EJB + "transaction attributes" + "best practice"

hi
For EJBs, when you specify multiple transaction attributes for a single
method, is the latest attribute taken or the first?
for e.g. In Jbuilder8 in the container transaction section for an EJB,
if i were to put
Method Transaction attribute
* Required
getSomeThing() Supported
As you can see all the methods were initially given the required attribute,
and then the method getSomeThing() was given Supported. will the
getSomething() method use Required or else Supported. Secondly, will this
cause an extra overload (Transaction attributes are set and the again
reset), is it a recommended best practice?
suren

getSomeThing() Supported
As you can see all the methods were initially given
the required attribute,
and then the method getSomeThing() was given
Supported. will the
getSomething() method use Required or else Supported.It will use supported.
Secondly, will this
cause an extra overload (Transaction attributes are
set and the againIt won't cause extra overload.
reset), is it a recommended best practice?It really depends on your needs - what you're trying to achieve. There is no best practice for that it depends on the application you're building.
Regards,
Dimitar

Similar Messages

Ejb Transaction Attribute

We are using Ejbs2.1
Our system uses Database but we are not writing IT System so we do not need To use trasactions at all.
We are using RequiresNew as the Transaction Attribute so every
ejb starts in a new transaction and each method only invoke one database access
We are now considering to change the Transaction Attribute to NotSupported So each database access will do a commit (the database connection is set to autoCommit)
We thought that this approach will be more efficient since no transaction will be created.
I will be happy to hear what you think about this approach, is our assumption is correct?

it means that the method must operate outside of an active transaction - in other words there will be no active transaction during its runtime. If there is an active transaction when the method is called, that transaction is "put on hold" until the "notsupported" EJB call finishes.

Regarding EJB transaction attributes

Hi,
I am having a method in a stateless session bean. This bean's transaction
attribute is "Required'. This method in turn is calling a create method using another entity bean whose transaction attribute is "Required".
After calling the create method we are using another stateless session bean
having transaction attribute "NotSupported" to retrieve the previously created record(We have our own business requirement, that's the reason we are using here another session bean to retrieve immediatly the created record, instead of using the same entity bean). All the above transactions are done in the same method.
while calling the retrive method to retrieve the immediatly created record, we are getting an exception saying the below.
SQL0911N The current transaction has been rolled back because of
a deadlock or timeout. Reason code "68".
What could be the problem? Can anyone help me out?
Note : if we use a different method for the retrieval alone then it's working fine.
Thanks.

The container might have suspended the current transaction, and called the retrieve method whose tx attribute is NotSupported. The duration of this invocation may have exceeded the transaction timeout limit. After the transaction has been left idle for such a long period, it times out.

Is it posible that transaction attribute required & isolation any after no

Dear freind
I want to share this question which i face in a company Rose It Solution Delhi India
que:-- There is a Account EJB transaction attribute is required which isolation level select that there will be no changes in database a) TX_readOnly b) TX_raed_commited c)TX_unreapitable_read d)TX_Serializable After all i think TX_readOnly is not a isolation level second things that is transaction attribute is required then why not changes in database
Regards
Rajesh Pandey freelance Developer e-mail:-- [email protected]
Please use html tags to format code blocks.

Dear freind
I want to share this question which i face in a company Rose It Solution Delhi India
que:-- There is a Account EJB transaction attribute is required which isolation level select that there will be no changes in database a) TX_readOnly b) TX_raed_commited c)TX_unreapitable_read d)TX_Serializable After all i think TX_readOnly is not a isolation level second things that is transaction attribute is required then why not changes in database
Regards
Rajesh Pandey freelance Developer e-mail:-- [email protected]
Please use html tags to format code blocks.

