使用Grails进行Hibernate和postgreSQL

Question

有一种简单的方法可以将hibernate设置为使用postgres为每个表使用不同的主键ID吗？我试图在DataSource中使用postgres方言:

dialect = org.hibernate.dialect.PostgreSQLDialect 
or
dialect = net.sf.hibernate.dialect.PostgreSQLDialect

但它不起作用.谢谢

Answer 1

简短的回答是否定的,没有一种简单的方法可以做到这一点.但是,我找到了一个可行的解决方案.基本上你需要实现一个自定义方言.这是一个实现(请注意评论中的实现的原始来源).

package com.my.custom;

import java.util.Properties;

import org.hibernate.dialect.Dialect;
import org.hibernate.dialect.PostgreSQLDialect;
import org.hibernate.id.PersistentIdentifierGenerator;
import org.hibernate.id.SequenceGenerator;
import org.hibernate.type.Type;


/**
 * Creates a sequence per table instead of the default behavior of one sequence.
 *
 * From <a href='http://www.hibernate.org/296.html'>http://www.hibernate.org/296.html</a>
 * @author Burt
 */
public class TableNameSequencePostgresDialect extends PostgreSQLDialect {

    /**
     * Get the native identifier generator class.
     * @return TableNameSequenceGenerator.
     */
    @Override
    public Class<?> getNativeIdentifierGeneratorClass() {
            return TableNameSequenceGenerator.class;
    }

    /**
     * Creates a sequence per table instead of the default behavior of one sequence.
     */
    public static class TableNameSequenceGenerator
           extends SequenceGenerator {

            /**
             * {@inheritDoc}
             * If the parameters do not contain a {@link SequenceGenerator#SEQUENCE} name, we
             * assign one based on the table name.
             */
            @Override
            public void configure(
                            final Type type,
                            final Properties params,
                            final Dialect dialect) {
                    if (params.getProperty(SEQUENCE) == null
                                    || params.getProperty(SEQUENCE).length() == 0) {
                            String tableName = params.getProperty(PersistentIdentifierGenerator.TABLE);
                            if (tableName != null) {
                                    params.setProperty(SEQUENCE, "seq_" + tableName);
                            }
                    }
                    super.configure(type, params, dialect);
            }
    }

}

上述实施应当存储为TableNameSequencePostgresDialect.java下src/java/com/my/custom你的Grails项目中.

接下来,更新您DataSource.groovy的使用这个新的自定义方言.

dialect = com.my.custom.TableNameSequencePostgresDialect

这几乎就是它.不容易,但可以做到.