The document discusses several techniques for optimizing GORM performance: 1. Mapping database views to domain classes to avoid unnecessary joins. 2. Writing a custom configuration subclass to filter DDL statements or override Hibernate behavior. 3. Implementing read-only domain classes by preventing saves, deletes, and updates through event listeners. 4. Monitoring SQL queries through logging, plugins, and timing analysis to identify optimization opportunities.

1. GORM Optimization
Burt Beckwith
SpringSource
CONFIDENTIAL
© 2010 SpringSource, A division of VMware. All rights reserved

2. Agenda
 Mapping Database Views
 Writing a Custom Configuration Subclass for Fun and Profit
 Read-only Domain Classes
 Monitoring
CONFIDENTIAL 2

3. Also See
 Advanced GORM - Performance, Customization and
Monitoring
• Spring One / class UserInfo {
2GX 2010
String name
String orgName
• http://www.infoq.com/presentations/GORM-Performance
static mapping = {
• Primarily focused on 'v_user_info'
table performance implications around
}
}
using Many-to-One and Many-to-Many in GORM
CONFIDENTIAL 3

4. Mapping Database Views
CONFIDENTIAL 4

5. Database View –> Entity
class Organization {
String name
}
class UserInfo {
String name
String orgName
}
class AuthUser {
String name
String password
Organization organization
}
CONFIDENTIAL 5

6. Database View –> Entity
CREATE OR REPLACE VIEW v_user_info AS
SELECT u.name, u.id, u.version, o.name org_name
FROM auth_user u, organization o
WHERE u.organization_id = o.id
class UserInfo {
String name
String orgName
static mapping = {
table 'v_user_info'
}
}
CONFIDENTIAL 6

7. Database View –> Entity
ERROR hbm2ddl.SchemaExport ­
Unsuccessful: create table v_user_info (id
bigint not null auto_increment, version
bigint not null, name varchar(255) not
null, org_name varchar(255) not null,
primary key (id)) type=InnoDB
ERROR hbm2ddl.SchemaExport ­ Table
'v_user_info' already exists
CONFIDENTIAL 7

8. Database View –> Entity
Register a Custom Configuration in DataSource.groovy
dataSource {
pooled = true
driverClassName = ...
username = ...
password = ...
dialect = ...
configClass = gr8conf.DdlFilterConfiguration
}
CONFIDENTIAL 8

9. Database View –> Entity
public class DdlFilterConfiguration extends GrailsAnnotationConfiguration {
private static final String[] IGNORED_NAMES = { "v_user_info" };
...
private boolean isIgnored(String command) {
command = command.toLowerCase();
for (String table : IGNORED_NAMES) {
if (command.startsWith("create table " + table + " ") ||
command.startsWith("alter table " + table + " ") ||
command.startsWith("drop table " + table) ||
command.startsWith("drop table if exists " + table)) {
return true;
}
}
return false;
}
}
CONFIDENTIAL 9

10. Database View –> Entity
grails-app/conf/hibernate/hibernate.cfg.xml
<hibernate­configuration>
<session­factory>
<mapping resource='misc.mysql.innodb.hbm.xml'/>
<mapping resource='misc.h2.hbm.xml'/>
</session­factory>
</hibernate­configuration>
CONFIDENTIAL 10

11. Database View –> Entity
grails-app/conf/hibernate/misc.mysql.innodb.hbm.xml
<hibernate­mapping>
<database­object>
<create>
CREATE OR REPLACE VIEW v_user_info AS
SELECT u.name, u.id, u.version, o.name org_name
FROM auth_user u, organization o
WHERE u.organization_id = o.id
</create>
<drop>DROP VIEW IF EXISTS v_user_info</drop>
<dialect­scope
name='org.hibernate.dialect.MySQLInnoDBDialect' />
</database­object>
</hibernate­mapping>
CONFIDENTIAL 11

12. Subdomain Entity
“Subdomain” with a subset of AuthUser data:
class Person {
String name
Organization organization
static mapping = {
table 'auth_user'
}
}
CONFIDENTIAL 12

13. Subdomain Entity
Updatable Subdomain:
class Person {
String name
Organization organization
static mapping = {
table 'auth_user'
dynamicUpdate true
}
}
CONFIDENTIAL 13