Best practice for Servlet EJB integration

          I'm wondering what the best practice is for Servlet EJB integration in terms of
          caching the home and remote objects. My understanding is that the Home object
          is threadsafe and could therefore be cached as an attribute of the Servlet. This
          would remove the need for a JNDI lookup for each request. Similarly caching the
          ProxyObject would yield further savings. However, I have noticed that most examples
          don't use either of these practices. Why not?
          Thanks in advance,
          Geordie


This has been answered repeatedly. WL allows you to cache JNDI context
          objects, ejb homes and remotes without any problems. (EJB remote interfaces
          must only be used by one thread at a time, but that requirement is provided
          by the EJB spec itself.)
          Peace,
          Cameron Purdy
          Tangosol, Inc.
          http://www.tangosol.com
          +1.617.623.5782
          WebLogic Consulting Available
          "Geordie" <[email protected]> wrote in message
          news:3af9579f$[email protected]..
          >
          > I'm wondering what the best practice is for Servlet EJB integration in
          terms of
          > caching the home and remote objects. My understanding is that the Home
          object
          > is threadsafe and could therefore be cached as an attribute of the
          Servlet. This
          > would remove the need for a JNDI lookup for each request. Similarly
          caching the
          > ProxyObject would yield further savings. However, I have noticed that
          most examples
          > don't use either of these practices. Why not?
          >
          > Thanks in advance,
          > Geordie

Best Practice for Mass Deleting Transactions

Hi Gurus
Can you please guide on this - We need to mass delete Leads from the system. I can use Crm_Order_Delete FM. But want to know if there are any best practices to follow, or anything else that i should consider before deleting these transactions from the system.
We have our archiving policy under discussion which may take some time, but due to large volume of reduntatn data we have some performance issues. For example when searching for leads and using ACE, the system goes through all the lead data.
That is the reason we are plannign to delete those old records. My concerns is that using CRM_ORDER_DELETE, would it clear all the tables for those deleted transactions and if there are any best practices to follow.
Thanks in Advance.
Regards.
-MP
Edited by: Mohanpreet Singh on Apr 15, 2010 5:18 PM

Hi,
Please go through the AppModel application which is available at: http://developers.sun.com/prodtech/javatools/jscreator/reference/codesamples/sampleapps.html
The OnePage Table Based example shows exactly how to use deleting multiple rows from a datatable...
Hope this helps.
Thanks,
RK.

Need advise for best practice when using Toplink with external transaction

Hello;
Our project is trying to switch from Toplink control transaction to using External transaction so we can make database operation and JMS operation within a single transaction.
Some of our team try out the Toplink support for external transaction and come up with the following initial recommendation.
Since we are not familar with using external transaction, I would like member of this forum and experts, to help comment on whether these recommendation are indeed valid or in line with the best practice. And for folks that have done this in their project, what did you do ?
Any help will be most appreciated.
Data Access Objects must be enhanced to support reading from a TOPLink unit of work when using an external transaction controller. Developers must consider what impact a global transaction will have on the methods in their data access objects (DAOs).
The following findSomeObject method is representative of a finder in the current implementation of our DAOs. It is not especially designed to execute in the context of a global transaction, nor read from a unit of work.
public findSomeObject(ILoginUser aUser, Expression queryExpression)
ClientSession clientSession = getClientSession(aUser);
SomeObject obj = null;
try
ReadObjectQuery readObjectQuery = new ReadObjectQuery(SomeObject.class);
readObjectQuery.setSelectionCriteria(queryExpression);
obj = (SomeObject)clientSession.executeQuery(readObjectQuery);
catch (DatabaseException dbe)
// throw an appropriate exception
finally
clientSession.release();
if (obj == null)
// throw an appropriate exception
return obj;
However, after making the following changes (in blue) the findSomeObject method will now read from a unit of work while executing in the context of a global transaction.
public findSomeObject(ILoginUser aUser, Expression queryExpression)
Session session = getClientSession(aUser);
SomeObject obj = null;
try
ReadObjectQuery readObjectQuery = new ReadObjectQuery(SomeObject.class);
readObjectQuery.setSelectionCriteria(queryExpression);
if (TransactionController.getInstance().useExternalTransactionControl())
     session = session.getActiveUnitOfWork();
     readObjectQuery.conformResultsInUnitOfWork(); }
obj = (SomeObject)session.executeQuery(readObjectQuery);
catch (DatabaseException dbe)
// throw an appropriate exception
finally
if (TransactionController.getInstance().notUseExternalTransactionControl())
     session.release();
if (obj == null)
// throw an appropriate exception
return obj;
When getting the TOPLink client session and reading from the unit of work in the context of a global transaction, new objects need to be cached.
public getUnitOfWork(ILoginUser aUser)
throws DataAccessException
     ClientSession clientSession = getClientSession(aUser);
     UnitOfWork uow = null;
     if (TransactionController.getInstance().useExternalTransactionControl())
          uow = clientSession.getActiveUnitOfWork();
          uow.setShouldNewObjectsBeCached(true);     }
     else
          uow = clientSession.acquireUnitOfWork();
     return uow;
}

