Generating non-sequential primary keys

Is there a simple way to generate non-sequential primary keys? Say for instance I want to generate a user ID. I'd like all of the IDs to be unique, but not strictly sequential.

>
Hi Crottyan,
Is there a simple way to generate non-sequential primary keys? Say
for instance I want to generate a user ID. I'd like all of the IDs to be
unique, but not strictly sequential.Normally this is done to eliminate contentation for index inserts - why do
you want to do it?
Be careful with GUID - it can be [url http://en.wikipedia.org/wiki/Globally_unique_identifier#Sequential_algorithms]sequential.
It's a pity you didn't tell us your version of Oracle :( - you should always do this.
10 XE has a sequential algorithm. 11 XE doesn't.
HTH,
[Edit] Just saw your post about inferring insert order - fair enough. Will be able to tell you about 11 EE next
week ;)
Paul...
Edited by: Paulie on 18-Jul-2012 18:03

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How to insert a sequence as a primary key

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Hi Katy,
I'm about to post a HOWTO on this subject.
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Problem with JPA Implementations and SQL BIGINT in primary keys

I have a general Question about the mapping of the SQL datatype BIGINT. I discovered, that there are some different behaviour depending on the JPA implementation. I tested with TopLink Essentials (working) and with Hibernate (not working).
Here is the case:
Table definition:
/*==============================================================*/
/* Table: CmdQueueIn */
/*==============================================================*/
create table MTRACKER.CmdQueueIn
CmdQueueInId bigint not null global autoincrement,
Type int,
Cmd varchar(2048),
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MLUser bigint not null,
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The java class for this table has the following annotation for the primary key field:
@Id
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@Column(name = "CmdQueueInId", nullable = false)
private BigInteger cmdQueueInId;
When using hibernate 3.2.1 as JPA provider I get the following exception:
avax.persistence.PersistenceException: org.hibernate.id.IdentifierGenerationException: this id generator generates long, integer, short or string
at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:629)
at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:218)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
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at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:176)
at $Proxy16.persist(Unknown Source)
at com.trixpert.dao.CmdQueueInDAO.save(CmdQueueInDAO.java:46)
at com.trixpert.test.dao.CmdQueueInDAOTest.testCreateNewCmd(CmdQueueInDAOTest.java:50)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at
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at org.hibernate.id.IdentityGenerator$BasicDelegate.getResult(IdentityGenerator.java:157)
at org.hibernate.id.insert.AbstractSelectingDelegate.performInsert(AbstractSelectingDelegate.java:57)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2108)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2588)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:48)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:290)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:180)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:108)
at org.hibernate.event.def.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:131)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:87)
at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:38)
at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:618)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:592)
at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:596)
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This means, that their ID generator does not support java.math.BigInteger as datatype.
But the code works if I take TopLink essentials as JPA Provider.
Looking at the spec shows the following:
In chapter 2.1.4 "If generated primary keys are used, only integral types will be portable." Integral datatypes are byte, short, int, long and char. This would mean, that the Hibernate implementation fits the spec but there seem to be a problem in general with BIGINT datatypes.
I use a SYBASE database. There it is possible to declare a UNSIGNED BIGINT. The range of numbers is therefore 0 - 2^64 - 1. Since in Java a long is always signed it would mean its range is from -2^63 -1 to 2^63 -1. So a mapping of BIGINT to java.lang.long could result in an overflow.
The interesting thing is, that I used NetBeans to reverse engineer an existing database schema. It generated for all Primary Keys of Type BIGINT automatically a java.math.BigInteger. But for other fields (not being keys) it mapped BIGINTs to java.lang.long.
It looks like there are some problems with either the spec itself or the implementation of it. While TopLink seems to handle the problem correctly, Hibernate doesn't. But Hibernate seems to fulfill the spec.
Is anybody familiar with the Spec reading this and can elaborate a little about this situation?
Many thanks for your input and feedback.
Tom

