Query Connection Isolation Levels

I can do SA_CONN_LOCKS and get the information of all the connections. I have all the connection numbers.
I then need a way to determine the ISOLATION LEVEL of each of the connections. We use a different ISOLATION LEVEL and we want to make sure that isolation level is proper for all connections to stop freezing.
I'm sure I can get the isolation level of the current connection (ITSELF) ---
1. How do I get the isolation level of my own connection?
2. How do I get the isolation levels of all the other connections? (If I have to do it manually for each connection, that's not an issue for me)
Please help!
We are setting an EXECLUSIVE lock on a table which is causing all the other workstations to freeze, and I'm sure that we are setting the isolation level to stop this from happening when opening all the connections - so for some reason, something is getting set back or the user is creating other custom connections and locking records.
Thank you.
Sybase SQL Anywhere 12.01

Hi Robert,
I have logged the incident with support. We haven't move much towards resolution on that side, but we have on our side.
If you're ever finding that an incident needs more attention to it or that you are not receiving an urgent reply from SAP, there is a mechanism to have the SAP Customer Interaction Center involved and for the incident to be flagged at higher support levels, if the production situation warrants it - see: https://websmp106.sap-ag.de/call1sap
The query runs just fine! It runs in 3 seconds.
If we put those two lines back - the query freezes and can sit there forever.
On the surface, this doesn't sound like a locking issue, but more of a performance issue with those views/tables. Especially if you are using isolation level 0.
They asked us to do logging (your SAP SUPPORT) and we did ..... we gave it to them and they came back and told us it could have to do with some known bug called "Issue with parallelism and we can test this by setting the max_query_tasks to 1"
Yes, after reviewing the incident I can see that we have requested and you have performed and provided us with some request logging, and after reviewing this information we had found that there were large table scans inside queries with intra-query parallelism involved (indicating a performance issue). To diagnose the performance issue further, we have requested graphical plans with statistics from these queries to see in more detail about why we are picking the query plans we are at that time. The optimizer uses statistical analysis to pick plans so therefore we need to understand the statistics behind its decisions.
The above suggestion was provided as an interim diagnostic test in order to determine if the behaviour is related to known fixed issues related to intra-query parallelism on earlier builds of 12.0.1. Providing the specific build number of 12.0.1 would avoid needing to run the diagnostic test.
However, if you are convinced that locking is truly the root issue of your problem, please provide the full output of sa_locks() at this time - there should be 11 columns, including the 'lock_type' information which would provide the type of object that is being locked:
conn_name,conn_id,user_id,table_type,creator,table_name,index_id,lock_class,lock_duration,lock_type,row_identifier
If you are over 1000 locks, you will need to increase the 'max_locks' argument to sa_locks().
I have also noted that you have also just provided a response to us in the incident shortly after posting here. Please continue to use the support incident to work with us directly for the diagnostic discussion and your resolution options.
Regards,
Jeff Albion
SAP Active Global Support

Similar Messages

C How to Set Isolation Level in the Connection String

How to Set Isolation Level in the Connection String using the "Microsoft OLE DB Provider for DB2 Version 4.0"?
We are trying to move from Crystal Reporting that run against a IBM DB2 database on a mainfram to SSRS reporting and we have downloaded the "Microsoft OLE DB Provider for DB2 Version 4.0" and then worked with the DB2 Administrator to create the
Packages. We only have access to use the "Read Uncommitted ("MSUR001") package. We were able to connect and pull data before he removed access to the other packages, but after setting access the Connection keeps trying to use
the 'Cursor Stability (MSCS001)" package. How do we change the Default to the "Read Uncommitted ("MSUR001") package??? Since it is keeps defaulting to the the other package
we can't connect to do it in the T-SQL query, it has to be set at the Connection String level.

Hi Dannyboy1263,
According to your description, you want to set the Transaction Isolation Level in Connection String. Right?
In Reporting Services, the Connection String for OLE DB Connection can only contains Provider, Data Source and Initial Catalog. There's no property for setting Transaction Isolation Level in the Connection String. Based on my knowledge, we can
only set the Transaction Isolation Level at Query level or set it by using code (C#, VB, Java...) to call the property of Connection. So unfortunately your requirement can't be achieved currently.
Reference:
OLE DB Connection Type (SSRS)
Data Connections, Data Sources, and Connection Strings in Reporting Services
If you have any question, please feel free to ask.
Best Regards,
Simon Hou

SQL Query help ( On connect By level clause)

Hi all,
I have this query developed with data in with clause.
With dat As
select '@AAA @SSS @DDD' col1 from dual union all
select '@ZZZ @XXX @TTT @RRR @ZZA' col1 from dual
Select regexp_substr( col1 , '[^@][A-Z]+',1,level) Show from dat
connect by level <= regexp_count(col1, '@');Current output :-
SHOW
AAA
SSS
DDD
RRR
ZZA
TTT
RRR
ZZA
XXX
DDD
RRR
SHOW
ZZA
TTT
RRR
ZZA
. . .1st row comes fine, But next row data is getting duplicated. And total record count = 30. I tried with some but didn't work.
Expected output :-
SHOW
AAA
SSS
DDD
ZZZ
XXX
TTT
RRR
ZZAI need some change on my query and I am not able to find that. So anybody can add on that or can also provide some different solution too.
Thanks!
Ashutosh

Hi,
When you use something like "CONNECT BY LEVEL <= x", then at least one of the following must be true:
(a) the table has no more than 1 row
(b) there are other conditions in the CONNECT BY clause, or
(c) you know what you are doing.
To help see why, run this query
SELECT     SYS_CONNECT_BY_PATH (dname, '/')     AS path
,     LEVEL
FROM     scott.dept
CONNECT BY     LEVEL <= 3
;and study the results:
PATH                                     LEVEL
/ACCOUNTING                                  1
/ACCOUNTING/ACCOUNTING                       2
/ACCOUNTING/ACCOUNTING/ACCOUNTING            3
/ACCOUNTING/ACCOUNTING/RESEARCH              3
/ACCOUNTING/ACCOUNTING/SALES                 3
/ACCOUNTING/ACCOUNTING/OPERATIONS            3
/ACCOUNTING/RESEARCH                         2
/ACCOUNTING/RESEARCH/ACCOUNTING              3
/ACCOUNTING/RESEARCH/RESEARCH                3
/ACCOUNTING/RESEARCH/SALES                   3
/ACCOUNTING/RESEARCH/OPERATIONS              3
/ACCOUNTING/SALES                            2
/ACCOUNTING/SALES/ACCOUNTING                 3
84 rows selected.

