Hi,
I don't understand why hibernate needs:
- to make a select SQL command before inserting the data,
- to make an update SQL command after inserting the data.
____________
| Car |
------------------
| id |
|fatherCar |
|firstSonCar |
|nextSiblingCar |
------------------
I intialize the first car, the second car and the father car like this:
O father car: id=[0] firstSonId=[1]
/ \
/ O second car: id=[0] fatherId=[0]
O
first car: id=[1] fatherId=[0] nextSiblingId=[1]
Why hibernate make 'select' and 'update' SQL command, and not just 'insert' ?
How to ban the 'select' and the 'insert'?
Should i change the relationnal mapping?
Should i set a property and which property?
Thanks.
*************************************************************
Hibernate version: 3.0.5
*************************************************************
Mapping documents:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="samples.domain.Car"
table="T_CAR"
dynamic-update="false"
dynamic-insert="false"
select-before-update="false"
optimistic-lock="version"
>
<cache usage="read-write" />
<id
name="id"
column="CAR_ID"
type="java.lang.Integer"
>
<generator class="assigned" />
</id>
<property
name="content"
type="java.lang.String"
update="true"
insert="true"
access="property"
column="CAR_CONTENT"
/>
<!-- unidirectionnal association one-to-one with the father car -->
<many-to-one
name="fatherCar"
class="samples.domain.Car"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="CAR_FATHER_ID"
not-null="false"
lazy="true"
/>
<!-- unidirectionnal association one-to-one with the next sibling car -->
<many-to-one
name="nextSiblingCar"
class="samples.domain.Car"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="CAR_NEXTSIBLING_ID"
not-null="false"
lazy="true"
/>
<!-- unidirectionnal association one-to-one with the first son car -->
<many-to-one
name="firstSonCar"
class="samples.domain.Car"
cascade="none"
outer-join="auto"
update="true"
insert="true"
access="property"
column="CAR_FIRSTSON_ID"
not-null="false"
lazy="true"
/>
</class>
</hibernate-mapping>
*************************************************************
Code between sessionFactory.openSession() and session.close():
Main:
------
Car fatherCar = new Car();
fatherCar.setId(new Integer(0));
fatherCar.setContent(" Father car");
Car firstCar = new Car();
firstCar.setId(new Integer(1));
firstCar.setContent(" first car");
Car secondCar = new Car();
secondCar.setId(new Integer(2));
secondCar.setContent(" second car");
//
fatherCar.setFirstSonCar(firstCar);
//
firstCar.setFatherCar(fatherCar);
firstCar.setNextSiblingCar(secondCar);
//
secondCar.setFatherCar(fatherCar);
// save first car
PersistenceManager.getUniqueInstance().saveCar(firstCar);
// save second car
PersistenceManager.getUniqueInstance().saveCar(secondCar);
// save father car
PersistenceManager.getUniqueInstance().saveCar(fatherCar);
PersistenceManager.getUniqueInstance().closeSession();
*****************************************
Persistence Manager:
-------------------------
package samples;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import samples.domain.Car;
import samples.domain.SteeringWheel;
public class PersistenceManager {
/**
* Logger for this class
*/
private static final Logger _logger = Logger
.getLogger(PersistenceManager.class);
/**
* Hibernate session factory
*/
private SessionFactory _sessionFactory;
/**
* Hibernate session
*/
private Session _session;
/**
* Transaction
*/
private Transaction _tx;
/**
* The unique instance of PersistenceManager class
*/
private static PersistenceManager _uniqueInstance;
/**
* Default constructor
*/
private PersistenceManager() {
super();
// Load hibernate configuration
Configuration cfg = new Configuration();
cfg.configure();
_sessionFactory = cfg.buildSessionFactory();
_session = _sessionFactory.openSession();
_tx = _session.beginTransaction();
}
/**
* @return the unique instance of PersistenceManager
*/
public static PersistenceManager getUniqueInstance() {
if (null == _uniqueInstance) {
_uniqueInstance = new PersistenceManager();
}
return _uniqueInstance;
}
public void saveCar(Car car) {
_logger.debug(" -> saveCar() ");
_session.save(car);
_session.flush();
_tx.commit();
}
public void saveSteeringWheel(SteeringWheel pSteeringWheel) {
_logger.debug(" -> saveSteeringWheel() ");
_session.save(pSteeringWheel);
_session.flush();
_tx.commit();
}
/**
* close the session close the session factory
*/
public void closeSession() {
_session.flush();
_tx.commit();
_session.clear();
_session.close();
_sessionFactory.close();
}
}
*************************************************************
Name and version of the database you are using:
postgresql 8 on XP SP2
*************************************************************
The generated SQL (show_sql=true):
stdout trace:
-------------
12:32:10,314 DEBUG (main) [hibernate.SQL] - select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?
