Snapshot isolation transaction aborted due to update conflict
Hi Forum,
Can anyone help me to give the solution for this below problem.
We are developing MVC3 application with SQL Server 2008, we are facing as
Snapshot isolation transaction aborted due to update conflict
Snapshot isolation transaction aborted due to update conflict. You cannot use snapshot isolation to access table 'dbo.Tb_M_Print' directly or indirectly in database 'DB_Production' to update, delete, or insert the row that has been modified or deleted
by another transaction. Retry the transaction or change the isolation level for the update/delete statement .
Please tell me the solution how to proceed for the above problem
Rama
change the isolation level for the update/delete statement .
The error message already mentions the solution.
See also MSDN
Lesson 1: Understanding the Available Transaction Isolation Levels => Update Conflicts
Olaf Helper
[ Blog] [ Xing] [ MVP]
Similar Messages
-
Snapshot isolation in combination with service broker
Hi all,
I'm currently using the service broker in combination with snapshot isolation on the database.
The notification request is executed under read commited isolation. The code looks like this:
SqlDependency dependency = new SqlDependency(command, null, 0);
dependency.OnChange += eventHandler;
using (SqlConnection conn = new SqlConnection(connectionString))
using (SqlTransaction tran = conn.BeginTransaction(IsolationLevel.ReadCommitted))
command.Transaction = tran;
command.ExecuteNonQuery();
tran.Commit();
The request is successfully created and works fine at the first glance.
Now here is my problem:
I created a notification request that should monitor two objects. The query (executed under read committed) looks something like this:
SELECT Id, DataVersion FROM dbo.MyObjects WHERE Id = 1 OR Id = 2
Afterwards I delete both objects in separate nested transactions. Both of them are running under snapshot isolation. It looks something like this:
using (SqlConnection conn1 = new SqlConnection(connectionString))
conn1.Open();
using (SqlTransaction tran1 = connection1.BeginTransaction(IsolationLevel.Snapshot))
using (SqlConnection conn2 = new SqlConnection(connectionString))
conn2.Open();
using (SqlTransaction tran2 = conn2.BeginTransaction(IsolationLevel.Snapshot))
SqlCommand command2 = conn2.CreateCommand();
command2.Transaction = tran2;
command2.CommandText = "DELETE FROM MyObjects WHERE Id = 2";
command2.ExecuteNonQuery();
tran2.Commit();
SqlCommand command1 = conn1.CreateCommand();
command1.CommandText = "DELETE FROM MyObjects WHERE Id = 1";
command1.Transaction = tran1;
command1.ExecuteNonQuery();
tran1.Commit(); //-> Conflict exception
A conflict exception is raised during the commit of last transaction. The conflict seems to occur in the table "sys.query_notifcations_xxxxxxxxx". This is the exact message:
An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
Additional information: Snapshot isolation transaction aborted due to update conflict. You cannot use snapshot isolation to access table 'sys.query_notification_45295271' directly or indirectly in database 'MyDatabase' to update, delete,
or insert the row that has been modified or deleted by another transaction. Retry the transaction or change the isolation level for the update/delete statement.
Is there any restriction for the service broker that prohibits the usage of snapshot isolation.
Thanks in advance.No, the error has nothing to do with Service Broker. Or for that matter, query notifications, which is the feature you are actually using. (Query notifications uses Service Broker, but Service Broker != Query notification.)
You would get the same error if you had a trigger in MyObjects that tried to update the same row for both deletions. A snapshot transaction gives you a consistent view of the database in a certain point in time. Consider this situation:
Snapshot transaction A that started at time T update a row R at time T2. Snapshot transaction B starts at time T1 updates the same row at time T3. Had they been regular non-snapshot transaction, transaction B would have been blocked already when it tried
to read R, but snapshot transactions do not get blocked. But if B would be permitted to update R, the update from transaction A would be lost. Assume that the update is an incremental one, for instance updating cash balance for an account. You can see that
this is not permittable.