14. Writing a Custom Configuration Subclass for
Fun and Profit
CONFIDENTIAL 14

15. Writing a Custom Configuration Subclass for Fun and Profit
Custom Configurations: http://burtbeckwith.com/blog/?p=465
 Examples
• Previous SQL generation example
• Overrides generateSchemaCreationScript(),
generateDropSchemaScript(), and generateSchemaUpdateScript()
• Specifying the 'connection.provider_class' property
• Overrides buildSettings()
• Renaming columns of a composite foreign key
• Overrides secondPassCompile()
• Overriding the EntityPersister class
• Overrides secondPassCompile()
• Using field access
• Overrides secondPassCompile()
CONFIDENTIAL 15

16. Writing a Custom Configuration Subclass for Fun and Profit
 secondPassCompile()
• Access each PersistentClass/RootClass and call any of
• addFilter() • setDynamicUpdate()
• setBatchSize() • setExplicitPolymorphism()
• setCustomSQLDelete() • setOptimisticLockMode()
• setCustomSQLInsert() • setSelectBeforeUpdate()
• setCustomSQLUpdate() • setWhere()
• setDynamicInsert()
CONFIDENTIAL 16

17. Read-only Domain Classes
CONFIDENTIAL 17

18. Read-only Domain Classes
 Not 100% possible, but close enough
 Hibernate
• Seems possible via setMutable(false) in a custom Configuration, but:
• Won't block saves or deletes, only disables dirty-check updates
• Does nothing with collections since they're a PersistentSet or
PersistentList and managed separately (but you wouldn't want to map
collections anyway, right?)
• See http://docs.jboss.org/hibernate/core/3.5/reference/en/html/readonly.html
CONFIDENTIAL 18

19. Read-only Domain Classes
 Grails
• Only beforeUpdate supports 'vetoing' by returning false
• A hackish solution would be to throw an exception in beforeDelete and
beforeInsert
• Better solution: hibernateEventListeners bean in grails­
app/conf/spring/resources.groovy
• Still a good idea to use a custom Configuration and call setMutable(false)
to reduce memory usage
CONFIDENTIAL 19

20. Read-only Domain Classes
grails-app/conf/spring/resources.groovy
import gr8conf.ReadOnlyEventListener
import o.c.g.g.orm.hibernate.HibernateEventListeners
beans = {
readOnlyEventListener(ReadOnlyEventListener)
hibernateEventListeners(HibernateEventListeners) {
listenerMap = ['pre­delete': readOnlyEventListener,
'pre­insert': readOnlyEventListener,
'pre­update': readOnlyEventListener]
}
}
CONFIDENTIAL 20

21. Read-only Domain Classes
src/groovy/gr8conf/ReadOnlyEventListener.groovy
class ReadOnlyEventListener implements PreDeleteEventListener,
PreInsertEventListener, PreUpdateEventListener {
private static final List<String> READ_ONLY = ['gr8conf.LegacyData']
boolean onPreDelete(PreDeleteEvent event) {
isReadOnly event.persister.entityName
}
boolean onPreInsert(PreInsertEvent event) {
isReadOnly event.persister.entityName
}
boolean onPreUpdate(PreUpdateEvent event) {
isReadOnly event.persister.entityName
}
private boolean isReadOnly(String name) { READ_ONLY.contains name }
}
CONFIDENTIAL 21

22. Read-only Domain Classes
grails-app/domain/gr8conf/LegacyData.groovy
class LegacyData {
String name
static mapping = {
id column: 'legacy_data_id'
version false
}
}
CONFIDENTIAL 22

23. Read-only Domain Classes
 ReadOnlyEventListener
• delete()
• silently fails
• Update with save()
• silently fails
• New instance save()
• Throws exception ?
CONFIDENTIAL 23

24. Read-only Domain Classes
You can also map a second writable domain class
to the same table, e.g. for admin:
class User { class WritableUser {
String username String username
String password String password
}
static mapping = {
table 'user'
}
}
CONFIDENTIAL 24

25. Monitoring
CONFIDENTIAL 25

26. Monitoring
 SQL logging
• logSql=true in DataSource.groovy
• org.hibernate.SQL → debug, org.hibernate.type → trace
appenders {
file name: 'sql', file: 'sql.log'
}
debug additivity: false, sql: 'org.hibernate.SQL'
trace additivity: false, sql: 'org.hibernate.type'
• P6spy plugin
• Use SQL Profiler Swing app to view realtime logs; see Mike Hugo's blog post
Grails, p6spy and Sql Profiler
• Run explain (Oracle, MySQL, others) on real queries to look for missing indexes
CONFIDENTIAL 26

27. Monitoring
 Spring Insight lets you drill down to SQL and view timing
• http://www.grails.org/screencast/show/13
 Profiler plugin can give you timing data
 JavaMelody Plugin
 App Info plugin
CONFIDENTIAL 27

28. Questions?
CONFIDENTIAL 28