Here is our environment:
.Net version: 4.5
Database: Oracle 12.1.0.2 (odp.net)
We are using LLBL "Adapter" but I don't think that has anything to do with the issue
LLBLGen Pro version: 4.1
Llbl Gen Pro Runtime: 4.1.13.1213
When we do an Insert(always into different tables which we are using for the short period and then removing) we use the following code:
int numRecords = strings.Count();
var insertCmd = "insert into " + tableName + " (StringField) values (:StringField)";
var oracleCommand = new OracleCommand();
oracleCommand.CommandText = insertCmd;
oracleCommand.CommandType = CommandType.Text;
oracleCommand.BindByName = true;
oracleCommand.ArrayBindCount = numRecords;
oracleCommand.Parameters.Add(":StringField", OracleDbType.NVarchar2, strings.ToArray(), ParameterDirection.Input);
// this is an LLBL adapter. Like I said, I think the issue is below the LLBL layer.
this.adapter.ExecuteActionQuery(new ActionQuery(oracleCommand));
When the database is getting hit hard with multiple of these inserts in parallel, we get the following error and the insert call never returns from the database.
WG_6.Index_586.TVD: An exception was caught during the execution of an action query: ORA-24381: error(s) in array DML
ORA-12592: TNS:bad packet
ORA-12592: TNS:bad packet
ORA-12592: TNS:bad packet
ORA-12592: TNS:bad packet
ORA-03111: break received on communication channel
ORA-03111: break received on communication channel
ORA-03111: break received on communication channel
On the database, using Toad's session browser, I can see that the "Current Statement" is correct.
insert into schemaX.tableY(StringField) values(:Stringfield)
Under the Waits tab in Toad, there is the following message:
“Waiting for SQL*Net more data from client - waited X hundred seconds, so far” and the X keeps incrementing until we hit our database timeout.
We tried with batches of 1 million and this gave us the best performance for our scenario. However, this hanging issue arose. I then decrease the ArrayBindCount to 500K, 100K, 50K, 10K and then 5K. Only when I used 5K did it stop happening.
A couple of notes:
This happens more frequently when the database is on a different physical machine than the client. When using a local VM, it rarely happens. The network that we are using is generally very reliable with no other noted issues.
From the error message(ORA-12592: TNS:bad packet), it seems that the issue might be on the client and perhaps related to code in the "Oracle.DataAccess.Client"(ODAC) dll.
My next steps for troubleshooting are to use Reflector to debug the call from the ODAC code and also to get more reliable client side tracing while forcing this error to occur.
I had the same situation when trying to insert into an Oracle table using the ArrayBinding.
Using a small number for oracleCommand.ArrayBindCount seemed to improve the frequency of the errors (same like yours) but not completely.
The solution was to use the Managed data access. I suggest you get the latest ODP.NET, add a reference to ManagedDataAccess and change to:
using Oracle.ManagedDataAccess.Client;
using Oracle.ManagedDataAccess.Types;
This fixed problem in my case and with no need to change anything in the code.
Related
We are trying to track down the cause of a performance problem.
We have a table with a single row that contains a primary key and a counter. Within a transaction we read the value of the counter, increment the value by one and save the new value.
The read and update is done using Entity Framework, we use a serializable transaction scope, we need to ensure that a counter value is read once only.
Most of the time this takes 0.1 seconds, then sometimes it takes over 1 second. We have not been able to find any pattern as to why this happen.
Has anyone else experienced variable performance when using transaction scope? Would it help to drop using transaction scope and set the transaction directly on the connection?
I remember commenting on this question a long time ago, but recently some developers in my shop have started using TransactionScope, and have also run into performance issues. While trying to search for some information, this came up pretty high in the Google Search results.
The issue we ran into was that, apparently chaining commands (INSERTs, etc.) with BeginChain does not work when using a TransactionScope (at least on the version we are running, Client v9.7.4.4 connecting to DB2 z/OS v 10).