Not sure if I clearly understand your issue, would be good if you can explain it a bit more clearly.
"I select a value from LOV and this value don't refresh in the view"
If you mean ViewObject, check if autoSubmit property is set to true.
Amit

Using table with no primary key

I habe some older table that use unique indexes (instead of primary keys). Some of these are comprised of 3 or 4 columns (see below). When I try to create an HTML DB tabular form or report is it asking for primary key. How do I get around this?
CREATE UNIQUE INDEX COURSES ON COURSE(START_YY,SCHOOL,CLASS_CD)
TABLESPACE starindx
STORAGE (INITIAL 61440
NEXT 61440
PCTINCREASE 0);

You will have to code your own inserts, updates, and deletes along with optimist row locking, which is painful.
To use HTML DB's built-in/default inserts, deletes, updates, and optimistic row locking, add a number column to your table. Make that new column be the primary key on the table. In the HTML PAGE populate it from a number generator. The primary key column will in essence function like a rowid for the row. The only thing you will want to do is code a validation to check for a unique combination of START_YY,SCHOOL, and CLASS_CD in the table so the page can present a more pleasing 'duplicate key on index' message in the event that the user has matched an already existing tuple.

Autonumber for Primary Key in Z Table

Hi,
I want to use an auto generated number as primary key for a Z table that i want to create. Is there some exiting data element tht I can use, so that I dont have to explicitly enter the primary key everytime i enter a record in SM30

Hi,
There is no automatically way of generating number...
But You can create a number range object in the transaction SNRO.
Then use the FM NUMBER_GET_NEXT to get the next number....
Then assign that number using the event 05 "new entries" which you can set in the view TVIMF.
Thanks,
Naren

Problem in generating the Primary Key

Hi All ,
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import java.util.HashMap;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
import javax.persistence.PersistenceUnit;
public class entityCaller {
//     @PersistenceContext(unitName="testApp" ,type=PersistenceContextType.EXTENDED)
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//     @PersistenceUnit(unitName="testApp")
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My persistence.xml looks like this :
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.0" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="testApp">
<provider>oracle.toplink.essentials.ejb.cmp3.EntityManagerFactoryProvider</provider>
<class>Tab1</class>

<properties>

<property name="toplink.jdbc.driver" value="oracle.jdbc.driver.OracleDriver"/>
<property name="toplink.jdbc.url" value="jdbc:oracle:thin:@127.0.0.1:1521:XE"/>
<property name="toplink.jdbc.user" value="system"/>
<property name="toplink.jdbc.password" value="jlkklkj"/>


</properties>
</persistence-unit>
</persistence>
Please provide me with some pointer as to know where the things are going wrong.

If you generated your original schema using toplink.ddl-generation, then later dropped it and created it then you should keep in mind the sequence table does not get dropped. This can lead to an initially 'empty' database with a PK sequence starting at '2' if you have one persistence unit and one entity. Can you steadily duplicate this or did you just notice that your persist started with an key of '2'? Just a thought.

Can I have a primary key as a non-unique column

Hi all,
I have a table with 35 columns and only one column in a not null column. But this column data is not unique. I want to create a primary key with non-unique index, can I don it, if it is not possible is there any other way to it. Please help me with this.
Thanks for your help.vinaykotha

1) Do the 'Unique Column combination' check first, using this example. (Pl. Change the column name and number of columns you consider as candidate key.) The SQL as follows:-
;WITH CTE (ProductKey, CustomerKey, SalesTerritoryKey, DupRec)
AS
(SELECT ProductKey, CustomerKey, SalesTerritoryKey, ROW_NUMBER() OVER
(PARTITION BY ProductKey, CustomerKey, SalesTerritoryKey
ORDER BY ProductKey, CustomerKey, SalesTerritoryKey) AS DupRec
FROM dbo.FactSales
SELECT *
FROM CTE
WHERE DupRec > 1
2) if CTE Table returns no records, you are good to create a Composite CLUSTERED PRIMARY KEY, like:
ALTER TABLE dbo.FactSales
ADD CONSTRAINT PK_ProductKey_CustomerKey_SalesTerritoryKey
PRIMARY KEY CLUSTERED (ProductKey, CustomerKey, SalesTerritoryKey);
If no error..bingo! if NOT, Don't worry, create a Composite Index like this:-
3)
CREATE NONCLUSTERED INDEX [IX_ProductKey_CustomerKey_SalesTerritoryKey]
ON dbo.FactSales(ProductKey, CustomerKey, SalesTerritoryKey);
This will work still efficiently. Usually all transaction table are like that like Daily_Order table, Ship_Details table etc.
-NC