In your case, the row R happens to be a row in an internal table for query notifications, but it is the application design which is the problem. There is no obvious reason to use snapshot isolation in your example since you are only deleting. And there is
even less reason to have two transactions and connections for the task.
Erland Sommarskog, SQL Server MVP, [email protected] -
hi,
I have enable snapshot isolation level, in my database all queries execute in read commited isolation only one big transaction uses snapshot isolation.
q1)i wanted to know if snapshot silation transaction is not running but database is enable for snapshot ,then will the normal
queries using read commited will create versions or not.
yours sincerley.Enabling snapshot isolation level on DB level does not change behavior of queries in any other isolation levels. In that option you are eliminating all blocking even between writers (assuming they do not update
the same rows) although it could lead to 3960 errors (data has been modified by other sessions).
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
MS SQL optimization: MS SQL Development and Optimization
MS SQL Consulting:
Large scale of database and data cleansing
Remote DBA Services:
Improves MS SQL Database Performance
SQL Server Integration Services:
Business Intelligence -
Transaction aborted (possibly due to transaction time out) - Question
This one is driving me insane!
Bellow you will find the code, the descriptor stuff and the exception. The code belongs to a CMP EJB using CMT (transactions). This gets called from a session bean. Please help.
Here is the code:
public Object ejbCreate( String id )
throws CreateException {
s_logger.debug( "ejbCreate()" ); // this prits
//setId( id );
return null;
public void ejbPostCreate( String id )
throws CreateException {
s_logger.debug( "ejbPostCreate()" ); // this also prints
here is descriptor stuff:
<container-transaction>
<method>
<ejb-name>AgentBean</ejb-name>
<method-name>*</method-name>
</method>
<trans-attribute>Required</trans-attribute>
</container-transaction>
here is the !@#$ exception (sorry been tracing this one for hours):
RemoteException occurred in server thread; nested exception is:
java.rmi.RemoteException: Transaction aborted (possibly due to transaction time out).; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback; nested exception is:
javax.transaction.RollbackException: Transaction marked for rollback
java.rmi.ServerException: RemoteException occurred in server thread; nested exception is:
java.rmi.RemoteException: Transaction aborted (possibly due to transaction time out).; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback; nested exception is:
javax.transaction.RollbackException: Transaction marked for rollback
java.rmi.RemoteException: Transaction aborted (possibly due to transaction time out).; nested exception is: javax.transaction.RollbackException: Transaction marked for rollback; nested exception is:
javax.transaction.RollbackException: Transaction marked for rollback
javax.transaction.RollbackException: Transaction marked for rollback
<<no stack trace available>>It usually means that you're doing something which creates a loop in your locking. Something like setting a value in each instance from an update method of one of the instances. Your posted code doesn't seem to be the trouble, but I could be missing something.
Success,
S. -
JTA transaction is aborting due to an user rollback fault
Hi,
While testing the ReceiptEBS on EM, we are getting given error, few minutes before EBS was working fine.
Error -
The selected operation CreateReceiptList could not be invoked.
An exception occured while invoking the webservice operation. Please see logs for more details.
oracle.sysman.emSDK.webservices.wsdlapi.SoapTestException: Global retry rollback fault thrown.
The current JTA transaction is aborting due to an user rollback fault being thrown. The upstream component should retry in a new
JTA transaction upon catching this fault.
This exception was caused by a global retry fault being thrown from downstream component. The user had directed the BPEL engine to roll
back the current JTA transaction and retry within new JTA transactions for the specified number of times and retry interval.
There is no action recommended.
oracle.sysman.emSDK.webservices.wsdlapi.SoapTestException: Global retry rollback fault thrown.
The current JTA transaction is aborting due to an user rollback fault being thrown. The upstream component should retry in a
new JTA transaction upon catching this fault.
This exception was caused by a global retry fault being thrown from downstream component. The user had directed the BPEL engine
to roll back the current JTA transaction and retry within new JTA transactions for the specified number of times and retry interval.
