Using sequence in a multiuser environment

We plan to use table wise sequences to generate incremental ID's for each Oracle table. Is this an issue in a multi user environment ? SOmebody said this could have contention issues and slow down performance. We expect this application to have in excess of 300 users on the LAN .
ANy inputs appreciated.

Hi!
This should not pose a big issue, if you have 300 users. Even if they modify a lot of tables - each table having their own sequence - the cache of the sequence will be refreshed when the last number is used. Choose a cache size for each sequence that will be refreshed for example once a day, and there shold not be a big performance problem.
cu
Andreas

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JDeveloper installation on WindowsXP Multiuser environment

Hello,
I've got a problem installing JDEveloper 10.1.3.3.0 on a WindowsXP multiuser environment.
I downloaded and extracted the archive into the C:\Programme directory (where it belongs) as admin user and I can start it without problems as long as I'm logged in as admin (despite the fact that a JDK 1.5 is already installed).
But when I try to start JDeveloper with a normal user account (without admin rights) from there I only get the splash screen progressing a little bit and nothing else happening afterwards.
So JDeveloper does not start for me within the account I want to use it with!
How can I manage to start JDeveloper for normal users on that WindowsXP system?
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It is recommended to unzip JDeveloper in a directory
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C:\Program Files, this one has a space in between. So
make sure you unzip into C:\oracle\jdeveloper or
something like that. Also make sure as admin grant
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execute.It is, I installed it into C:\Programme\JDeveloper.
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This is completely contradictory to the idea behind the restricted accounts in Windows!
Best Regards

Disadvantages of using sequence

Hi
Please let me know the disadvantages of using sequences.
Thank you

Massimo Ruocchio wrote:
I dislike that a sequence is called even if it doesn't need to be called:Why?
Because you lost numers?
There are many other scenarios in which you loose sequence's values, as I've already wrote, so if per your requirements you have not to loose values you simply cannot use a sequence, otherwise you can use it and there are no disadvantages...
Generally speaking I like or dislike many things: food, people, football (soccer) players, etc. But I cannot like or dislike a tool. I use it if it fits my needs otherwise I don't use it ;)
Max
[My Italian Oracle blog|http://oracleitalia.wordpress.com/2010/01/31/le-direttive-di-compilazione-pragma/]
I agree with michaels. It is a waste to generate sequence numbers when there is no need to generate them.
It's not because there are gaps, but because those gaps could be avoided.
Furthermore it could cause a performance problem, especially if the sequence is not cached or the cache is small and if you are in a RAC environment.
Of cause this issue can be circumvented with a different application logic. I myself use sequences mainly in triggers and avoid calling them directly.
However it would be nice if some smarter optimizer logic, would avoid fetching new sequence values, putting them in the buffer chache...ageing out other sequences because of that, etc.
"Dislike" is a good word for it. it's not a real problem/issue, but something that could have been implemented smarter, but wasn't.

MAX(SummaryNum) +1 bad idea, but how to use sequence part composite column

Hi,
My relational mode is as follows
Policy (policynum PK) has 1:M with Summary (policynum FK, SummaryNum part of PK, other columns part of PK)
Basically for each policy users can enter notes with SummaryNum 1, 2, 3, 4.... These numbers are shown to the user for tracking purpose. I need to make sure summary notes for EACH policy start with 1 (cannot really use sequence in the table in the strictest sense) and are incremented by 1. The current Oracle form basically creates the next highest possible value of SummaryNum by adding one to the currently available highest value. In brief, it is like a sequence number for summaries of a particular policy in the summary table.
PRE-INSERT
SELECT MAX(SummaryNum ) + 1
FROM Summary
I am trying to replicate this in ADF BC (using 11g) and know that not using sequencing and adding one to get the next number is a very bad idea due to concurrency challenges (transactional ACID properties). The reasons are as follows.
•     Using MAX(policy_memo_seq_num) + 1 is not scalable,
•     It will lead to duplicates in a multi-user environment, whether ADF BC, Oracle Forms, or any other technology
I also know how to use create a sequence in db, a related trigger, and then set the attribute in EO properties as DBSequence. My challenge is that since SummaryNum is not a primary key, and instead is part of a composite key in my case, how do I make sure that summary notes for EACH policy start with 1 in the Summary Table.
I appears that i cannot really use sequence in the table in the strictest sense as this will mean that for policies the summaryNum will start from the next available sequence number, but what i really want is to have it start by one for all policies.*
I would appreciate any help.
Thanks,

Not sure if there is a better way, but here is one way. Let's say your table was like this:
    SQL> desc versioned_item
     Name         Null?    Type
     ID           NOT NULL NUMBER
     VERSION      NOT NULL NUMBER
     DESCRIPTION           VARCHAR2(20)and lets say your data looked like this:
    SQL> select * from versioned_item order by id, version
            ID    VERSION DESCRIPTION
          1001          1 Item 1001
          1001          2 Item 1001
          1001          3 Item 1001
          1002          1 Item 1002
          1002          2 Item 1002
          1003          1 Item 1003To select only the rows for the max-version-id, you could do this:
    select id, version,description
    from versioned_item
    where (id,version) in (select id,max(version) from versioned_item group by id)
    order by id
            ID    VERSION DESCRIPTION
          1001          3 Item 1001
          1002          2 Item 1002
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About Document IDS in multiuser environment