Entity bean with another class as primary key generator class

Hi All,
I have a CMP entity bean in which I generate the primary key using my own class know as unique id generator.
I use it in ejbCreate method in the following manner
public Long ejbCreate(HospitalData hospitalData) throws CreateException{
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Can you tell me how I map this primary key in my ejb-jar.xml and jbosscmp-jdbc.xml.
Anyhelp would be appreciated.
Thanks
Sameer

"Bhamu" <[email protected]> wrote in message
news:9keuo4$[email protected]..
I am trying to develop an entity bean attached to a key which have a
composite key using Primary Key Class. When I use the findByPrimaryKey
method of the bean it throws an exception as follows,I notice that you are using the reference CMP plugin.
at com.netscape.server.ejb.SQLPersistenceManager.find(Unknown Source)I'm also willing to bet that you may have created your own primary key class
with a single field, rather than using the fields type as a primitive
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It is badly written, and has some stupid assumptions. The one I remember
the most is that if you only have one primary key field, then
SQLPersistenceManager assumes you have used a primitive type such as
java.lang.String or java.lang.Integer, to represent it, rather than creating
your own <Enity>Pk.java file.
SQLPersistenceManager works for toy examples, but in general I would say it
is broken and unusable. Either use BMP, or splash out the money for Coco
Base from Thought Inc. Currently the only CMP plugin for iPlanet App server,
other than the reference implementation, that I know of.

Entity bean with primary key generated by trigger

Hi,
We have a table(oracle) with one column as primary key,
but the primary key is generated by trigger every time
a new row is inserted into this table, inside the trigger,
it uses oracle sequence to get the next val.
If we want to use entity bean with it, what should we specify, it's not application-managed primay key, it's
not auto-generated primary key either. How can we resolve
it without change the database part.
Any thought is appreciated.
Thanks
afang

The code is already there with JDBC call inserting
into the table, the inserting trigger then will generate
sequence key and being inserted into primary key column.
Now wondering if it's possible to change the code to use entity bean but without modifying the trigger (since it contains other business logics).

Help required to generate primary key sequence

Hello All,
I need your help in generating a sequence for primary key in my db table created using java dictionary project in my NWDS 7.3.
The table column EMPL_ID is a primary and needs to be a sequence. The code in the JPA entity is as below. The underlying database is DB2 on Linux. Kindly help me resolve this issue.
* The persistent class for the TMP_EMPL_DATA database table.
@Entity
@Table(name="TMP_EMPL_DATA")
public class TmpEmplData implements Serializable {
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     @Column(name="EMPL_ID")
     private String _emplId_;
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Caused by: javax.persistence.PersistenceException: The generated SQL statement is not valid for the underlying database platform (platform no. 99). For more details see attached exception. SQL statement is SELECT NEXT VALUE FOR "EMPID_SEQ" FROM ( VALUES (1) )
at com.sap.engine.services.orpersistence.sqlmapper.mapping.JPASQLMapperImpl.createSequenceIDGeneratorSelectText(JPASQLMapperImpl.java:1239)
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at com.sap.engine.services.orpersistence.entitymanager.EntityManagerFactoryImpl.<init>(EntityManagerFactoryImpl.java:137)
at com.sap.engine.services.orpersistence.entitymanager.JtaEntityManagerFactoryImpl.<init>(JtaEntityManagerFactoryImpl.java:39)
at com.sap.engine.services.orpersistence.provider.PersistenceProviderImpl.createJtaEntityManagerFactory(PersistenceProviderImpl.java:251)
at com.sap.engine.services.orpersistence.provider.PersistenceProviderImpl.createContainerEntityManagerFactory(PersistenceProviderImpl.java:236)
at com.sap.engine.services.orpersistence.container.EMFInstanceCreator.getEntityManagerFactory(EMFInstanceCreator.java:134)
at com.sap.engine.services.orpersistence.container.ORPersistenceObjectFactory.getEMF(ORPersistenceObjectFactory.java:300)
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... 134 more
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at com.sap.sql.tree.impl.OpenSqlTextExpert.nextValueExpressionToText(OpenSqlTextExpert.java:185)
at com.sap.sql.tree.impl.NextValueExpressionBuilderImpl$NextValueExpressionImpl.toSqlTxt(NextValueExpressionBuilderImpl.java:140)
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Hi,
does the sequence exist? SAP JPA does not support creation of sequences, you have to create it manually.
Maybe SAP JPA also does not support DB2 sequences with "Open SQL" correctly.
- Tryp to set your data source to "native" or "vendor".
- Try to turn on oracle compatibility:
db2set DB2_COMPATIBILITY_VECTOR=ORA
Regards
Rolf