Connect by level query is taking too long time to run

Hello,
I have a query that returns quarters (YYYYQ) of a begin- and enddate within a specific id, that is built with a connect by level clause, but the query is running to long. I have used explain plan to see what the query is doing, but no silly things to see, just a full table scan, with low costs.
This is the query:
select to_char(add_months( cpj.crpj_start_date,3*(level - 1)),'YYYYQ') as sales_quarter
, cpj.crpj_id as crpj_id
from mv_gen_cra_projects cpj
where cpj.crpj_start_date >= to_date('01/01/2009','mm/dd/yyyy')
and cpj.crpj_start_date <= cpj.crpj_end_date
and cpj.crpj_routing_type = 'A'
and ( cpj.crpj_multi_artist_ind = 'N'
or cpj.crpj_multi_artist_ind is null)
connect by level <= 1 + ceil(months_between(cpj.crpj_end_date,cpj.crpj_start_date)/3);
The result have to be like this:
SALES_QUARTER CRPJ_ID
20091 100
20092 100
20093 100
20094 100
20101 100
20102 100
Can anyone help me out with this?

but no silly things to see, just a full table scan, with low costs.Well, maybe an index scan would be faster?
However:
You will need to provide us some more details, like:
- database version (the result of: SQL> select * from v$version;)
- post the explain plan output (put the tag before and after it, so indentation and formatting are maintained, see the [FAQ|http://forums.oracle.com/forums/help.jspa] for more explanation regarding tags )
- what are your optimizer settings (the result of: SQL> show parameter optimizer)
- if applicable: are your table statistics up to date?
- mv_gen_cra_projects is a materialized view perhaps?
Edited by: hoek on Jan 26, 2010 10:50 AM

Restore default isolation level fails with connection in pool

Hi,
I am developing an application that needs to set the TransactionIsolation to SERIALIZE for a transaction. Setting the TransactionIsolation is not the problem. After this transaction is committed or rolled back, i set the isolation level back to the default i saved before.
The code gets executed and throws no exception. The connection i used is released into the pool. The next time i get this connection from the pool the isolation level is already SERIALIZE. This is not what i wanted to achieve.
It has to be possible to change the isolation level for transaction, isn´t it?
Here is the code, that i use. The ConnectionManager gets the connection from a connection pool i configured in the jdbc connector service. Excep for this issue any other operation works fine.
                ConnectionManager connectionManager = new ConnectionManager();
          Connection con = null;
          int transactionIsolationLevel = 0;
          Queue queue = null;
          List list = null;
          try {
               con = connectionManager.getConnection();
               transactionIsolationLevel = con.getTransactionIsolation();
               if( logger.isInfoEnabled())
                    logger.info(LOGLOC + "ISOLATION_LEVEL default: " + transactionIsolationLevel);
               // auskommentiert für RE
               con.setTransactionIsolation( Connection.TRANSACTION_SERIALIZABLE );
               con.setAutoCommit( false );
          QueueManager queueManager = new QueueManager();
          list = queueManager.GetQueueEntriesBySizeGroups( con, small, medium, large, serverNode );
          con.commit();
          } catch (ClassNotFoundException cnfe) {
               logger.error(LOGLOC + "Exception setting up transaction context for queue service!", cnfe);
               handleExceptions(queue, cnfe);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } catch (SQLException sqle) {
               logger.error(LOGLOC + "Exception setting up transaction context for queue service!", sqle);
               handleExceptions(queue, sqle);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } catch (QueueManagerException qme) {
               logger.error(LOGLOC + "Exception executing queue manager!", qme);
               handleExceptions(queue, qme);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } finally {
               try {
                    con.setAutoCommit(true);
                    if( logger.isInfoEnabled())
                         logger.info(LOGLOC + "ISOLATION_LEVEL before setting default: " + con.getTransactionIsolation() + " now setting: " + transactionIsolationLevel );
                    // Auskommentiert für RE
                    con.setTransactionIsolation( transactionIsolationLevel );
                    con.close();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception setting up transaction context for queue service!", e);
The datasource is a simple jdbc1.x Oracle Datasource with no special settings.
In a remote debugging session i saw, that the wrapped Connection from the datasource sets the txLevel successfully, But the underlying T4Connection does not get this isolation level. Could this be a bug?
Any hints, solutions?

Hi,
I am developing an application that needs to set the TransactionIsolation to SERIALIZE for a transaction. Setting the TransactionIsolation is not the problem. After this transaction is committed or rolled back, i set the isolation level back to the default i saved before.
The code gets executed and throws no exception. The connection i used is released into the pool. The next time i get this connection from the pool the isolation level is already SERIALIZE. This is not what i wanted to achieve.
It has to be possible to change the isolation level for transaction, isn´t it?
Here is the code, that i use. The ConnectionManager gets the connection from a connection pool i configured in the jdbc connector service. Excep for this issue any other operation works fine.
                ConnectionManager connectionManager = new ConnectionManager();
          Connection con = null;
          int transactionIsolationLevel = 0;
          Queue queue = null;
          List list = null;
          try {
               con = connectionManager.getConnection();
               transactionIsolationLevel = con.getTransactionIsolation();
               if( logger.isInfoEnabled())
                    logger.info(LOGLOC + "ISOLATION_LEVEL default: " + transactionIsolationLevel);
               // auskommentiert für RE
               con.setTransactionIsolation( Connection.TRANSACTION_SERIALIZABLE );
               con.setAutoCommit( false );
          QueueManager queueManager = new QueueManager();
          list = queueManager.GetQueueEntriesBySizeGroups( con, small, medium, large, serverNode );
          con.commit();
          } catch (ClassNotFoundException cnfe) {
               logger.error(LOGLOC + "Exception setting up transaction context for queue service!", cnfe);
               handleExceptions(queue, cnfe);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } catch (SQLException sqle) {
               logger.error(LOGLOC + "Exception setting up transaction context for queue service!", sqle);
               handleExceptions(queue, sqle);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } catch (QueueManagerException qme) {
               logger.error(LOGLOC + "Exception executing queue manager!", qme);
               handleExceptions(queue, qme);
               try {
                    con.rollback();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception rolling back transaction!", e);
          } finally {
               try {
                    con.setAutoCommit(true);
                    if( logger.isInfoEnabled())
                         logger.info(LOGLOC + "ISOLATION_LEVEL before setting default: " + con.getTransactionIsolation() + " now setting: " + transactionIsolationLevel );
                    // Auskommentiert für RE
                    con.setTransactionIsolation( transactionIsolationLevel );
                    con.close();
               } catch (SQLException e) {
                    logger.error(LOGLOC + "Exception setting up transaction context for queue service!", e);
The datasource is a simple jdbc1.x Oracle Datasource with no special settings.
In a remote debugging session i saw, that the wrapped Connection from the datasource sets the txLevel successfully, But the underlying T4Connection does not get this isolation level. Could this be a bug?
Any hints, solutions?