There is no action recommended.Hi,
This seems to be a timeout error during JTA transaction. Some of my suggestions are
1. Put a timeout value in the partner link properties.
2. Set the timeout parameter for JTA under Domain configuration in console.
Regards,
Rahul -
Warning: Transaction[....] aborted due to status [1130203]
Recently I have started recieving the following error when trying to run calculations on one of my databases:
Warning: Transaction.... aborted due to status 1130203
Weve been on the same version for over a year and had not seen this before.
My solution as of now is to restart the Essbase service. This seems to "fix" things for a short while. Then it starts back up.
Has anyone else seen this? What is the root cause? Solution?
Thanks,
Dave
Edited by: Dave W on Aug 25, 2009 10:00 AM
Edited by: Dave W on Aug 25, 2009 10:02 AM
Edited by: Dave W on Aug 25, 2009 10:02 AM
Edited by: Dave W on Aug 25, 2009 10:06 AM
Edited by: Dave W on Aug 25, 2009 10:07 AM
Edited by: Dave W on Aug 25, 2009 10:08 AMMight be a memory issue. Fiddle around with a lower cache setting. Try to reduce the block size. Check the rights of the user. You can also try cache memory locking. You can refer to this link.
http://blog.biard.info/2006/11/13/44/
Sayantan -
We have setup snapshot level isolation in our Berkeley DB XML database, and started getting the following errors during queries after a while:
PANIC: Cannot allocate memory
We set the max lockers at 10,000, max locks at 1,000,000 and max lock objects at 1,000,000 as well. We are also very careful to commit or abort every transaction initiated. All of our operations are done under the context of an explicit transaction. Could there be some memory leak? Should we be aware of some other caveats?
Thank you,
Alexander.Hi Alexander,
I would suggest running the application under a memory leak checker/debugger, such as Purify or Valgrind. If you do get something suspicious please report it.
Though, when running with snapshot isolation you have to be prepared for the cost that MVCC (MultiVersion Concurrency Control) implies, that is, larger cache size requirements.
Pages are being duplicated when a writer takes a read lock on a page, therefore operating on a copy of that page. This avoids the situation where other writers would block due to a read lock held on the page, but it also means that the cache will fill up faster. You might need a larger cache in order to hold the entire working set in memory.
Note that the need of more cache is amplified when you have a large number of concurrent active long-running transactions, as it increases the volume of active page versions (copies of pages that cannot safely be freed). In such situation, it may worth trying to run updates at serializable isolation and only run queries at snapshot isolation. The queries will not block updates, or vice versa, and the updates will not force page versions to be kept for long periods.
You should try keeping the transactions running under snapshot isolation as short as possible.
Of course, the recommended approach to resolve this issue is to increase the cache size, if possible. You can estimate how large your cache should be by taking a checkpoint, followed by a call to the DB_ENV->log_archive() method. The amount of cache required is approximately double the size of the remaining log files (that is, the log files that cannot be archived).
Also, along with increasing the cache size you may need to increase the number of maximum active transactions that the application supports.
Please review the following places for further information:
[http://www.oracle.com/technology/documentation/berkeley-db/db/programmer_reference/transapp_read.html#id1609299]
[http://www.oracle.com/technology/documentation/berkeley-db/db/gsg_txn/Java/isolation.html#snapshot_isolation]
Regards,
Andrei -
Hi,
In mssql i am using following things.
I have two database D1 and D2, i am using snapshot isolation (ALTER DATABASE MyDatabase
SET ALLOW_SNAPSHOT_ISOLATION ON) in both database.
Following is the situation.
1) There is one SP sp1 ( it can be in any database d1 or d2), it updates d2 from d1.
2) d2 is used for reading by web, execept above SP sp1
3) d1 gets updation from web in readcommite isolation.
4) both database will be on same instence of mssql.
Q1) wanted to know how to implement the same thing in oracle 11x express edition.