Primary Key - Generated by database TRIGGER

Hi,
I have a form with a block that is attached to a table. So far, nothing fancy :-)
The Primary is generated with an ORACLE SEQUENCE. That is done at the TABLE level with a DATABASE trigger.
So in the form, the primary field is not populated.
Works fine. But if the user wants to UPDATE the forms content, right after they did an INITIAL commit, THEY CAN'T !!!!!!!!!!!
How can I code this in the form?
Is there a way to syncronize (populate) the primary key in the form with it's table content?
If so, how do I query the table if I don't have the primary key value ?
Thanks for ANY advise,
Marc.

Another solution is to use both a database trigger and a PRE-INSERT trigger in Forms.
The database trigger should be something like
CREATE TRIGGER INS_TABLENAME BEFORE INSERT ON TABLENAME
FOR EACH ROW WHEN (new.ID IS NULL)
BEGIN
SELECT TABLENAME_SEQ.nextval INTO :new.ID FROM DUAL;
END;
and the PRE-INSERT trigger should be something like:
SELECT TABLENAME_SEQ.nextval INTO :blockname.ID FROM DUAL;
This way one solves the problem of DML RETURNING VALUE not working in Forms with Oracle version > 8 (does it work on version 8 as it is said to be? - i have not tested it anyway) and the use of other applications (SQL*Plus, JAVA, etc) without writing any code.

Sequences to generate primary keys

Hi,
A question on using sequences to generate primary keys. We have a table and in all environments, test, uat, prod, a sequence exists to generate the primary key for the table. This table is a reference table and is not updateable by the users.
When developing scripts to insert records into the table, the developers are currently not using the sequence but typing in unique numbers so data scripts consist of something like this:
INSERT INTO EMPLOYEE_GROUP
(employee_group_id, code, description,...)
VALUES
(45,'sdf','sdfsdfsf');
INSERT INTO EMPLOYEE_GROUP
(employee_group_id, code, description,...)
VALUES
(46,'sdf','sdfsdfsf',...);
a) Is this normal practice?
b) Sometimes they are using the sequence to generate the primary key in development but then hardcoding the number in the script so in development the sequence might be at 160, but in the other environments the sequences will still be at one. Is this also normal practice?
My usual method in developing scripts is to use <seqeunce>.nextval but it's somewhat incompatitble in the current environment.

You are using a surrogate, or synthetic primary key. For a primary key generated in this way, the value is inconsequential. All that matters is that it is unique and the tables with foreign keys into it, if any, also have that value set properly. But it doesn't matter if the value is 1, 100, 12344, 2222222222, etc. All you care about is the uniqueness.
If you create the data properly then child records and their parents should be correct in all systems you mention, it's just that the actual value of the key will differ and that's fine. You care about the relationship of the records, not the value of the synthetic keys.