As it generally is with this sort of question there is no exact answer.
The only required update when working with an External Transaction is that getActiveUnitOfWork() is called instead of acquireUnitOfWork() other than that the semantics of the calls and when you use a UnitOfWork is still dependant on the requirements of your application. For instance I noticed that originally the findSomeObject method did not perform a transactional read (no UnitOfWork). Has the requirements for this method changed? If they have not then there is still no need to perform a transactional read, and the method would not need to change.
As for the requirement that new object be cached this is only required if you are not conforming the transactional queries and adds a slight performance boost for find by primary key queries. In order to use this however, objects must be assigned primary keys by the application before they are registered in the UnitOfWork.
--Gordon

Select One Choice attribute' LoV based on two bind variables, best practice

Hello there,
I am in the process of learning the ADF 11g, I have following requirement,
A page must contain a list of school names which is needed to be fetched based on two parameters, the parameters are student information been inserted in the previous page.
I have defined a read only view "SchoolNamesViewRO", it's query depends on two bind variables :stdDegree and stdCateg.
added that RO View as a view accessor to the entity to which the name attribute belongs, and then add LoV for the name attribute using the ReadOnly view,
added the name attribute as Select One Choice to page2,
and now I need to pass the values of the bind variables of the ReadOnly view,
the information needed to be passed as the bind variables is inserted in the previous page, I could have the data as bindings attribute values in the page2 definition
I have implemented the next two appraoches but both resulted in an empty list :
* added ExecuteWithParams Action to the bindings of the page and then defined an Invoke Action (set refresh condition) in the executable s, set the default values of the parameters to be the attributes values' input value,
in the trace I code see that the binding fetches correct values as supposed , but the select list appears empty, does the this execution for the query considered to be connected to the list ?
* added a method to the ReadOnly view Imp java class to set the bind variables, then I define it as a MethodAction in the bindings , and then create an Invoke action for it , also the select is empty,
if the query been executed with the passed variables, then why the list is empty? is it reading data from another place than the page!
and what is the best practice to implement that requirement?
would the solution be : by setting the default value of the bind variables to be some kind of Expression!
please notice that query execution had the bound variables ( I see in the trace) are set to the correct values.
would you give some hints or redirect me to a useful link,
Thanks in advance
Regards,

please give me any example using backing bean .for example
<?xml version='1.0' encoding='UTF-8'?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="2.1"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:af="http://xmlns.oracle.com/adf/faces/rich">
<jsp:directive.page contentType="text/html;charset=UTF-8"/>
<f:view>
<af:document id="d1">
<af:form id="f1">
<af:selectOneChoice label="Label 1" id="soc1" binding="#{Af.l1}"
autoSubmit="true">
<af:selectItem label="A" value="1" id="si1"/>
<af:selectItem label="B" value="2" id="si2"/>
</af:selectOneChoice>
<af:selectOneChoice label="Label 2" id="soc2" disabled="#{Af.l1=='2'}"
partialTriggers="soc1">
<af:selectItem label="C" value="3" id="si3"/>
<af:selectItem label="D" value="4" id="si4"/>
</af:selectOneChoice>
</af:form>
</af:document>
</f:view>
</jsp:root>
package a;
import oracle.adf.view.rich.component.rich.input.RichSelectOneChoice;
public class A {
private RichSelectOneChoice l1;
public A() {
public void setL1(RichSelectOneChoice l1) {
this.l1 = l1;
public RichSelectOneChoice getL1() {
return l1;
is there any mistake