Q2) is there any diffrence between snapshot isolation level of mssql and oracel.
any link would be help full.
yours sincerely>Q1) should i set the option to OFF after the process(ts) is complete
No keep it on.
>Q2) ALLOW_SNAPSHOT_ISOLATION ON , will affect other isolation level's transactions
No it will not affect any other transaction isolation level.
>Q3) is my choice of isolation level for process(ts) is correct or there can be any other solution.
Seems fine, although there are probably many other solutions.
David
David http://blogs.msdn.com/b/dbrowne/ -
CALL TRANSACTION ... UPDATE 'S' and Restartable Update Request
Dear experts,
I have a program that calls a transaction by using the CALL TRANSACTION ... UPDATE 'S' statement. This transaction then performs a database update by using CALL FUNCTION ... IN UPDATE TASK statement. The database update may cause an error due to the primary key conflict.
One behavior that I notice of my program is when the database update raises an error, the corresponding update request in the update table log (SM13) will be flagged as error and non-restartable, eventhough the update module in question is restartable. Why is it like this?
To make my question clearer, I attach my transaction, program and update module below. They are very simple.
Update module:
FUNCTION z_121_15_update_module.
*"*"Update Function Module:
*"*"Local Interface:
*" IMPORTING
*" VALUE(IMP_ZSCARR_CUSTOM) TYPE ZSCARR_CUSTOM
INSERT into zscarr_custom values imp_zscarr_custom.
IF sy-subrc NE 0.
WRITE sy-subrc TO subrc.
MESSAGE subrc TYPE 'A'.
ENDIF.
ENDFUNCTION.
Subroutine in the transaction that calls the update module above:
FORM save.
zscarr_custom-carrname = sy-uzeit.
CALL FUNCTION 'Z_121_15_UPDATE_MODULE' IN UPDATE TASK
EXPORTING
imp_zscarr_custom = zscarr_custom.
COMMIT WORK.
LEAVE TO SCREEN 0.
ENDFORM.
The program that calls the transaction whose the subroutine above:
*& Report Z_121_15_COMPLEX_LUW_19
*& Program that calls a transaction.
*& Called transaction(s): Z_121_15_CLUW_20
REPORT z_121_15_complex_luw_19.
DATA:
it_bdcdata TYPE TABLE OF bdcdata,
wa_bdcdata TYPE bdcdata,
subrc TYPE char10.
wa_bdcdata-program = 'Z_121_15_COMPLEX_LUW_20'.
wa_bdcdata-dynpro = '100'.
wa_bdcdata-dynbegin = 'X'.
APPEND wa_bdcdata TO it_bdcdata.
CLEAR wa_bdcdata.
wa_bdcdata-fnam = 'ZSCARR_CUSTOM-CARRID'.
wa_bdcdata-fval = '01'.
APPEND wa_bdcdata TO it_bdcdata.
CLEAR wa_bdcdata.
wa_bdcdata-fnam = 'BDC_OKCODE'.
wa_bdcdata-fval = 'SAVE'.
APPEND wa_bdcdata TO it_bdcdata.
CALL TRANSACTION 'Z_121_15_CLUW_20' USING it_bdcdata MODE 'E' UPDATE 'A'.
*IF sy-subrc > 0.
WRITE sy-subrc TO subrc.
MESSAGE subrc TYPE 'S'.
*ENDIF.
Thanks in advance.
Regards,
HarisWhat I mean is, for example, when the called update module in the code below issues a type A message,
CALL FUNCTION 'Z_121_15_UPDATE_MODULE' IN UPDATE TASK
EXPORTING
imp_zscarr_custom = zscarr_custom.
COMMIT WORK AND WAIT.
then, in SM13, the corresponding update task will be flagged as non restart-able, eventhough the update module itself is defined as restart-able.
This also happens in the case follows: let the code below is a part of a transaction program that calls an update module
CALL FUNCTION 'Z_121_15_UPDATE_MODULE' IN UPDATE TASK
EXPORTING
imp_zscarr_custom = zscarr_custom.
