Bug in Oracle's handling of transaction isolation levels?

Question

Hello,
I think there is a bug in Oracle 9i database related to serializable transaction isolation level.
Here is the information about the server:
Operating System:     Microsoft Windows 2000 Server Version 5.0.2195 Service Pack 2 Build 2195
System type:          Single CPU x86 Family 6 Model 8 Stepping 10 GenuineIntel ~866 MHz
BIOS-Version:          Award Medallion BIOS v6.0
Locale:               German
Here is my information about the client computer:
Operaing system:     Microsoft Windows XP
System type:          IBM ThinkPad
Language for DB access: Java
Database information:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
The database has been set up using the default settings and nothing has been changed.
To reproduce the bug, follow these steps:
1. Create a user in 9i database called 'kaon' with password 'kaon'
2. Using SQL Worksheet create the following table:
CREATE TABLE OIModel (
modelID int NOT NULL,
logicalURI varchar (255) NOT NULL,
CONSTRAINT pk_OIModel PRIMARY KEY (modelID),
CONSTRAINT logicalURI_OIModel UNIQUE (logicalURI)
3. Run the following program:
package test;
import java.sql.*;
public class Test {
public static void main(String[] args) throws Exception {
java.util.Locale.setDefault(java.util.Locale.US);
Class.forName("oracle.jdbc.OracleDriver");
Connection connection=DriverManager.getConnection("jdbc:oracle:thin:@schlange:1521:ORCL","kaon","kaon");
DatabaseMetaData dmd=connection.getMetaData();
System.out.println("Product version:");
System.out.println(dmd.getDatabaseProductVersion());
System.out.println();
connection.setAutoCommit(false);
connection.setTransactionIsolation(Connection.TRANSACTION_SERIALIZABLE);
int batches=0;
int counter=2000;
for (int outer=0;outer<50;outer++) {
for (int i=0;i<200;i++) {
executeUpdate(connection,"INSERT INTO OIModel (modelID,logicalURI) VALUES ("+counter+",'start"+counter+"')");
executeUpdate(connection,"UPDATE OIModel SET logicalURI='next"+counter+"' WHERE modelID="+counter);
counter++;
connection.commit();
System.out.println("Batch "+batches+" done");
batches++;
protected static void executeUpdate(Connection conn,String sql) throws Exception {
Statement s=conn.createStatement();
try {
int result=s.executeUpdate(sql);
if (result!=1)
throw new Exception("Should update one row, but updated "+result+" rows, query is "+sql);
finally {
s.close();
The program prints the following output:
Product version:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
Batch 0 done
Batch 1 done
java.lang.Exception: Should update one row, but updated 0 rows, query is UPDATE OIModel SET logicalURI='next2571' WHERE modelID=2571
     at test.Test.executeUpdate(Test.java:35)
     at test.Test.main(Test.java:22)
That is, after several iterations, the executeUpdate() method returns 0, rather than 1. This is clearly an error.
4. Leave the database as is. Replace the line
int counter=2000;
with line
int counter=4000;
and restart the program. The following output is generated:
Product version:
Oracle9i Enterprise Edition Release 9.2.0.1.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.1.0 - Production
Batch 0 done
Batch 1 done
java.sql.SQLException: ORA-08177: can't serialize access for this transaction
     at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
     at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
     at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:573)
     at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1891)
     at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1093)
     at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2047)
     at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:1940)
     at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2709)
     at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:796)
     at test.Test.executeUpdate(Test.java:33)
     at test.Test.main(Test.java:22)
This is clearly an error - only one transaction is being active at the time, so there is no need for serialization of transactions.
5. You can restart the program as many times you wish (by chaging the initial counter value first). The same error (can't serialize access for this transaction) will be generated.
6. The error doesn't occur if the transaction isolation level isn't changed.
7. The error doesn't occur if the UPDATE statement is commented out.
Sincerely yours
     Boris Motik

Answer 1

I have a similar problem
I'm using Oracle and serializable isolation level.
Transaction inserts 4000 objects and then updates about 1000 of these objects.
Transactions sees inserted objects but cant update them (row not found or can't serialize access for this transaction are thrown).
On 3 tries for this transaction 1 succeds and 2 fails with one of above errors.
No other transactions run concurently.
In read commited isolation error doesn't arise.
I'm using plain JDBC.
Similar or even much bigger serializable transaction works perfectly on the same database as plsql procedure.
I've tried oci and thin (Oracle) drivers and oranxo demo (i-net) driver.
And this problems arises on all of this drivers.
This problem confused me so much :(.
Maby one of Oracle users, developers nows cause of this strange behaviour.
Thanx for all answers.