Best Practice for EJB calls from servlet?

Hi folks
I could not find general rules for making calls to an stateful EJB from the web container (e.g. from a backingBean). In some books they say it is a bad programming style calling them directly from a common servlet. The book says create first an HTTPSession Object and from there call the stateful EJB.
I'm a bit confused because, I'm missing some best practice guide from where to initiate such calls.
Can somebody please point me in the right direction?
Kind Regards
Bruno
Edited by: zajoho on Oct 30, 2008 11:14 PM

Hi Bruno,
The main issue with the combination of stateful session beans and servlets is the servlet threading model.
It is dangerous to store a stateful session bean reference in servlet instance state, since the servlet instance
can be accessed concurrently, yet a stateful session bean reference is intended to be used by only one
client.
As you point out, one alternative is to store the reference in the HttpSession. That associates the reference
with a particular client, which matches the stateful session bean programming model.

Best practice for customizing EJB property after deployment

Hi Gurus,
What is the best practice for customizing EJB property after deployment in NW7.1? I have a stateless session bean and it needs to get some environment information before acting. While the information can only be known at runtime. What should I do to achieve it? I thought I can bind the property with a JNDI context but I did not find out where to declare and change the context value. Please advise. Thanks.
B.R.

Hi.
I have a similar problem. But I still can not edit the properties of the ejb-jar.xml.
I tried to stop the web service, but the properties still remain unmodifiable.
Could you advise me how to change them?
We have installed SAP Server 7.0.2

BPC:NW - Best practices to load Transaction data from ECC to BW

I have a very basic question for loading GL transaction data into BPC for variety of purposes, would be great if you can point me towards best practices/standard ways of making such interfaces.
1. For Planning
When we are doing the planning for cost center expenses and need to make variance reports against the budgets, what would be the source Infocube/DSO for loading the data from ECC via BW, if the application is -
YTD entry mode:
Periodic entry mode:
What difference it makes to use 0FI_GL_12 data source or using 0FIGL_C10 cube or 0FLGL_O14 or 0FIGL_D40 DSOs.
Based on the data entry mode of planning application, what is the best way to make use of 0balance or debit_credit key figures on the BI side.
2. For consolidation:
Since we need to have trading partner, what are the best practices for loading the actual data from ECC.
What are the typical mappings to be maintained for movement type with flow dimensions.
I have seen multiple threads with different responses but I am looking for the best practices and what scenarios you are using to load such transactions from OLTP system. I will really appreciate if you can provide some functional insight in such scenarios.
Thanks in advance.
-SM

For - planning , please take a look at SAP Extended Financial Planning rapid-deployment solution: G/L Financial Planning module. This RDS captures best practice integration from BPC 10 NW to SAP G/L. This RDS (including content and documentation) is free to licensed customers of SAP BPC. This RDS leverages the 0FIGL_C10 cube mentioned above.
https://service.sap.com/public/rds-epm-planning
For consolidation, please take a look at SAP Financial Close & Disclosure Management rapid-deployment solution. This RDS captures best practice integration from BPC 10 NW to SAP G/L. This RDS (including content and documentation) is also free to licensed customers of SAP BPC.
https://service.sap.com/public/rds-epm-fcdm
Note: You will require an SAP ServiceMarketplace ID (S-ID) to download the underlying SAP RDS content and documentation.
The documentation of RDS will discuss the how/why of best practice integration. You can also contact me direct at [email protected] for consultation.
We are also in the process of rolling out the updated 2015 free training on these two RDS. Please register at this link and you will be sent an invite.
https://www.surveymonkey.com/s/878J92K
If the link is inactive at some point after this post, please contact [email protected]