Performance issue with connect by level query

Hi I have a problem with connect by level in oracle.
My table is :
J_USER_CALENDAR
USER_NAME     FROM_DATE     TO_DATE     COMMENTS
Uma Shankar     2-Nov-09     5-Nov-09     Comment1
Veera     11-Nov-09     13-Nov-09     Comment2
Uma Shankar     15-Dec-09     17-Dec-09     Commnet3
Vinod     20-Oct-09     21-Oct-09     Comments4
The above table is the user leave calendar.
Now I need to display the users who are on leave between 01-Nov-2009 to 30-Nov-2009
The output should look like:
USER_NAME     FROM_DATE     COMMENTS
Uma Shankar     2-Nov-09     Comment1
Uma Shankar     3-Nov-09     Comment1
Uma Shankar     4-Nov-09     Comment1
Uma Shankar     5-Nov-09     Comment1
Veera     11-Nov-09     Comment2
Veera     12-Nov-09     Comment2
Veera     13-Nov-09     Comment2
For this I have tried with following query , but it is taking too long time to execute.
select FROM_DATE,user_name,comments from (SELECT distinct FROM_DATE,user_name ,
comments FROM (SELECT (LEVEL) + FROM_DATE-1 FROM_DATE,TO_DATE, FIRST_NAME||' '|| LAST_NAME
user_name ,COMMENTS FROM J_USER_CALENDAR
where
and J_USER_CALENDAR.IS_DELETED=0
CONNECT BY LEVEL <= TO_DATE - FROM_DATE+1) a )where (FROM_DATE = '01-Nov-2009' or FROM_DATE = '30-Nov-2009'
or FROM_DATE between '01-Nov-2009' and '30-Nov-2009') order by from_Date ,lower(user_name)
Please help me.
Thanks in advance.
Regards,
Phanikanth

I have not attempted to analyze your SQL statement.
Here is a test set up:
CREATE TABLE T1(
USERNAME VARCHAR2(30),
FROM_DATE DATE,
TO_DATE DATE,
COMMENTS VARCHAR2(100));
INSERT INTO T1 VALUES ('Uma Shankar', '02-Nov-09','05-Nov-09','Comment1');
INSERT INTO T1 VALUES ('Veera','11-Nov-09','13-Nov-09','Comment2');
INSERT INTO T1 VALUES ('Uma Shankar','15-Dec-09','17-Dec-09','Commnet3');
INSERT INTO T1 VALUES ('Vinod','20-Oct-09','21-Oct-09','Comments4');
INSERT INTO T1 VALUES ('Mo','20-Oct-09','05-NOV-09','Comments4');
COMMIT;Note that I included one additional row, where the person starts their vacation in the previous month and ends in the month of November.
You could approach the problem like this:
Assume that you would like to list all of the days of a particular month:
SELECT
TO_DATE('01-NOV-2009','DD-MON-YYYY')+(ROWNUM-1) MONTH_DAY
FROM
DUAL
CONNECT BY
LEVEL<=ADD_MONTHS(TO_DATE('01-NOV-2009','DD-MON-YYYY'),1)-TO_DATE('01-NOV-2009','DD-MON-YYYY');Note that the above attempts to calculate the number of days in the month of November - if it is known that the month has a particular number of days, 30 for instance, you could rewrite the CONNECT BY clause like this:
CONNECT BY
LEVEL<=30Now, we need to pick up those rows of interest from the table:
SELECT
FROM
T1 T
WHERE
(T.FROM_DATE BETWEEN TO_DATE('01-NOV-2009','DD-MON-YYYY') AND TO_DATE('30-NOV-2009','DD-MON-YYYY')
    OR T.TO_DATE BETWEEN TO_DATE('01-NOV-2009','DD-MON-YYYY') AND TO_DATE('30-NOV-2009','DD-MON-YYYY'));
USERNAME        FROM_DATE TO_DATE   COMMENTS
Uma Shankar     02-NOV-09 05-NOV-09 Comment1
Veera           11-NOV-09 13-NOV-09 Comment2
Mo              20-OCT-09 05-NOV-09 Comments4If we then join the two resultsets, we have the following query:
SELECT
FROM
T1 T,
(SELECT
    TO_DATE('01-NOV-2009','DD-MON-YYYY')+(ROWNUM-1) MONTH_DAY
FROM
    DUAL
CONNECT BY
    LEVEL<=ADD_MONTHS(TO_DATE('01-NOV-2009','DD-MON-YYYY'),1)-TO_DATE('01-NOV-2009','DD-MON-YYYY')) V
WHERE
(T.FROM_DATE BETWEEN TO_DATE('01-NOV-2009','DD-MON-YYYY') AND TO_DATE('30-NOV-2009','DD-MON-YYYY')
    OR T.TO_DATE BETWEEN TO_DATE('01-NOV-2009','DD-MON-YYYY') AND TO_DATE('30-NOV-2009','DD-MON-YYYY'))
AND V.MONTH_DAY BETWEEN T.FROM_DATE AND T.TO_DATE
ORDER BY
USERNAME,
MONTH_DAY;
USERNAME        FROM_DATE TO_DATE   COMMENTS   MONTH_DAY
Mo              20-OCT-09 05-NOV-09 Comments4 01-NOV-09
Mo              20-OCT-09 05-NOV-09 Comments4 02-NOV-09
Mo              20-OCT-09 05-NOV-09 Comments4 03-NOV-09
Mo              20-OCT-09 05-NOV-09 Comments4 04-NOV-09
Mo              20-OCT-09 05-NOV-09 Comments4 05-NOV-09
Uma Shankar     02-NOV-09 05-NOV-09 Comment1   02-NOV-09
Uma Shankar     02-NOV-09 05-NOV-09 Comment1   03-NOV-09
Uma Shankar     02-NOV-09 05-NOV-09 Comment1   04-NOV-09
Uma Shankar     02-NOV-09 05-NOV-09 Comment1   05-NOV-09
Veera           11-NOV-09 13-NOV-09 Comment2   11-NOV-09
Veera           11-NOV-09 13-NOV-09 Comment2   12-NOV-09
Veera           11-NOV-09 13-NOV-09 Comment2   13-NOV-09Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

How do you determine a process or sessions isolation level.

We are using COM+ components to issue database statements against an Oracle 8i database. COM+ has a property that allows you to set the isolation level. Is there any tool or query that would allow me to verify the isolation level in use by a session or process? I want to verify this property is actually affecting the connection to the DB.
Thanks,
Sam

FLAG is just one of those columns that Oracle uses. It isn't documented but, as far as I know (which isn't very far), the only use for it is to record the isolation level for the transaction.
I didn't mention it because I didn't think it helped you, for this reason: we don't get a record in the v$transaction view until the transaction has already started. At which point it is too late to change the ISOLATION_LEVEL for the transaction.
Although I suppose you could do this:
BEGIN
   UPDATE dummy_table set col1 = col1;
   -- remember V$TRANSACTION shows all txns
   SELECT count(1) INTO ln
   FROM   v$transaction t, v$session s
   WHERE bitand(t.flag,268435456) <> 0
   AND    s.taddr = t.addr
   AND    s.audsid = sys_context('userenv', 'sessionid');
   IF ln = 0
   THEN
      ROLLBACK;
      SET TRANSACTION ISOLATION LEVEL SERIALIZABLE;
   END IF;
   -- do_whatever
   COMMIT;
END ;.
Cheers, APC

Bug in Oracle's handling of transaction isolation levels?

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

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.

