo2 if exists
Table "..." not found; SQL statement: ...

这是我的解决方案，覆盖 H2 方言：

package com.totaalsoftware.incidentmanager;

import org.hibernate.dialect.H2Dialect;

/**
 * Workaround.
 * 
 * @see https://hibernate.atlassian.net/browse/hhh-7002
 * 
 */
public class ImprovedH2Dialect extends H2Dialect {
    @Override
    public String getDropSequenceString(String sequenceName) {
        // Adding the "if exists" clause to avoid warnings
        return "drop sequence if exists " + sequenceName;
    }

    @Override
    public boolean dropConstraints() {
        // We don't need to drop constraints before dropping tables, that just
        // leads to error messages about missing tables when we don't have a
        // schema in the database
        return false;
    }
}

Answer 3

上面提供的@Sander 解决方案也适用于 MYSQL。只需扩展 MySQL5InnoDBDialect，如下所示：

import org.hibernate.dialect.MySQL5InnoDBDialect;

public class ImprovedMySQLDialect extends MySQL5InnoDBDialect {
    @Override
    public String getDropSequenceString(String sequenceName) {
        // Adding the "if exists" clause to avoid warnings
        return "drop sequence if exists " + sequenceName;
    }

    @Override
    public boolean dropConstraints() {
        // We don't need to drop constraints before dropping tables, that just leads to error
        // messages about missing tables when we don't have a schema in the database
        return false;
    }
}

然后在您的数据源文件中更改以下行：

dialect = org.hibernate.dialect.MySQL5InnoDBDialect

到

dialect = my.package.name.ImprovedMySQLDialect

Answer 4

只需设置dbCreate="update"，错误就会立即消失。

见：https://stackoverflow.com/a/31257468/715608

Answer 5

在每次使用带有 HSQLDB 和 hbm2ddl.auto=create-drop 的内存数据库的测试开始时，烦人的错误消息变得更加令人讨厌。

对HSQLDB bug report 的回复建议使用 DROP TABLE ... CASCADE 而不是 DROP CONSTRAINT IF EXISTS。不幸的是，删除表的 HSQLDB 语法是 DROP TABLE <table> [IF EXISTS] [RESTRICT | CASCADE]; Hibernate Dialect 没有为方言提供一种简单的机制来在最后的 IF EXISTS 子句之后指定 CASCADE。我为这个限制写了a bug。

但是，我能够通过创建如下自定义方言来克服这个问题：

public class HsqlDialectReplacement extends HSQLDialect {

  @Override
  public String getDropTableString( String tableName ) {
    // Append CASCADE to formatted DROP TABLE string
    final String superDrop = super.getDropTableString( tableName );
    return superDrop + " cascade";
  }

  @Override
  public boolean dropConstraints() {
      // Do not explicitly drop constraints, use DROP TABLE ... CASCADE
      return false;
  }

  @Override
  public Exporter<Table> getTableExporter() {
    // Must override TableExporter because it also formulates DROP TABLE strings
    synchronized( this ) {
      if( null == overrideExporter ) {
        overrideExporter = new HsqlExporter( super.getTableExporter() );
      }
    }

    return overrideExporter;
  }

  private Exporter<Table> overrideExporter = null;

  private static class HsqlExporter implements Exporter<Table> {
    HsqlExporter( Exporter<Table> impl ) {
      this.impl = impl;
    }

    @Override
    public String[] getSqlCreateStrings( Table exportable, Metadata metadata ) {
      return impl.getSqlCreateStrings( exportable, metadata );
    }

    @Override
    public String[] getSqlDropStrings( Table exportable, Metadata metadata ) {
      final String[] implDrop = impl.getSqlDropStrings( exportable, metadata );
      final String[] dropStrings = new String[implDrop.length];
      for( int i=0; i<implDrop.length; ++i ) {
        dropStrings[i] = implDrop[i] + " cascade";
      }
      return dropStrings;
    }

    private final Exporter<Table> impl;
  };
}

Answer 6

我们在尝试在Spring 中创建一个简单的登录窗口时遇到了同样的问题。有两个表user 和role，主键id 类型为BIGINT。我们将这些 (Many-to-Many) 映射到另一个表 user_roles，其中两列 user_id 和 role_id 作为外键。

问题是user_roles 表中的role_id 列，它属于int 类型，并且与role 的外键不兼容。当类型修改为BIGINT时，错误已被纠正。