Can i call Bean managed EJB with transaction attribute Required New

          I am calling a BeanManaged EJB which has a transaction attribute
          set to Required New from a container managed bean. Does it create a new transaction
          other than the Bean managed transaction. Do i really need a required new field
          transaction attribute.All i need is user controlled transaction.Do i need to set
          the transaction aatibute.
          Thanks
          Krish.


Hi Krish,
          The question does not make much sense.
          I would suggest that you set all your tx settings to "Required" unless you
          have a specific reason to do otherwise, and in those few instances that you
          have a specific reason to do otherwise, then change it in just those places.
          Peace,
          Cameron Purdy
          Tangosol Inc.
          << Tangosol Server: How Weblogic applications are customized >>
          << Download now from http://www.tangosol.com/download.jsp >>
          "KRISH" <[email protected]> wrote in message
          news:[email protected]..
          >
          > I am calling a BeanManaged EJB which has a transaction attribute
          > set to Required New from a container managed bean. Does it create a new
          transaction
          > other than the Bean managed transaction. Do i really need a required new
          field
          > transaction attribute.All i need is user controlled transaction.Do i need
          to set
          > the transaction aatibute.
          >
          > Thanks
          >
          > Krish.
          >

Assignment of transaction attributes in ejb-jar.xml

Hi all,
I'm going through the employee example from the book "Java programming in SAP web application server". I have followed the instrucstions to the letter and have triple checked that i did not miss anything.
During the part "Defining Transaction Control", when i go to the "Assembly" tab, choose "Container-transaction" and click add; i get the following error message.
You have to create and reference EJBs first. Afterwards you can choose them here.
Newly created EJBs are referenced automatically in the ejb-jar.xml, in special cases you might have to reference them manually.
Below is a copy of the ejb-jar. Both beans are referenced in the file so i don't really understand the error message!
Thanks for your help.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">
<ejb-jar>
     <description>EJB JAR description</description>
     <display-name>EJB JAR</display-name>
     <enterprise-beans>
          <session>
               <ejb-name>EmployeeServicesBean</ejb-name>
               <home>com.sap.demo.EmployeeServicesHome</home>
               <remote>com.sap.demo.EmployeeServices</remote>
               <local-home>com.sap.demo.EmployeeServicesLocalHome</local-home>
               <local>com.sap.demo.EmployeeServicesLocal</local>
               <ejb-class>com.sap.demo.EmployeeServicesBean</ejb-class>
               <session-type>Stateless</session-type>
               <transaction-type>Container</transaction-type>
               <ejb-local-ref>
                    <ejb-ref-name>ejb/Employee</ejb-ref-name>
                    <ejb-ref-type>Entity</ejb-ref-type>
                    <local-home>com.sap.demo.EmployeeLocalHome</local-home>
                    <local>com.sap.demo.EmployeeLocal</local>
                    <ejb-link>EmployeeEjb.jar#EmployeeBean</ejb-link>
               </ejb-local-ref>
          </session>
          <entity>
               <ejb-name>EmployeeBean</ejb-name>
               <home>com.sap.demo.EmployeeHome</home>
               <remote>com.sap.demo.Employee</remote>
               <local-home>com.sap.demo.EmployeeLocalHome</local-home>
               <local>com.sap.demo.EmployeeLocal</local>
               <ejb-class>com.sap.demo.EmployeeBean</ejb-class>
               <persistence-type>Container</persistence-type>
               <prim-key-class>java.lang.Long</prim-key-class>
               <reentrant>False</reentrant>
               <cmp-version>2.x</cmp-version>
               <abstract-schema-name>EmployeeBean</abstract-schema-name>
               <cmp-field>
                    <field-name>lastname</field-name>
               </cmp-field>
               <cmp-field>
                    <field-name>firstname</field-name>
               </cmp-field>
               <cmp-field>
                    <field-name>id</field-name>
               </cmp-field>
               <cmp-field>
                    <field-name>department</field-name>
               </cmp-field>
               <primkey-field>id</primkey-field>
               <query>
                    <description>Query for getting all employee objects.</description>
                    <query-method>
                         <method-name>findAllEmployees</method-name>
                         <method-params/>
                    </query-method>
                    <ejb-ql>Select object (p) from EmployeeBean p</ejb-ql>
               </query>
          </entity>
     </enterprise-beans>
     <assembly-descriptor/>
</ejb-jar>

