By default Grails uses Hibernate's ImprovedNamingStrategy to convert domain class Class and field names to SQL table and column names by converting from camel-cased Strings to ones that use underscores as word separators. You can customize these on a per-instance basis in the mapping closure but if there's a consistent pattern you can specify a different NamingStrategy class to use.

Configure the class name to be used in grails-app/conf/DataSource.groovy in the hibernate section, e.g.

dataSource {
    pooled = true
    dbCreate = "create-drop"
	 …
}

hibernate { cache.use_second_level_cache = true … naming_strategy = com.myco.myproj.CustomNamingStrategy }

You can use an existing class or write your own, for example one that prefixes table names and column names:

package com.myco.myproj

import org.hibernate.cfg.ImprovedNamingStrategy import org.hibernate.util.StringHelper

class CustomNamingStrategy extends ImprovedNamingStrategy {

String classToTableName(String className) { "table_" + StringHelper.unqualify(className) }

String propertyToColumnName(String propertyName) { "col_" + StringHelper.unqualify(propertyName) } }