Hibernate & postgreSQL with Grails

Question

There is an easy way to set hibernate to use different primary key ids for each table with postgres? I tried to use postgres dialect in DataSource:

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

But it doesn't work. Thanks

Answer 1

The short answer is no, there isn't a easy way to do this. However, I have found a solution that does work. Basically you need to implement a custom dialect. Here is an implementation (please note the original source of the implementation within the comments).

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);
            }
    }

}

The above implementation is should be stored as TableNameSequencePostgresDialect.java under src/java/com/my/custom within your Grails project.

Next, update your DataSource.groovy to use this new custom dialect.

dialect = com.my.custom.TableNameSequencePostgresDialect

That's pretty much about it. Not easy but it can be done.