I was able to add the transaction attributes manually to the ejb-jar.xml file. below is what the file looks like now for those interested.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">
<ejb-jar>
     <description>EJB JAR description</description>
     <display-name>EJB JAR</display-name>
     <enterprise-beans>
          <session>
               <ejb-name>EmployeeServicesBean</ejb-name>
               <home>com.sap.demo.EmployeeServicesHome</home>
               <remote>com.sap.demo.EmployeeServices</remote>
               <local-home>com.sap.demo.EmployeeServicesLocalHome</local-home>
               <local>com.sap.demo.EmployeeServicesLocal</local>
               <ejb-class>com.sap.demo.EmployeeServicesBean</ejb-class>
               <session-type>Stateless</session-type>
               <transaction-type>Container</transaction-type>
               <ejb-local-ref>
                    <ejb-ref-name>ejb/Employee</ejb-ref-name>
                    <ejb-ref-type>Entity</ejb-ref-type>
                    <local-home>com.sap.demo.EmployeeLocalHome</local-home>
                    <local>com.sap.demo.EmployeeLocal</local>
                    <ejb-link>EmployeeEjb.jar#EmployeeBean</ejb-link>
               </ejb-local-ref>
          </session>
          <entity>
               <ejb-name>EmployeeBean</ejb-name>
               <home>com.sap.demo.EmployeeHome</home>
               <remote>com.sap.demo.Employee</remote>
               <local-home>com.sap.demo.EmployeeLocalHome</local-home>
               <local>com.sap.demo.EmployeeLocal</local>
               <ejb-class>com.sap.demo.EmployeeBean</ejb-class>
               <persistence-type>Container</persistence-type>
               <prim-key-class>java.lang.Long</prim-key-class>
               <reentrant>False</reentrant>
               <cmp-version>2.x</cmp-version>
               <abstract-schema-name>EmployeeBean</abstract-schema-name>
               <cmp-field>
                    <description>
                    </description>
                    <field-name>lastname</field-name>
               </cmp-field>
               <cmp-field>
                    <description>
                    </description>
                    <field-name>firstname</field-name>
               </cmp-field>
               <cmp-field>
                    <description>
                    </description>
                    <field-name>id</field-name>
               </cmp-field>
               <cmp-field>
                    <description>
                    </description>
                    <field-name>department</field-name>
               </cmp-field>
               <primkey-field>id</primkey-field>
               <query>
                    <description>Query to get all employee objects.</description>
                    <query-method>
                         <method-name>findAllEmployees</method-name>
                         <method-params/>
                    </query-method>
                    <ejb-ql>Select object (p) from EmployeeBean p</ejb-ql>
               </query>
          </entity>
     </enterprise-beans>
     <assembly-descriptor>
          <container-transaction>
               <description>container-transaction</description>
               <method>
                    <ejb-name>EmployeeBean</ejb-name>
                    <method-name>*</method-name>
               </method>
               <method>
                    <ejb-name>EmployeeServicesBean</ejb-name>
                    <method-name>*</method-name>
               </method>
               <trans-attribute>Required</trans-attribute>
          </container-transaction>
     </assembly-descriptor>
</ejb-jar>
Thanks