Primary Key - non sequenced - can this cause problems??

We are seeing some strange explain plans for some queries in our 10.2.0.3 database. It just seems to me that Oracle is not using the index(es) that we expect it to use. In our discussions it was brought up that the data in the Primary Key fields in our tables are not sequential at all. I am wondering if this can be causing some issues with Oracle and it's explain plans.
Can the fact that our PK fields are not sequential be causing some issues with Oracle and the optimizer?

Things to consider:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/ex_plan.htm#sthref1858
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/optimops.htm#sthref1254
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/optimops.htm#i82005
Message was edited by:
dbtoo
system stats - http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/stats.htm#i41496

Primary Key supported by a non-unique index?

Encountered a weird situation today. A utility we setup which allows Analysts to restore data into their tables, started failing when it attempted to drop an index. The index was supporting a Primary Key. Makes sense. But our script was supposed to only be attempting to drop/recreate non-unique indexes. Turns out the supporting index on the Primary Key was non-unique, and to the best of my knowledge came about as follows:
SQL> create table junk (f number(1));
Table created.
SQL> create index junk_ix on junk(f);
Index created.
SQL> select UNIQUENESS from DBA_INDEXES where index_name = 'JUNK_IX';
UNIQUENES
NONUNIQUE
SQL> alter table forbesc.junk add constraint junk_pk primary key (f) using index junk_ix;
Table altered.
SQL> select UNIQUENESS from DBA_INDEXES where index_name = 'JUNK_IX';
UNIQUENES
NONUNIQUE
SQL> insert into junk values (1);
1 row created.
SQL> insert into junk values (1);
insert into junk values (1)
ERROR at line 1:
ORA-00001: unique constraint (FORBESC.JUNK_PK) violated
SQL> select index_name from dba_constraints where constraint_name = 'JUNK_PK';
INDEX_NAME
JUNK_IXWhat I can't figure out is how a non-unique index is enforcing uniqueness. I thought that it was the key in that very same process. I thought that perhaps an index with the 'SYS_123456' was getting created, perhaps, but I couldn't find one:
SQL> select object_name, object_type from dba_objects order by created desc;
OBJECT_NAME   OBJECT_TYPE
JUNK_IX     INDEX
JUNK     TABLE
...How is the uniqueness getting enforced in this case? This is in Oracle 11.1.0.7
Thanks,
--=Chuck

It has always been that way. Oracle can, and will, use a non-unique index to enforce a PK constraint, The existing index just needs to have the PK column(s) as the leading column(s) of the index:
SQL> create table t (id number, id1 number, descr varchar2(10));
Table created.
SQL> create index t_ids on t(id, id1);
Index created.
SQL> select index_name from user_indexes
2 where table_name = 'T';
INDEX_NAME
T_IDS
SQL> alter table t add constraint t_pk
2 primary key (id);
Table altered.
SQL> select index_name from user_indexes
2 where table_name = 'T';
INDEX_NAME
T_IDS
SQL> insert into t values (1, 1, 'One');
1 row created.
SQL> insert into t values (1, 2, 'Two');
insert into t values (1, 2, 'Two')
ERROR at line 1:
ORA-00001: unique constraint (OPS$ORACLE.T_PK) violatedJohn

If I have an EntityBean that mappes to two tables within one database, when I create that EJB, whoes reponsibilty to generate the primary key in database table? The RDBMS or EJB?

If I have an EntityBean that mappes to two tables within one database, when I create
that EJB, whoes reponsibilty to generate the primary key in database table? The
RDBMS or EJB?
Thanks,
JW

Refer to http://e-docs.bea.com/wls/docs81/faq/ejb.html/#257430
"Jingwei Zhang" <[email protected]> wrote:
>
If I have an EntityBean that mappes to two tables within one database,
when I create
that EJB, whoes reponsibilty to generate the primary key in database
table? The
RDBMS or EJB?
Thanks,
JW

Generating non-sequential primary keys

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