I am developing an online application using oracle 8.0.5 , it is a multiuser environment , what is the best method to code about generating the number of documents from multiple places , how we can lock the number (document number e.g. Purchase Order) generated for one to another , please tell advice me the best & feasible approach to handle the tie of a mnumber from different sites and handeling of cancelation of any generated number from one person and alloting it to other users
thanks

Its bad because global variabels will be used and changed by different users at same time.
This will lead to variuos problem like user1 setting the variabel, user2 seting it , user1 using it with the value user2 set.

Using Berkeley With Two Different Environment Simultaneously

I am trying to use Berkeley with two different environment simultaneously in one program. But I am getting an error message of Databases left open. The first environment close with no error but the 2nd environment, having an error like this,
Exception in thread "main" java.lang.IllegalStateException: Unclosed Database: element_primary_key_index\\192.168.150.211\glassfish3\Berkeley\environment\Testing11
Unclosed Database: class_catalog\\192.168.150.211\glassfish3\Berkeley\environment\Testing11
Unclosed Database: element_database\\192.168.150.211\glassfish3\Berkeley\environment\Testing11
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     at com.svi.tools.gfs3v10domain.GFS3v10Domain.closeReadWrite(GFS3v10Domain.java:160)
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     at com.svi.tools.gfs3v10uploader.util.Uploader.uploadFiles(Uploader.java:89)
     at com.svi.tools.gfs3v10uploader.GFS3v10Uploader.mainMethod(GFS3v10Uploader.java:109)
     at com.svi.tools.gfs3v10uploader.GFS3v10Uploader.main(GFS3v10Uploader.java:52)
Please someone help me with my problem. Thanks in advance.

Hi Mark,
Here is my sample program for the problem:
import java.io.File;
import com.sleepycat.bind.serial.StoredClassCatalog;
import com.sleepycat.je.Database;
import com.sleepycat.je.DatabaseConfig;
import com.sleepycat.je.Environment;
import com.sleepycat.je.EnvironmentConfig;
import com.sleepycat.je.EnvironmentLockedException;
import com.sleepycat.je.SecondaryConfig;
import com.svi.tools.gfs3v10domain.objects.GFS3v10DomainElementData;
import com.svi.tools.gfs3v10domain.objects.GFS3v10DomainElementKey;
import com.svi.tools.gfs3v10domain.views.utils.ElementByPrimaryKeyCreator;
* Read Write Database used for every thing else.
public class MethodsSample implements GFS3v10Database {
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     private Environment environment = null;
     private boolean isClose = false;
     String environmentString;
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     private static StoredClassCatalog classCatalog;
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     private static Database elementByPrimaryKeyDatabase;
     private static Database catalogDatabase;
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     public MethodsSample() {
* Alternate Constructor.
* @param homeDirectory Location where the Database is Located.
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@Override
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environmentConfig.setTransactional(true);
environmentConfig.setAllowCreate(true);
environmentConfig.setDurability(DURABILITY);
while (environment == null) {
     try {
          environment = new Environment(new File(homeDirectory), environmentConfig);
     } catch(EnvironmentLockedException ele) {
          try {
                         Thread.sleep(500);
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@Override
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databaseConfig.setAllowCreate(true);
catalogDatabase = environment.openDatabase(null, CLASS_CATALOG + environmentString, databaseConfig);
classCatalog = new StoredClassCatalog(catalogDatabase);
elementDatabase = environment.openDatabase(null, ELEMENT_DATABASE + environmentString, databaseConfig);
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secondaryConfig.setDeferredWrite(true);
secondaryConfig.setAllowCreate(true);
secondaryConfig.setSortedDuplicates(true);
secondaryConfig.setKeyCreator(new ElementByPrimaryKeyCreator(classCatalog, GFS3v10DomainElementKey.class, GFS3v10DomainElementData.class, String.class));
elementByPrimaryKeyDatabase = environment.openSecondaryDatabase(null, ELEMENT_PRIMARY_KEY_INDEX + environmentString, elementDatabase, secondaryConfig);
@Override
     * Gets the Environment.
     * @return Environment.
public Environment getEnvironment() {
     return environment;
@Override
     * Gets the Class Catalog.
     * @return Class Catalog.
public StoredClassCatalog getClassCatalog() {
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@Override
     * Gets Element Database.
     * @return Element Database.
public Database getElementDatabase() {
     return elementDatabase;
@Override
     * Gets Element By Primary Key Database.
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public Database getElementByPrimaryKeyDatabase() {
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@Override
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     elementDatabase.close();
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     catalogDatabase.close();
     environment.close();
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public Boolean isClose() {
     return isClose;
     @Override
     public void closeOthers() {
for the Main:
public class sample {
     public static void main(String[] args) {
          String environment1 = "\\\\192.168.160.184\\glassfish\\berkeley\\environment\\home\\Multiple\\Testing11";
          String environment2 = "\\\\192.168.150.211\\glassfish3\\Berkeley\\environment\\Testing11";
          openCloseEnvironment(environment1, environment2);
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          MethodsSample forEnvironment1 = new MethodsSample(environment1); //Opens the Databases
          MethodsSample forEnvironment2 = new MethodsSample(environment2); //Opens the Databases
          forEnvironment1.closeUpload();
          forEnvironment2.closeUpload();
// same error happens no matter what sequence for closing
Thank you.