COMMIT WORK.
and the transaction above is called by a program by using
CALL TRANSACTION 'THE_TRANSACTION_ABOVE' ....... UPDATE 'S'.
Am I correct? This is my conclusion so far. -
Complex Oracle Streams issue - Update conflicts
This is for Oracle streams replication on 11g r2.
I am facing update conflicts in a table. The conflict arise due to technical and business logic issue. The business logic will pass through the replication/apply process successfully but we want to arrest and resolve it before replication for our requirements. These are typically a bit complex cases and we are exploring the possibility of having both DML handlers and Error handlers. The DML handlers will take care of business logic conflicts and Error handler for technical issues before pushing it to Error queue by Streams. Based on our understanding and verification, we found a limitation to configure both procedure DML handler and Error handler together for the same table operation.
Statement handlers can not be used for our conflict scenarios.
Following are my questions:
1. Have anyone implemented or faced such a scenario in their real time application? If yes, can you please share some insights or inputs?
2. Is there a custom way to handle this complex problem of configuring both DML and Error handler?
3. Is there any alternative possible way to resolve this situation at Oracle streams environment with other handlers?Dear All
I too have a similar requirement. Could anyone help with one?
We can handle the error-ing transactions via Error Handler procedures.
But we can not configure the DML handler procedure for transactions that are successfully replicated. STreams does not allow us to configure a handler for this. Is there any other handler / procedures / hooks in streams where we can implement the desired functionality - which includes changing the values in the LCR before invoking lcr.execute() and we should be able to discard the LCR also if required.
Regards
Velmurugan
Edited by: 982387 on Jan 16, 2013 11:25 PM
Edited by: 982387 on Jan 16, 2013 11:27 PM -
Segmentation fault when using snapshot isolation with Berkeley DB 6.1.19 and 5.1.29
Hello,
I have been experimenting with snapshot isolation with Berkeley DB, but I find that it frequently triggers a segmentation fault when write transactions are in progress. The following test program reliably demonstrates the problem in Linux using either 5.1.29 or 6.1.19.
https://anl.app.box.com/s/3qq2yiij2676cg3vkgik
Compilation instructions are at the top of the file. The test program creates a temporary directory in /tmp, opens a new environment with the DB_MULTIVERSION flag, and spawns 8 threads. Each thread performs 100 transactional put operations using DB_TXN_SNAPSHOT. The stack trace when the program crashes generally looks like this:
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff7483700 (LWP 11871)]
0x00007ffff795e190 in __memp_fput ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
(gdb) where
#0 0x00007ffff795e190 in __memp_fput ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#1 0x00007ffff7883c30 in __bam_get_root ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#2 0x00007ffff7883dca in __bam_search ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#3 0x00007ffff7870246 in ?? () from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#4 0x00007ffff787468f in ?? () from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#5 0x00007ffff79099f4 in __dbc_iput ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#6 0x00007ffff7906c10 in __db_put ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#7 0x00007ffff79191eb in __db_put_pp ()
from /usr/lib/x86_64-linux-gnu/libdb-5.1.so
#8 0x0000000000400f14 in thread_fn (foo=0x0)
at ../tests/transactional-osd/bdb-snapshot-write.c:154
#9 0x00007ffff7bc4182 in start_thread (arg=0x7ffff7483700)
at pthread_create.c:312
#10 0x00007ffff757f38d in clone ()
at ../sysdeps/unix/sysv/linux/x86_64/clone.S:111
I understand that this test program, with 8 concurrent (and deliberately conflicting) writers, is not an ideal use case for snapshot isolation, but this can be triggered in other scenarios as well.
You can disable snapshot isolation by toggling the value of the USE_SNAP #define near the top of the source, and the test program then runs fine without it.