12:32:10,384 DEBUG (main) [hibernate.SQL] - select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?
12:32:10,404 DEBUG (main) [hibernate.SQL] - insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)
12:32:10,424 DEBUG (main) [hibernate.SQL] - update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?
12:32:10,444 DEBUG (main) [hibernate.SQL] - insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)
12:32:10,444 DEBUG (main) [hibernate.SQL] - update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?
12:32:10,454 DEBUG (main) [hibernate.SQL] - insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)
12:32:10,454 INFO (main) [samples.Main] - Time elapsed=[1763 ms]
p6spy trace:
-------------
12:32:09,332|-1||debug||this is com.p6spy.engine.spy.P6SpyDriver@3afb99 and passthru is org.postgresql.Driver@11e67ac
12:32:10,384|40|1|statement|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=0
12:32:10,384|0|1|result|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=0
12:32:10,384|0|1|statement|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=2
12:32:10,384|0|1|result|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=?|select car_."CAR_ID", car_."CAR_CONTENT" as CAR2_0_, car_."CAR_STEERINGWHEEL_ID" as CAR3_0_, car_."CAR_FATHER_ID" as CAR4_0_, car_."CAR_NEXTSIBLING_ID" as CAR5_0_, car_."CAR_FIRSTSON_ID" as CAR6_0_ from "T_CAR" car_ where car_."CAR_ID"=2
12:32:10,404|0|1|batch|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' first car', '', '', '', '', 1)
12:32:10,404|0|1|statement|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' first car', '', '', '', '', 1)
12:32:10,434|0|1|batch|update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?|update "T_CAR" set "CAR_CONTENT"=' first car', "CAR_STEERINGWHEEL_ID"='', "CAR_FATHER_ID"=0, "CAR_NEXTSIBLING_ID"=2, "CAR_FIRSTSON_ID"='' where "CAR_ID"=1
12:32:10,444|0|1|statement|update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?|update "T_CAR" set "CAR_CONTENT"=' first car', "CAR_STEERINGWHEEL_ID"='', "CAR_FATHER_ID"=0, "CAR_NEXTSIBLING_ID"=2, "CAR_FIRSTSON_ID"='' where "CAR_ID"=1
12:32:10,444|0|1|commit||
12:32:10,444|0|1|batch|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' second car', '', '', '', '', 2)
12:32:10,444|0|1|statement|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' second car', '', '', '', '', 2)
12:32:10,454|10|1|batch|update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?|update "T_CAR" set "CAR_CONTENT"=' second car', "CAR_STEERINGWHEEL_ID"='', "CAR_FATHER_ID"=0, "CAR_NEXTSIBLING_ID"='', "CAR_FIRSTSON_ID"='' where "CAR_ID"=2
12:32:10,454|0|1|statement|update "T_CAR" set "CAR_CONTENT"=?, "CAR_STEERINGWHEEL_ID"=?, "CAR_FATHER_ID"=?, "CAR_NEXTSIBLING_ID"=?, "CAR_FIRSTSON_ID"=? where "CAR_ID"=?|update "T_CAR" set "CAR_CONTENT"=' second car', "CAR_STEERINGWHEEL_ID"='', "CAR_FATHER_ID"=0, "CAR_NEXTSIBLING_ID"='', "CAR_FIRSTSON_ID"='' where "CAR_ID"=2
12:32:10,454|0|1|commit||
12:32:10,454|0|1|batch|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' Father car', '', '', '', 1, 0)
12:32:10,454|0|1|statement|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (?, ?, ?, ?, ?, ?)|insert into "T_CAR" ("CAR_CONTENT", "CAR_STEERINGWHEEL_ID", "CAR_FATHER_ID", "CAR_NEXTSIBLING_ID", "CAR_FIRSTSON_ID", "CAR_ID") values (' Father car', '', '', '', 1, 0)
12:32:10,454|0|1|commit||
12:32:10,454|0|1|commit||
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