How to use Sequence in Forms

Hi,
I have an Empno Column, At the time of Opening a Form The Empno Will be displayed by using Sequence.
If the User doesn't save the Form Then the Empno Generated number will be changed.
How to write the code to get sequence numbers at Empno columns by using Sequence?
Thanks & Regards,
Hari Babu

Ok, I understand now your question. Since the oracle sequence is commited in a separate transaction, it is not possible to get the no-gap sequence, considering your example. In the other hand, if you don't commit immediately, than two concurrently opened forms could use the same sequence number, so you'll get the duplicate key!
If you're sure that this couldn't happen, you can manage your own sequencing, storing them in another table. Let's say you reached seq 999: entering the form, you'll read from your sequence table 1000, increment to 1001, and assign it to empno, but without commiting. Next time, you'll get the same number, until you commit form, and at the same time, change in seq table. So another will get 1001.
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Comenting code - style - how to keep coments where you want them - without using sequences

Silly question maybe about style of commenting.
Basically i like to use sequence boxes to keep comments on my diagram beside the bits of code that they refere to - otherwise when you use diagram cleanup (which i'm afraid i use all the time) they go anywhere. This is good - except that i found especially when doing FPGA programming the sequence boxes reduce the amount of parralelism that can go on - since the 'box' needs to finish before any of the outputs can be used. Is there some other method i should be using instead of sequence boxes to keep text beside elements - without enforcing that a set of elements are fixed in one place?
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Go to Solution.

I usually use labels of structures (loops, cases, etc) and labels of diagram constants, etc. for comments. In newer versions, we also have wire labels.
(see also)
What is your LabVIEW version? Also the LabVIEW 2011 cleanup does a better job keeping diagram comments together with the related code compared to earlier version.
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I am looking to develop Flex dashboard and use Flex in a Portal environment.
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Error Using Sequence in Weblogic

I tried to use Sequence object in weblogic to generate auto-imcremental integers
for my db insert keys. I first create a mydbsequece in oracle database. Then,
I built a class in which I obtain a dataSource using jndi to look for my dataSource.
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Qin Ding wrote:
>
I tried to use Sequence object in weblogic to generate auto-imcremental integers
for my db insert keys. I first create a mydbsequece in oracle database. Then,
I built a class in which I obtain a dataSource using jndi to look for my dataSource.
And then use the ds to getConnection. After I had the connection, I do the following:
Sequence sequence = new Sequence(con, "mydbsequence");
int i = sequence.nextValue();
When I call sequence.nextValue() method, I got the following error message: NullPointerException
at Weblogic.jdbc.rmi.SerialConnection.createStatement(SerialConnection.java:65).
Does anyone know what causes this error? and How do I fix it? Please advise me
on this. Thank you very much.
QinSequence is a non-standard JDBC object. It is an Oracle-specific class, which presumably
takes a standard java.sql.Connection in it's constructor. Oracle has repeatedly created
such new classes with methods claiming to take java.sql.* arguments, but in fact they
require an Oracle-specific class. In this case, however, we might succeed anyway if
we dig some. Can you show me the entire stacktrace of the exception?
Please take the attached jar file, and put it in front of all the weblogic stuff
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Using sequence in view

hi gurus
SQL> create view v1 as select s1.nextval from dual;
create view v1 as select s1.nextval from dual
*+
ERROR at line 1:
ORA-02287: sequence number not allowed here
Are there only workaround?
Thank you!

There are some restrictions on using sequences you will want to know about
http://download.oracle.com/docs/cd/B19306_01/server.102/b14231/views.htm#sthref3092

USING SEQUENCE IN PACKAGE SPEC

I Want to Use Sequence.NEXTVAL & Sequence.CURRVAL throughout the package. How can i declare the global sequence variable and make them available for all the stored procedures inside the package ?
Any help highly appreciated..
Thank you all in advance

Data Boy wrote:
No i know that but using directly SEQUENCE.CURRVAL inside the Insert statement is not a good practice.
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Sequence created.
SQL> ed
Wrote file afiedt.buf
1 create trigger trg_temp before insert on temp
2 for each row
3 begin
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5* end;
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7 /
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FULL_RES_NAME VARCHAR2(100 CHAR) NULL,
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ERR_MESS VARCHAR2(250 CHAR) NULL ,
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ORIGIN VARCHAR2(100 CHAR) NULL,
CONS_NAME VARCHAR2(35 CHAR) NULL,
CONS_TYPE VARCHAR2(2 CHAR) NULL,
ERR_COUNT NUMBER(10) NULL
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Using sequence in a multiuser environment

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