Best Practice EJB 3.0 Question

I have a web application consisting of 3 projects:
- Model (EJB 3.0 Session Beans connected to two different databases)
- TagLibrary (custom tag library)
- ViewController (Web App / GUI)
Currently I am connecting to the EJB Beans using code that Jdeveloper generates for a test client:
env.put( Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory" );
env.put(Context.PROVIDER_URL, "t3://localhost:7101");
However would like to move these to a properties file (I believe jndi.properties) such that they can be modified based on app server.
My question is following:
What is best practice for Session beans in the Model project to access other session beans in the same project? Do I also need to specify JNDI prop file and settings? (This occurs when Bean from one database needs to access bean from another database).
Or should I really put these in two separate projects / EJB libraries?
Thanks,
Kris

You have two options, first is to use JNDI lookup (you should be able to use just new InitialContext(), without the environment map).
Second one is more elegant and, as far as I'm concerned, should be referred to as best practice, that is using dependency injection:
@EJB
YourSesionBeanInterface yourEJB;
If you get stuck, there is plenty of documentation about this on the internet.
Pedja

Oracle Best Practices for generating Transactions IDs in high OLTP systems

We are in the process of designing a high OLTP system using Oracle 11g Database with the following NFRs:
1) 1 million transactions per day
2) 100,000 concurrent users
There are close to about 160-180 entities in the database and we want to know the best approach/practice in deriving the transaction IDs for the OLTP system. Our preferences are given below:
1) Use Oracle Sequence starting with 1,000,000,000 (1 billion) - This is to make the TXN ID look meaningful when it starts with 1 billion instead of starting it with 1.
2) Use timestamp and cast it to number instead of using Oracle sequence.
Note: Transaction IDs must appear in sequence as they are inserted - be it sequence/timestamp
I would like to know pros/cons of the above methods and their impacts on performance. Also, appreciate if you could share any any best practices/methods that Oracle supports.
Thanks in advance.
Ken R

Ken R wrote:
I did a quick PoC using both Oracle Sequence & Timestamp for 1 million inserts in a Non-RAC environment. Code used is given below:
create sequence testseq start with 1 cache 10000 order;
create table test1 (txnid number, txndate timestamp(9));
create table test2 (txnid number, txndate timestamp(9));
begin
for i in 1..1000000
loop
insert into test1 values(testseq.nextval,systimestamp(9));
end loop;
commit;
end;
begin
for i in 1..1000000
loop
insert into test2 values(to_number(to_char(systimestamp(9),'yyyymmddhh24missff9')), systimestamp(9));
end loop;
commit;
end;
Here are the results:
select max(txndate)-min(txndate) from test1;
Result >> 0 0:3:3.514891000
select max(txndate)-min(txndate) from test2;
Result >> 0 0:1:32.386923000
It appears that Timestamp is faster than sequence... Any thought is highly appreciated...Interesting that your sequence timing is so slow. You say this was a non-RAC environment, but I wonder if you had Oracle linked in RAC mode even though you were running single instance - this would result in the ORDERed sequence running through RAC's "DFS Lock Handle" mechanism which might account for the timing anomaly.
Unfortunately your test is not particularly relevant. As DomBrooks points out there are lots of problems with sequence-based or time-based columns, especially in RAC, and most particularly if you think you want a "no-gap" sequence. On top of this, of course, your test doesn't include an index on the relevant column, and it's single user and doesn't test for any concurrency effects.
Typical performance problems are: your RAC instances spend all their time negotiating who gets to use the next value; the index you use to enforce uniqueness suffers from massive contention on the "high-value" block unless you create a reverse-key index - at which point you have to be able to cache the entire index to minimise I/O overheads; you can hash partition the index to avoid using the reverse-key option - but that costs a lot of money if you don't already license the partitioning option.
Regards
Jonathan Lewis

EJB + "transaction attributes" + "best practice"

Similar Messages

Maybe you are looking for