Setting isolation level fails

Hi,
Im using Kodo 3.0.0 on Oracle 8.1.7.
I tried to define the isolation level in the kodo.properties:
e.g.: kodo.jdbc.TransactionIsolation: serializable
Unfortunately Oracle throws an exception which says, that "set
transaction" has to be the first statement called within a transaction. I
get this exception on almost every db access.
java.sql.SQLException: ORA-01453: SET TRANSACTION muss erste Anweisung der
Transaktion sein
at
kodo.jdbc.sql.SQLExceptions.getFatalDataStore(SQLExceptions.java:42)
at
kodo.jdbc.sql.SQLExceptions.getFatalDataStore(SQLExceptions.java:24)
at
kodo.jdbc.schema.LazySchemaFactory.findTable(LazySchemaFactory.java:1
50)
at
kodo.jdbc.meta.VerticalClassMapping.fromMappingInfo(VerticalClassMapp
ing.java:135)
at
kodo.jdbc.meta.RuntimeMappingProvider.getMapping(RuntimeMappingProvid
er.java:56)
at
kodo.jdbc.meta.MappingRepository.getMappingInternal(MappingRepository
java:342)
at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:29
7)
at
kodo.jdbc.meta.MappingRepository.getMappingInternal(MappingRepository
java:325)
at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:29
7)
at
kodo.jdbc.meta.MappingRepository.getMappings(MappingRepository.java:2
72)
at
kodo.jdbc.meta.MappingRepository.getMetaDatas(MappingRepository.java:
256)
at kodo.query.AbstractQuery.internalCompile(AbstractQuery.java:538)
at kodo.query.AbstractQuery.compile(AbstractQuery.java:502)
at kodo.datacache.CacheAwareQuery.compile(CacheAwareQuery.java:265)
-- Wolfgang

Marc,
Here you go...
kodo.util.FatalDataStoreException: ORA-01453: SET TRANSACTION must be
first statement of transaction
     at
kodo.runtime.PersistenceManagerImpl.beforeCompletion(PersistenceManagerImpl.java:897)
     at kodo.runtime.LocalManagedRuntime.commit(LocalManagedRuntime.java:69)
     at
kodo.runtime.PersistenceManagerImpl.commit(PersistenceManagerImpl.java:566)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.initTestModel(AbstractConcurrentAction.java:290)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction$InitRunnable.run(AbstractConcurrentAction.java:212)
     at
edu.sjsu.recon.util.ConcurrencyUtilities.executeSynchronized(ConcurrencyUtilities.java:20)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.setup(AbstractConcurrentAction.java:75)
     at
edu.sjsu.recon.execution.ServerExecutor.beforeExecute(ServerExecutor.java:27)
     at
edu.sjsu.recon.execution.AbstractExecutor.execute(AbstractExecutor.java:43)
     at
edu.sjsu.recon.execution.DefaultExecutionCoordinator.executeAction(DefaultExecutionCoordinator.java:25)
     at
edu.sjsu.recon.server.handler.ExecutionRequestHandler.handleRequest(ExecutionRequestHandler.java:63)
     at edu.sjsu.recon.server.RequestProcessor.run(RequestProcessor.java:90)
NestedThrowablesStackTrace:
kodo.util.DataStoreException: ORA-01453: SET TRANSACTION must be first
statement of transaction
     at
kodo.jdbc.sql.DBDictionary.newDataStoreException(DBDictionary.java:3004)
     at kodo.jdbc.sql.SQLExceptions.getDataStore(SQLExceptions.java:77)
     at kodo.jdbc.sql.SQLExceptions.getDataStore(SQLExceptions.java:63)
     at kodo.jdbc.sql.SQLExceptions.getDataStore(SQLExceptions.java:43)
     at kodo.jdbc.runtime.JDBCStoreManager.connect(JDBCStoreManager.java:871)
     at
kodo.jdbc.runtime.JDBCStoreManager.retainConnection(JDBCStoreManager.java:189)
     at kodo.jdbc.runtime.JDBCStoreManager.begin(JDBCStoreManager.java:114)
     at
kodo.runtime.DelegatingStoreManager.begin(DelegatingStoreManager.java:95)
     at
kodo.runtime.PersistenceManagerImpl.flushInternal(PersistenceManagerImpl.java:1004)
     at
kodo.runtime.PersistenceManagerImpl.beforeCompletion(PersistenceManagerImpl.java:885)
     at kodo.runtime.LocalManagedRuntime.commit(LocalManagedRuntime.java:69)
     at
kodo.runtime.PersistenceManagerImpl.commit(PersistenceManagerImpl.java:566)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.initTestModel(AbstractConcurrentAction.java:290)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction$InitRunnable.run(AbstractConcurrentAction.java:212)
     at
edu.sjsu.recon.util.ConcurrencyUtilities.executeSynchronized(ConcurrencyUtilities.java:20)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.setup(AbstractConcurrentAction.java:75)
     at
edu.sjsu.recon.execution.ServerExecutor.beforeExecute(ServerExecutor.java:27)
     at
edu.sjsu.recon.execution.AbstractExecutor.execute(AbstractExecutor.java:43)
     at
edu.sjsu.recon.execution.DefaultExecutionCoordinator.executeAction(DefaultExecutionCoordinator.java:25)
     at
edu.sjsu.recon.server.handler.ExecutionRequestHandler.handleRequest(ExecutionRequestHandler.java:63)
     at edu.sjsu.recon.server.RequestProcessor.run(RequestProcessor.java:90)
NestedThrowablesStackTrace:
java.sql.SQLException: ORA-01453: SET TRANSACTION must be first statement
of transaction
     at
oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:125)
     at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:305)
     at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:272)
     at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:623)
     at oracle.jdbc.driver.T4CStatement.doOall8(T4CStatement.java:112)
     at oracle.jdbc.driver.T4CStatement.execute_for_rows(T4CStatement.java:474)
     at
oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1028)
     at oracle.jdbc.driver.OracleStatement.execute(OracleStatement.java:1516)
     at
oracle.jdbc.driver.PhysicalConnection.setTransactionIsolation(PhysicalConnection.java:1412)
     at
com.solarmetric.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:266)
     at
com.solarmetric.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:266)
     at
com.solarmetric.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:266)
     at
com.solarmetric.jdbc.DelegatingConnection.setTransactionIsolation(DelegatingConnection.java:266)
     at
com.solarmetric.jdbc.ConfiguringConnectionDecorator.decorate(ConfiguringConnectionDecorator.java:93)
     at
com.solarmetric.jdbc.DecoratingDataSource.decorate(DecoratingDataSource.java:90)
     at
com.solarmetric.jdbc.DecoratingDataSource.getConnection(DecoratingDataSource.java:82)
     at
com.solarmetric.jdbc.DelegatingDataSource.getConnection(DelegatingDataSource.java:131)
     at
kodo.jdbc.schema.DataSourceFactory$DefaultsDataSource.getConnection(DataSourceFactory.java:305)
     at
kodo.jdbc.runtime.JDBCStoreManager.connectInternal(JDBCStoreManager.java:887)
     at kodo.jdbc.runtime.JDBCStoreManager.connect(JDBCStoreManager.java:865)
     at
kodo.jdbc.runtime.JDBCStoreManager.retainConnection(JDBCStoreManager.java:189)
     at kodo.jdbc.runtime.JDBCStoreManager.begin(JDBCStoreManager.java:114)
     at
kodo.runtime.DelegatingStoreManager.begin(DelegatingStoreManager.java:95)
     at
kodo.runtime.PersistenceManagerImpl.flushInternal(PersistenceManagerImpl.java:1004)
     at
kodo.runtime.PersistenceManagerImpl.beforeCompletion(PersistenceManagerImpl.java:885)
     at kodo.runtime.LocalManagedRuntime.commit(LocalManagedRuntime.java:69)
     at
kodo.runtime.PersistenceManagerImpl.commit(PersistenceManagerImpl.java:566)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.initTestModel(AbstractConcurrentAction.java:290)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction$InitRunnable.run(AbstractConcurrentAction.java:212)
     at
edu.sjsu.recon.util.ConcurrencyUtilities.executeSynchronized(ConcurrencyUtilities.java:20)
     at
edu.sjsu.recon.contribution.action.jdo.v10.kodo.v32.oracle.v101.simple.concurrency.AbstractConcurrentAction.setup(AbstractConcurrentAction.java:75)
     at
edu.sjsu.recon.execution.ServerExecutor.beforeExecute(ServerExecutor.java:27)
     at
edu.sjsu.recon.execution.AbstractExecutor.execute(AbstractExecutor.java:43)
     at
edu.sjsu.recon.execution.DefaultExecutionCoordinator.executeAction(DefaultExecutionCoordinator.java:25)
     at
edu.sjsu.recon.server.handler.ExecutionRequestHandler.handleRequest(ExecutionRequestHandler.java:63)
     at edu.sjsu.recon.server.RequestProcessor.run(RequestProcessor.java:90)
Marc Prud'hommeaux wrote:
Cleo-
Can you post the complete stack (including all the nested stack traces)?
In article <[email protected]>, Cleo wrote:
Marc,
Here is the stack:
ORA-01453: SET TRANSACTION must be first statement of transaction
kodo.util.FatalDataStoreException
     at
kodo.runtime.PersistenceManagerImpl.beforeCompletion(PersistenceManagerImpl.java:897)
     at kodo.runtime.LocalManagedRuntime.commit(LocalManagedRuntime.java:69)
     at
kodo.runtime.PersistenceManagerImpl.commit(PersistenceManagerImpl.java:566)
This is the code being executed:
Transaction initTransaction = initPersistenceManager.currentTransaction();
initTransaction.begin();
initPersistenceManager.makePersistentAll(model);
initTransaction.commit(); //EXCEPTION HERE
initPersistenceManager.close();
thx
Marc Prud'hommeaux wrote:
Cleo-
Can you post the complete stack trace from the exception? I expect it is
different from the one posted previously (which was with a much earlier
version of Kodo).
In article <[email protected]>, Cleo wrote:
Has anybody figured out how to solve this?
I am having the same problem with:
KODO 3.2
Oracle JDBC Dirver 10.1.0.3
thx
PS: (I am on a deadline for the end of this week)
Stephen Kim wrote:
First I would suggest using Kodo 3.0.1. Second I would suggest trying
to use 9.0.1 drivers which work very well with 8.1.7.
Wolfgang Hutya wrote:
Hi,
Im using Kodo 3.0.0 on Oracle 8.1.7.
I tried to define the isolation level in the kodo.properties:
e.g.: kodo.jdbc.TransactionIsolation: serializable
Unfortunately Oracle throws an exception which says, that "set
transaction" has to be the first statement called within a
transaction.
I
get this exception on almost every db access.
java.sql.SQLException: ORA-01453: SET TRANSACTION muss erste
Anweisung
der
Transaktion sein
at
kodo.jdbc.sql.SQLExceptions.getFatalDataStore(SQLExceptions.java:42)
at
kodo.jdbc.sql.SQLExceptions.getFatalDataStore(SQLExceptions.java:24)
at
kodo.jdbc.schema.LazySchemaFactory.findTable(LazySchemaFactory.java:1
50)
at
kodo.jdbc.meta.VerticalClassMapping.fromMappingInfo(VerticalClassMapp
ing.java:135)
at
kodo.jdbc.meta.RuntimeMappingProvider.getMapping(RuntimeMappingProvid
er.java:56)
at
kodo.jdbc.meta.MappingRepository.getMappingInternal(MappingRepository
java:342)
at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:29
7)
at
kodo.jdbc.meta.MappingRepository.getMappingInternal(MappingRepository
java:325)
at
kodo.jdbc.meta.MappingRepository.getMapping(MappingRepository.java:29
7)
at
kodo.jdbc.meta.MappingRepository.getMappings(MappingRepository.java:2
72)
at
kodo.jdbc.meta.MappingRepository.getMetaDatas(MappingRepository.java:
256)
atkodo.query.AbstractQuery.internalCompile(AbstractQuery.java:538)
at kodo.query.AbstractQuery.compile(AbstractQuery.java:502)
atkodo.datacache.CacheAwareQuery.compile(CacheAwareQuery.java:265)
-- Wolfgang
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com
Marc Prud'hommeaux
SolarMetric Inc.
Marc Prud'hommeaux
SolarMetric Inc.