Can someone help me to identify the problem?
many thanks,
-PhilHi Phil,
We have taken a look at this in more detail and there was a bug in the code. We have fixed the bug. We will roll it into our next 6.1 release that we do. If you would like an early patch that will go on top of 6.1.19, please email me at [email protected], reference this forum post and I can get a patch sent out to you. It will be a .diff file that apply on the source code and then rebuild the library. Once again thanks for finding the issue, and providing a great test program which tremendously helped in getting this resolved.
thanks
mike -
Snapshot isolation level usage
Dear All,
There are some transaction tables in which more than one user add and update records (only).
what ever they add and update in transaction tables, based on that entry they add a record in Table A1
, Table A1 has two cols one keeps the table name of transaction table and other col keeps the pk(primarykey) of transaction tables.
So Table A1 always gets only inserts,
Table A1 gets entry only for transaction tables , and only when transaction table gets entry .
At the same time there is a process (ts) which reads Table A1 on time basis, picks up all records
form Table A1 and reads data from transaction tables on the basis of PK stored in it . there it after inserts all the read records into a
new temp table.
and at the end of transaction it deletes records from Table A1.
after some time it again picks up new records from Table A1 and repeats the process.
For process (ts) . i want to use ALLOW_SNAPSHOT_ISOLATION
so that user can keep on entering records.
Q1) The ALLOW_SNAPSHOT_ISOLATION
database option must be set to ON
before one can start a transaction that uses the SNAPSHOT isolation level. I wanted to know should i set the option to OFF after the process(ts) is complete, and switch
it on again on the database when process(ts) starts again.
that is, keeping it on all the time will affect the database in any case?
Q2) ALLOW_SNAPSHOT_ISOLATION ON , will affect other isolation level's transactions or only to snapshot isolation levels transactions. that is, i have old
stored proc and front end applications like web or window on .net which are using default isolation levels.
Q3) is my choice of isolation level for process(ts) is correct or there can be any other solution.
Note: "the information is quite less but i wont be able to give full information."
yours sincerely>Q1) should i set the option to OFF after the process(ts) is complete
No keep it on.
>Q2) ALLOW_SNAPSHOT_ISOLATION ON , will affect other isolation level's transactions
No it will not affect any other transaction isolation level.
>Q3) is my choice of isolation level for process(ts) is correct or there can be any other solution.
Seems fine, although there are probably many other solutions.
David
David http://blogs.msdn.com/b/dbrowne/ -
Berkeley DB's Snapshot Isolation
After read the reference document, I think snapshot isolation means that a write operation will take a read lock in the data page under a transation. After that another transaction with read operation can read the page.But I code it like this:
step1:txn1 update the page but not commited
step2:txn2 read the page
step3:commit txn1
step4:commit txn2
The program is stop in step2 and wait forever.Then I change step1 for read, It can excete normally.That's seems like the snapshot isolation is still take a wirte lock int the page.I feel confuss about how snapshot isolation works.
If someone can give me an example program , or tell me how it works , I will thank you quit a lot.Hi,mike,thanks for you answer.I read the document again and again today.According to the suggestion,we usually use snapshot in a read-only transaction and another update transation to write. So I recode my program with a read-only transaction and a update transaction.But it is also blocked like before.I feel so confuse. I put my program here and wish you can help me with that. thanks for your time.