SQLServer Isolation Level Problem?

Since the MSSQLServer driver has trouble when returning explicit cursors, and since the complexitites of one of our procedures requires the use of cursors we have been forced to split a DBMS procedure into two. Ie. we have one method that updates the database and one that retrieves the "return value", ie. a setXXX and then a getXXX method.
The problem is that we sometimes get an empty resultset from the getXXX method. Note that this behaviour is not due to the server code as this error is not present if run directly on the SQLServer (ie, not through the JDBC driver). Now testing to and fro suggests that the error is caused by some sort of parallell behaviour or isolation level trouble in the driver, but what exactly? The thing is, if I insert a pause of a few milliseconds between the two calls it works correctly (of course I cannot place a "random" pause there in production code since the pause will probably vary depending on the underlying hardware). I have tried setting to different TransactionIsolation levels, but get the same result all the time. There is only one linear execution of the code as shown below (no multithreading in the java application).
What I'm wondering is: are there any "switches" to turn in relation to waiting for a a stored procedure to finish execution before the next is called? I would expect this to be implicit, but perhaps the SQLServer runs them in parallell and therefore the second method is called before the first is finished, but then, shouldn't the TransactionIsolationLevel of Serializable hinder this? I would appreciate any help on this one, sample code below, the problem being that wereas the while loop should always print the line it sometimes doesn't since the result is empty (not null, empty). It isn't the parameter to the execute_task either, we get the "missing result" problem with different paramaters that all always work when run directly on the SQLServer (via SQL Query Analyzer).
//Execute the update to the server
CallableStatement execute_task = connection.prepareCall("{call setXXX(?)}");
execute_task.setInt(1, 1);
execute_task.execute();
//Retrieve the task execution results:
CallableStatement show_execute_task = connection.prepareCall("{call getXXX}");
show_execute_task.execute();
ResultSet show_execute_resultset = show_execute_task.getResultSet();
while(show_execute_resultset.next()){
System.out.println("Result received");
}

Since the MSSQLServer driver has trouble when
returning explicit cursors, and since the
complexitites of one of our procedures requires the
use of cursors we have been forced to split a DBMS
procedure into two. Ie. we have one method that
updates the database and one that retrieves the
"return value", ie. a setXXX and then a getXXX method.
The problem is that we sometimes get an empty
resultset from the getXXX method. Note that this
behaviour is not due to the server code as this error
is not present if run directly on the SQLServer (ie,
not through the JDBC driver). Now testing to and fro
suggests that the error is caused by some sort of
parallell behaviour or isolation level trouble in the
driver, but what exactly? The thing is, if I insert a
pause of a few milliseconds between the two calls it
works correctly (of course I cannot place a "random"
pause there in production code since the pause will
probably vary depending on the underlying hardware).
I have tried setting to different
TransactionIsolation levels, but get the same result
all the time. There is only one linear execution of
the code as shown below (no multithreading in the
java application).
What I'm wondering is: are there any "switches" to
turn in relation to waiting for a a stored procedure
to finish execution before the next is called? I would
expect this to be implicit, but perhaps the SQLServer
runs them in parallell and therefore the second methodthis is what i would expect. parallel execution i mean... othewise you might as well use Access...
is called before the first is finished, but then,
shouldn't the TransactionIsolationLevel of
Serializable hinder this? I would appreciate any helpi'm not sure...
t be perfectly honest while i understand the different transaction levels on their face level as described in java.sql.Connection I am not entirely sure WHAT the expected behaviour actually is for each level.
not to get too OT here but for example TRANSACTION_REPEATABLE_READ
if the first transaction reads row 1 from tableA
then a second transaction changes row 1 in table A and commits the changes
the first transaction reads row 1 from table A again... what the heck is supposed to happen. i think it is supposed to read the same values as the first pass even though commited changes have been made but i'm not entirely sure.
on this one, sample code below, the problem being that
wereas the while loop should always print the line it
sometimes doesn't since the result is empty (not null,
empty). It isn't the parameter to the execute_task
either, we get the "missing result" problem with
different paramaters that all always work when run
directly on the SQLServer (via SQL Query Analyzer).
//Execute the update to the server
CallableStatement execute_task =
connection.prepareCall("{call setXXX(?)}");
execute_task.setInt(1, 1);
execute_task.execute();
//Retrieve the task execution results:
CallableStatement show_execute_task =
connection.prepareCall("{call getXXX}");
show_execute_task.execute();
ResultSet show_execute_resultset =
show_execute_task.getResultSet();
while(show_execute_resultset.next()){
System.out.println("Result received");
}i don't really follow your code too well here but here is what i would suggest...
fetch whatever the first procedure returns FIRST.
this should force your app to wait on this before you execute the second one.
does that make sense? it seems simple to me but maybe i'm missing something.

Isolation level in OBIEE

Hi Team,
In RPD connection pool propertie isolation levels there will be 5 levels we can see default,dirty read,commited read,repeatable read,serializable in which cases which level we have to use.Is there is any detailed document or link please post me.
thanks in advance
Edited by: 799666 on May 16, 2011 6:23 AM

Hi,
Committed Read
* Locks are held while the data is read to avoid dirty reads. Data can be changed before the transaction ends with that connection.
* Allows to insert new records and allows to update the records that a transaction isusing and would reflect only after commit, In other words data can be changed before end of transaction resulting in non repeatable reads.
Dirty Read
* Locking. Can read uncommitted or dirty data, change values in data during read process in a transaction. Least restrictive of all types.
* With this option it is possible to read uncommitted data and have rows appear and disappear before end of transaction
Repeatable Read
* Places locks on all data used in a query so that nobody can update the data. However new rows can be inserted by other users but will be available in later reads in the current transaction.
* Allows to insert new records and places the locks on the al the data that is used inthe query to prevent anybody else updating the data.
Serialization
* Places a range lock on data set preventing other users to insert or update the rows in data set until the transaction is complete. Most restrictive of all.
* Locks the dataset and does not allow to insert or update the data set until the transaction is complete.
hope helps u............
Assign points and close thread if answered........
Cheers,
Aravind

CF10 Datasources and Isolation Level

I've been looking all over for a solution to this and have been unable to find one. In CF9 using jrun, we are able to set the default isolation level on a datasource so that any time it is used it defaults to dirty read in case a record is in a lock state it still returns the current data. However in CF10 with it using Tomcat, I cannot find anyway to even configure a datasource through Tomcat, or set the default isolation level on a datasource created in the CF10 administration panel. I know we could surround every single query with a <cftransaction> tag that sets the isolation level, but that is unrealistic as this is a very large web service with thousands of queries.
Can anyone help out with this? Thanks!

Hello
You should be able to see your inserted row in the same session
Session 1:_
SQL> select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
SQL> SELECT * FROM demo;
        ID
        11
         1
         2
         3
         4
         5
         8
         9
        10
9 rows selected.
SQL>
SQL> INSERT INTO demo VALUES (11);
1 row created.
SQL>
SQL> SELECT *   FROM demo;
        ID
        11
         1
         2
         3
         4
         5
         8
         9
        10
        11
10 rows selected.
Session 2: Different session without committing the result from the above session_
Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, Oracle Label Security, OLAP and Data Mining Scoring Engine options
SQL> select * from demo;
        ID
        11
         1
         2
         3
         4
         5
         8
         9
        10
9 rows selected.Regards
Edited by: OrionNet on Jan 4, 2009 9:58 PM

Using Isolation Level Serialazable

I use Visual Basic/Windows Forms to create my project
I have my form for amending orders ready.
The flow is:
Get order number
Open connection
sqlcommand to check if order number exists
if not, return
Set isolation level serialazable
Get response to "Delete full order"
If response is "Yes":
trans = connlock.BeginTransaction("Delete_OA")
qry = "delete from ilprod where iorno1 = " & miorno1.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
trans.Commit()
MessageBox.Show("OA " & miorno1.Text & "Deleted")
if response is no:
I display the order details and items.
if an item is selected, get response to "Delete item?"
if response is yes,
trans = connlock.BeginTransaction("Delete_Item")
qry = "delete from ilprod where csno = " & mcsno.Text & " and itno = " & mitno.Text
Dim cmd As SqlCommand
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
miorno1.Text = 0
MessageBox.Show("Item " & miorno1.Text & "/" & mnitno.Text & "Deleted")
trans.Commit()
and continue amendment.
if response is no: proceed to amend item details etc.
Finally, save amendments:
qry = "select opamno from opcsno"
Dim cmd = New SqlCommand(qry, connlock, trans)
new_amno.Text = cmd.ExecuteScalar() + 1
qry = "update opcsno set opamno = opamno + 1"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "update opmain set "
qry = qry & "DORNO= " & "'" & DORNOTextBox.Text & "'"
qry = qry & ",DORDT = " & "'" & CDate(DORDTDateTimePicker.Value) & "'"
qry = qry & ",SIP1FL = " & SIP1FLTextBox.Text
qry = qry & ",SIP2FL = " & SIP2FLTextBox.Text
qry = qry & ",SIP3FL = " & SIP3FLTextBox.Text
qry = qry & ",STAXFL = " & STAXFLCOMBO.SelectedValue
qry = qry & ",DESTFL = " & DESTFLCOMBO.Text
qry = qry & ",MODEFL = " & MODEFLCOMBO.SelectedValue
qry = qry & ",CARRFL = " & CARRFLCOMBO.SelectedValue
qry = qry & ",PACKFL = " & PACKFL.SelectedValue
qry = qry & ",PAYTFL = " & PAYTFLCOMBO.SelectedValue
qry = qry & ",SCDLFL = 4"
qry = qry & ",AMNO = " & new_amno.Text
qry = qry & ",IRDT = " & "'" & CDate(IRDTDateTimePicker.Value) & "'"
qry = qry & " WHERE csno = " & mcsno.Text & ""
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = " delete from opnarr where csno = " & mcsno.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
If vbTrue Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'A',"
qry = qry & "'" & PAYTFLCOMBO.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
If vbTrue Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'D'" & ","
qry = qry & "'" & STAXFLCOMBO.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
If mmcd = "Z998" Or mmcd = "Z999" Then
qry = "insert into opnarr (csno,narfl,narr,amno) values ("
qry = qry & mcsno.Text & ","
qry = qry & "'X'" & ","
qry = qry & "'" & mname.Text & "'" & ","
qry = qry & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
For Each row In DataGridView1.Rows
If row.selected Then
qry = "update ilprod set qlty = " & row.cells("qlty").value
qry = qry & ",siz1 = " & row.cells("siz1").value & ",siz2 = " & row.cells("siz2").value & ",siz3 = " & row.cells("siz3").value & ",sppr = " & "'" & row.cells("sppr").value & "'"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "update ilprod set pqty = 0, pmtr = 0 where csno = " & mcsno.Text & " and itno = " & mitno.Text & " and pqty < 0"
' This means that qnty will not be equal to inqty+pqty in such records
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
qry = "delete from opscdl " & "where csno = " & mcsno.Text & " and itno = " & mitno.Text
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
For Each scdlrow In DataGridView2.Rows
If scdlrow.cells("csno").value = mcsno.Text And scdlrow.cells("itno").value = mitno.Text And scdlrow.cells("sqnty").value <> 0 Then
qry = "insert into opscdl (csno,itno,sqnty,srmtr,sdate,stype,amno) values (" & scdlrow.cells("csno").value & "," & scdlrow.cells("itno").value & "," & scdlrow.cells("sqnty").value & "," & scdlrow.cells("srmtr").value & "," & "Convert(date,'" & scdlrow.cells("sdate").value & "')" & "," & "'" & scdlrow.cells("stype").value & "'" & "," & new_amno.Text & ")"
cmd = New SqlCommand(qry, connlock, trans)
cmd.ExecuteNonQuery()
End If
Next
End If
Next
trans.Commit()
When I run the form, the Order is amended successfully: but I do not think the isolation level is set correctly: as I can access the order from another (new query) connection when the amendment is going on and not yet saved
There are a large number of commands between accesing the records from SQL and the above Save Commands.
Can Can someone guide me?
To repeat: the flow is
SET ISOLATION LEVEL
GET ORDER NUMBER FROM SCREEN
DELETE ORDER?
DELETE ITEM?
AMEND OA AND SAVE AMENDMENTS
I apologise if the above has been unclear.
Mohan
MohanSQL