#include"db_cxx.h"
#include<iostream>
#include<cstring>
int main()
u_int32_t env_flags = DB_CREATE |
DB_INIT_LOCK |
DB_INIT_LOG |
DB_INIT_MPOOL |
DB_INIT_TXN;
const char* home = "envHome";
u_int32_t db_flags = DB_CREATE | DB_AUTO_COMMIT;
const char* fileName = "envtest.db";
Db* dbp = NULL;
DbEnv myEnv(0);
try{
myEnv.open(home,env_flags,0);
myEnv.set_flags(DB_MULTIVERSION,1);
dbp = new Db(&myEnv,0);
dbp->open(
NULL, //Txn pointer
fileName, //File name
NULL, //Logic db name
DB_BTREE, //Database type
db_flags, //Open flags
0 //file mode
}catch(DbException &e){
std::cerr<<"Error when opening database and Environment:"
<<fileName<<","<<home<<std::endl;
std::cerr<<e.what()<<std::endl;
//put data normally
char *key1 = "luffy";
char *data1 = "op";
char *key2= "usopp";
char *data2 = "brave";
Dbt pkey1(key1,strlen(key1)+1);
Dbt pdata1(data1,strlen(data1)+1);
Dbt pkey2(key2,strlen(key2)+1);
Dbt pdata2(data2,strlen(data2)+1);
dbp->put(NULL,&pkey1,&pdata1,0);
dbp->put(NULL,&pkey2,&pdata2,0);
//using txn cursor to read and another cursor to modify before commit
try{
DbTxn *txn1 = NULL;
myEnv.txn_begin(NULL,&txn1,DB_SNAPSHOT);
Dbc *cursorp = NULL;
dbp->cursor(txn1,&cursorp,0);
Dbt tempData1,tempKey2,tempData2;
tempData2.set_flags(DB_DBT_MALLOC);
cursorp->get(&pkey1,&tempData1,DB_SET);
cursorp->get(&tempKey2,&tempData2,DB_NEXT);
//cout just to see if it is right
std::cout<<(char*)pkey1.get_data()<<" : "<<(char*)tempData1.get_data()<<std::endl
<<(char*)tempKey2.get_data()<<" : "<<(char*)tempData2.get_data()<<std::endl;
//txn2 to modify
DbTxn *txn2 = NULL;
myEnv.txn_begin(NULL,&txn2,0);
Dbc *temcur = NULL;
dbp->cursor(txn2,&temcur,0);
temcur->put(&pkey1,&pdata2,DB_KEYFIRST); //the program will stop here and wait forever. if the snapshop isolation made a copy before , why still block here?
//without this line,there won't deadlock.that means page was put a write lock before
//commit the txn
txn1->commit(0);
txn2->commit(0);
}catch(DbException &e){
std::cerr<<"Error when use a txn"<<std::endl;
try{
dbp->close(0); //dbp should close before environment
myEnv.close(0);
}catch(DbException &e){
std::cerr<<"Error when closing database and environment:"
<<fileName<<","<<home<<std::endl;
std::cerr<<e.what()<<std::endl;
return 0; -
Unable to upgrade due to a conflict [SOLVED]
Greetings you all.
I've been tried to upgrade my system and I've been unable to do it due to a conflict between xf86-video-openchrome and unichrome-dri.
This is the pacman output:
[root@Viper /]# pacman -Syu
:: Synchronizing package databases...
core is up to date
extra is up to date
community is up to date
multilib is up to date
:: Starting full system upgrade...
:: Replace farsight2 with extra/farstream? [Y/n] y
:: Replace gnupg2 with core/gnupg? [Y/n] y
:: Replace procps with core/procps-ng? [Y/n] y
:: Replace seahorse-plugins with community/seahorse-nautilus? [Y/n] y
:: Replace sqlite3 with extra/sqlite? [Y/n] y
:: Replace telepathy-farsight with extra/telepathy-farstream? [Y/n] y
:: Replace xfce-utils with extra/xfce4-appfinder? [Y/n] y
:: Replace xfce-utils with extra/xfce4-session? [Y/n] y
resolving dependencies...
warning: dependency cycle detected:
warning: util-linux will be installed before its udev dependency
looking for inter-conflicts...
:: xf86-video-openchrome and unichrome-dri are in conflict. Remove unichrome-dri? [y/N] y
error: failed to prepare transaction (could not satisfy dependencies)
:: lib32-unichrome-dri: requires lib32-libgl=7.11.2
Can anybody tel me how do I solve this?
I already have libgl installed...