Hi Mohan,
As the issue is more related to Visual Basic/Windows Forms programming, I would like to recommend you post the question in the
Visual Basic forum or
Windows Forms forum. It is appropriate and more experts will assist you.
Also, you can check the following articles about starting database transactions with the specified isolation level in Visual Basic or other projects.
SqlConnection.BeginTransaction Method (IsolationLevel)
http://msdn.microsoft.com/en-us/library/5ha4240h(v=vs.110).aspx
ADO.NET Transactions and Concurrency in VB.NET
http://www.dotnetheaven.com/article/ado.net-transactions-and-concurrency-in-vb.net
Thanks,
Lydia Zhang

Changing Isolation Level Mid-Transaction

Hi,
I have a SS bean which, within a single container managed transaction, makes numerous
database accesses. Under high load, we start having serious contention issues
on our MS SQL server database. In order to reduce these issues, I would like
to reduce my isolation requirements in some of the steps of the transaction.
To my knowledge, there are two ways to achieve this: a) specify isolation at the
connection level, or b) use locking hints such as NOLOCK or ROWLOCK in the SQL
statements. My questions are:
1) If all db access is done within a single tx, can the isolation level be changed
back and forth?
2) Is it best to set the isolation level at the JDBC level or to use the MS SQL
locking hints?
Is there any other solution I'm missing?
Thanks,
Sebastien

Galen Boyer wrote:
On Sun, 28 Mar 2004, [email protected] wrote:
Galen Boyer wrote:
On Wed, 24 Mar 2004, [email protected] wrote:
Oracle's serializable isolation level doesn't offer what most
customers I've seen expect it to offer. They typically expect
that a serializable transaction will block any read-data from
being altered during the transaction, and oracle doesn't do
that.I haven't implemented WEB systems that employ anything but
the default concurrency control, because a web transaction is
usually very long running and therefore holding a connection
open during its life is unscalable. But, your statement did
make me curious. I tried a quick test case. IN ONE SQLPLUS
SESSION: SQL> alter session set isolation_level =
serializable; SQL> select * from t1; ID FL ---------- -- 1 AA
2 BB 3 CC NOW, IN ANOTHER SQLPLUS SESSION: SQL> update t1 set
fld = 'YY' where id = 1; 1 row updated. SQL> commit; Commit
complete. Now, back to the previous session. SQL> select *
from t1; ID FL ---------- -- 1 AA 2 BB 3 CC So, your
statement is incorrect.Hi, and thank you for the diligence to explore. No, actually
you proved my point. If you did that with SQLServer or Sybase,
your second session's update would have blocked until you
committed your first session's transaction. Yes, but this doesn't have anything to do with serializable.
This is the weak behaviour of those systems that say writers can
block readers.Weak or strong, depending on the customer point of view. It does guarantee
that the locking tx can continue, and read the real data, and eventually change
it, if necessary without fear of blockage by another tx etc.
In your example, you were able to change and commit the real
data out from under the first, serializable transaction. The
reason why your first transaction is still able to 'see the old
value' after the second tx committed, is not because it's
really the truth (else why did oracle allow you to commit the
other session?). What you're seeing in the first transaction's
repeat read is an obsolete copy of the data that the DBMS
made when you first read it. Yes, this is true.
Oracle copied that data at that time into the per-table,
statically defined space that Tom spoke about. Until you commit
that first transaction, some other session could drop the whole
table and you'd never know it.This is incorrect.Thanks. Point taken. It is true that you could have done a complete delete
of all rows in the table though..., correct?
That's the fast-and-loose way oracle implements
repeatable-read! My point is that almost everyone trying to
serialize transactions wants the real data not to
change. Okay, then you have to lock whatever you read, completely.
SELECT FOR UPDATE will do this for your customers, but
serializable won't. Is this the standard definition of
serializable of just customer expectation of it? AFAIU,
serializable protects you from overriding already committed
data.The definition of serializable is loose enough to allow
oracle's implementation, but non-changing relevant data is
a typically understood hope for serializable. Serializable
transactions typically involve reading and writing *only
already committed data*. Only DIRTY_READ allows any access to
pre-committed data. The point is that people assume that a
serializable transaction will not have any of it's data re
committed, ie: altered by some other tx, during the serializable
tx.
Oracle's rationale for allowing your example is the semantic
arguement that in spite of the fact that your first transaction
started first, and could continue indefinitely assuming it was
still reading AA, BB, CC from that table, because even though
the second transaction started later, the two transactions *so
far*, could have been serialized. I believe they rationalize it by saying that the state of the
data at the time the transaction started is the state throughout
the transaction.Yes, but the customer assumes that the data is the data. The customer
typically has no interest in a copy of the data staying the same
throughout the transaction.
Ie: If the second tx had started after your first had
committed, everything would have been the same. This is true!
However, depending on what your first tx goes on to do,
depending on what assumptions it makes about the supposedly
still current contents of that table, it may ether be wrong, or
eventually do something that makes the two transactions
inconsistent so they couldn't have been serialized. It is only
at this later point that the first long-running transaction
will be told "Oooops. This tx could not be serialized. Please
start all over again". Other DBMSes will completely prevent
that from happening. Their value is that when you say 'commit',
there is almost no possibility of the commit failing. But this isn't the argument against Oracle. The unable to
serialize doesn't happen at commit, it happens at write of
already changed data. You don't have to wait until issuing
commit, you just have to wait until you update the row already
changed. But, yes, that can be longer than you might wish it to
be. True. Unfortunately the typical application writer logic may
do stuff which never changes the read data directly, but makes
changes that are implicitly valid only when the read data is
as it was read. Sometimes the logic is conditional so it may never
write anything, but may depend on that read data staying the same.
The issue is that some logic wants truely serialized transactions,
which block each other on entry to the transaction, and with
lots of DBMSes, the serializable isolation level allows the
serialization to start with a read. Oracle provides "FOR UPDATE"
which can supply this. It is just that most people don't know
they need it.
With Oracle and serializable, 'you pay your money and take your
chances'. You don't lose your money, but you may lose a lot of
time because of the deferred checking of serializable
guarantees.
Other than that, the clunky way that oracle saves temporary
transaction-bookkeeping data in statically- defined per-table
space causes odd problems we have to explain, such as when a
complicated query requires more of this memory than has been
alloted to the table(s) the DBMS will throw an exception
saying it can't serialize the transaction. This can occur even
if there is only one user logged into the DBMS.This one I thought was probably solved by database settings,
so I did a quick search, and Tom Kyte was the first link I
clicked and he seems to have dealt with this issue before.
http://tinyurl.com/3xcb7 HE WRITES: serializable will give you
repeatable read. Make sure you test lots with this, playing
with the initrans on the objects to avoid the "cannot
serialize access" errors you will get otherwise (in other
databases, you will get "deadlocks", in Oracle "cannot
serialize access") I would bet working with some DBAs, you
could have gotten past the issues your client was having as
you described above.Oh, yes, the workaround every time this occurs with another
customer is to have them bump up the amount of that
statically-defined memory. Yes, this is what I'm saying.
This could be avoided if oracle implemented a dynamically
self-adjusting DBMS-wide pool of short-term memory, or used
more complex actual transaction logging. ? I think you are discounting just how complex their logging
is. Well, it's not the logging that is too complicated, but rather
too simple. The logging is just an alternative source of memory
to use for intra-transaction bookkeeping. I'm just criticising
the too-simpleminded fixed-per-table scratch memory for stale-
read-data-fake-repeatable-read stuff. Clearly they could grow and
release memory as needed for this.
This issue is more just a weakness in oracle, rather than a
deception, except that the error message becomes
laughable/puzzling that the DBMS "cannot serialize a
transaction" when there are no other transactions going on.Okay, the error message isn't all that great for this situation.
I'm sure there are all sorts of cases where other DBMS's have
laughable error messages. Have you submitted a TAR?Yes. Long ago! No one was interested in splitting the current
message into two alternative messages:
"This transaction has just become unserializable because
of data changes we allowed some other transaction to do"
or
"We ran out of a fixed amount of scratch memory we associated
with table XYZ during your transaction. There were no other
related transactions (or maybe even users of the DBMS) at this
time, so all you need to do to succeed in future is to have
your DBA reconfigure this scratch memory to accomodate as much
as we may need for this or any future transaction."
I am definitely not an Oracle expert. If you can describe for
me any application design that would benefit from Oracle's
implementation of serializable isolation level, I'd be
grateful. There may well be such.As I've said, I've been doing web apps for awhile now, and
I'm not sure these lend themselves to that isolation level.
Most web "transactions" involve client think-time which would
mean holding a database connection, which would be the death
of a web app.Oh absolutely. No transaction, even at default isolation,
should involve human time if you want a generically scaleable
system. But even with a to-think-time transaction, there is
definitely cases where read-data are required to stay as-is for
the duration. Typically DBMSes ensure this during
repeatable-read and serializable isolation levels. For those
demanding in-the-know customers, oracle provided the select
"FOR UPDATE" workaround.Yep. I concur here. I just think you are singing the praises of
other DBMS's, because of the way they implement serializable,
when their implementations are really based on something that the
Oracle corp believes is a fundamental weakness in their
architecture, "Writers block readers". In Oracle, this never
happens, and is probably one of the biggest reasons it is as
world-class as it is, but then its behaviour on serializable
makes you resort to SELECT FOR UPDATE. For me, the trade-off is
easily accepted.Well, yes and no. Other DBMSes certainly have their share of faults.
I am not critical only of oracle. If one starts with Oracle, and
works from the start with their performance arcthitecture, you can
certainly do well. I am only commenting on the common assumptions
of migrators to oracle from many other DBMSes, who typically share
assumptions of transactional integrity of read-data, and are surprised.
If you know Oracle, you can (mostly) do everything, and well. It is
not fundamentally worse, just different than most others. I have had
major beefs about the oracle approach. For years, there was TAR about
oracle's serializable isolation level *silently allowing partial
transactions to commit*. This had to do with tx's that inserted a row,
then updated it, all in the one tx. If you were just lucky enough
to have the insert cause a page split in the index, the DBMS would
use the old pre-split page to find the newly-inserted row for the
update, and needless to say, wouldn't find it, so the update merrily
updated zero rows! The support guy I talked to once said the developers
wouldn't fix it "because it'd be hard". The bug request was marked
internally as "must fix next release" and oracle updated this record
for 4 successive releases to set the "next release" field to the next
release! They then 'fixed' it to throw the 'cannot serialize' exception.
They have finally really fixed it.( bug #440317 ) in case you can
access the history. Back in 2000, Tom Kyte reproduced it in 7.3.4,
8.0.3, 8.0.6 and 8.1.5.
Now my beef is with their implementation of XA and what data they
lock for in-doubt transactions (those that have done the prepare, but
have not yet gotten a commit). Oracle's over-simple logging/locking is
currently locking pages instead of rows! This is almost like Sybase's
fatal failure of page-level locking. There can be logically unrelated data
on those pages, that is blocked indefinitely from other equally
unrelated transactions until the in-doubt tx is resolved. Our TAR has
gotten a "We would have to completely rewrite our locking/logging to
fix this, so it's your fault" response. They insist that the customer
should know to configure their tables so there is only one datarow per
page.
So for historical and current reasons, I believe Oracle is absolutely
the dominant DBMS, and a winner in the market, but got there by being first,
sold well, and by being good enough. I wish there were more real market
competition, and user pressure. Then oracle and other DBMS vendors would
be quicker to make the product better.
Joe

Locks and Isolation Levels

Hello,
I'm new to the Oracle environment and have just started using PL/SQL on Oracle 8i. Where can I find info on how Oracle locks data and how transaction isolation levels are used? We've still not recvd our manuals so please any replies referring to manuals are not welcome!

You could move forward balance into its own table. That was, the SELECT will not lock on the original table. Most of the running balance schemes that I have seen take a snapshot as of a given date (say, statement printing date) and record both the timestamp and the amount. Next month, you simply get last month's vaule and timestamp and query on transactions after that timestamp.
- Saish

Query Connection Isolation Levels

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