[root@Viper /]# pacman -S libgl
resolving dependencies...
looking for inter-conflicts...
error: failed to prepare transaction (could not satisfy dependencies)
:: nouveau-dri: requires libgl=7.11.2
:: unichrome-dri: requires libgl=7.11.2
[root@Viper /]# pacman -Q libgl
libgl 7.11.2-1
If trying to uninstall unichrome-dri, it returns:
[root@Viper /]# pacman -R unichrome-dri
checking dependencies...
error: failed to prepare transaction (could not satisfy dependencies)
:: xf86-video-openchrome: requires unichrome-dri
And by the way, is it safe do replace all those items that appeared before?
Thank you all.
Last edited by JMRamos (2012-05-31 16:01:12)Thanks for your quick response, but only today I had a chance of look into this again...
I use an on board chipset from VIA Technologies, and the only way I figured to get that old gadget (VIA Technologies, Inc. P4M890) working is by using Openchrome. Mesa simply doesn't work and vesa has some issues.
So I followed your advice, by removing xf86-video-openchrome, updating and installing it again.
Everything is working now.
Thanks a lot. -
Turning On Snapshot Isolation Gotchas
Hello Experts,
We have been experiencing high number of Deadlocks while using MERGE statement and turning on Snapshot Isolation perfectly solves our problem and our throughput and concurrency didn't get affected at all.
We did load testing and monitored TempDB VersionStore size and it was nothing significant and we have 64 Gig Memory allocated in Prod Server. Our team did the reading and research primarily from these online sources.
My Question is "Is there any gotchas in turing on SnapShot Isolation you won't see right away?". I want learn from experiences before we venture into turning it on in our production Environment?. I saw some folks experienced 60 Gig Version Store
because there was 3 month old active transaction.
What kind of preventive and maintenance scripts would be useful to monitor the system and take corrective action?.
I have few scripts to monitor tempdb version store size, and peformon Transaction Counters. Is there any other better scripts/tools available?.
Kimberly Tripp Video on Isolation Levels :
http://download.microsoft.com/download/6/7/9/679B8E59-A014-4D88-9449-701493F2F9FD/HDI-ITPro-TechNet-mp4video-MCM_11_SnapshotIsolationLecture(4).m4v
Kendra Little on SnapShot Isolatioin :
http://www.brentozar.com/archive/2013/01/implementing-snapshot-or-read-committed-snapshot-isolation-in-sql-server-a-guide/
Microsoft Link: https://msdn.microsoft.com/en-us/library/ms188277(v=sql.105).aspx
https://msdn.microsoft.com/en-us/library/bb522682.aspx
SQL Team Link : http://www.sqlteam.com/article/transaction-isolation-and-the-new-snapshot-isolation-level
Idera Short article on TempDB : http://sqlmag.com/site-files/sqlmag.com/files/uploads/2014/01/IderaWP_Demystifyingtempdb.pdf
Jim Gray Example by Craig Freedman : http://blogs.msdn.com/b/craigfr/archive/2007/05/16/serializable-vs-snapshot-isolation-level.aspx
Thanks in advance.
~I90Runner
I90RunnerIt is unclear what isolation level have you enabled RCSI or SI?
Downsides:
Excessive tempdb usage due to version store activity. Think about session that deletes 1M rows. All those rows must be copied to version store regardless of session transaction isolation level and/or if there are other sessions
that running in optimistic isolation levels at the moment when deletion started.
Extra fragmentation – SQL Server adds 14-byte version tag (version store pointer) to the rows in the data files when they are modified. This tag stayed until index is rebuild
Development challenges – again, error 3960 with snapshot isolation level. Another example in both isolation levels – trigger or code based referential integrity. You can always solve it by adding with (READCOMMITTED) hint
if needed.
While switching to RCSI could be good emergency technique to remove blocking between readers and writers (if you can live with overhead AND readers are using read committed), I would suggest to find root cause of the blocking.
Confirm that you have locking issues – check if there are shared lock waits in wait stats, that there is no lock escalations that block readers, check that queries are optimized, etc.
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
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