I thought that I would leave a workaround for the issue we ran into (slow performance when running lots [1k+] of INSERTs under TransactionScope, but ran fine when the scope was removed and chaining was allowed). I'm not really sure if it would help the original question directly, but there are some options if you look in the IBM.Data.DB2.dll classes that allow you to update rows using a DB2DataAdapter and an underlying DataTable.
Here's some example code in VB.NET:
Private Sub InsertByBulk(tableName As String, insertCollection As List(Of Object))
Dim curTimestamp = Date.Now
Using scope = New TransactionScope
'Something that opens a connection to DB2, may vary
Using conn = GetDB2Connection()
'Dumb query to get DataTable from the ResultSet
Dim sql = String.Format("SELECT * FROM {0} WHERE 1=0", tableName)
Using adapter = New DB2DataAdapter(sql, conn)
Using table As New DataTable
adapter.FillSchema(table, SchemaType.Source)
For Each item In insertCollection
Dim row = table.NewRow()
row("ID") = item.Id
row("CHAR_FIELD") = item.CharField
row("QUANTITY") = item.Quantity
row("UPDATE_TIMESTAMP") = curTimestamp
table.Rows.Add(row)
Next
Using bc = New DB2BulkCopy(conn)
bc.DestinationTableName = tableName
bc.WriteToServer(table)
End Using 'BulkCopy
End Using 'DataTable
End Using 'DataAdapter
End Using 'Connection
scope.Complete()
End Using
End Sub
We have now solved this problem.
The root of the problem was that the DB2 provider does not support transaction promotion. This results in Transaction Scope using MSDTC distributed transactions for everything.
We replaced the use of Transaction Scope with transactions set on the database connection.
Composite services that included the code in the question were then reduced from 3 seconds to 0.3 seconds.
We have our application calling to two Oracle databases using two connections (which are kept open through out the application). For certain functionality, we use distributed transactions. We have Enlist=false in the connection string and manually enlist the connection to the transaction.
The problem comes with a scenario where, we update the same record very frequently within a distributed transaction, on which we see a delay to see the commited data in the previous run.
ex.
using (OracleConnection connection1 = new OracleConnection())
{
using(OracleConnection connection2 = new OracleConnection())
{
connection1.ConnectionString = connection1String;
connection1.Open();
connection2.ConnectionString = connection2String;
connection2.Open();
//for 100 times, do an update
{
.. check the previously updated value
connection1.EnlistTransaction(currentTransaction);
connection2.EnlistTransaction(currentTransaction);
.. do an update using connection1
.. do some updates with connection2
}
}
}
as in the above code fragment, we do update and check the previously updated value in the next iteration. The issues comes up when we run this for a single record frequently, on which we don't see the committed update in the last iteration in the next iteration even though it was committed in the previous iteration. But when this happens this update is visible in other applications in a very very small delay, and even within our code it's visible if we were to debug and run the line again.
It's almost like delay in the commit even though previous commit returned from the code.
Any one has any ideas ?
It turned out that I there's no way to control this behavior through ODAC. So the only viable solution was to implement a retry behavior in our code, since this occurs very rarely and when it happens, delay 10 seconds and retry the same.
Additional details on things I that I found on this can be found here.
I get the following error under a certain scenario
When a different thread is populating a lot of users via the bulk upload operation and I was trying to view the list of all users on a different web page. The list query, throws the following timeout error. Is there a way to set this timeout so that I can avoid this timeout error.
Env: h2 (latest), Hibernate 3.3.x
Caused by: org.h2.jdbc.JdbcSQLException: Timeout trying to lock table "USER"; SQL statement:
[50200-144]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:327)
at org.h2.message.DbException.get(DbException.java:167)
at org.h2.message.DbException.get(DbException.java:144)
at org.h2.table.RegularTable.doLock(RegularTable.java:482)
at org.h2.table.RegularTable.lock(RegularTable.java:416)
at org.h2.table.TableFilter.lock(TableFilter.java:139)
at org.h2.command.dml.Select.queryWithoutCache(Select.java:571)
at org.h2.command.dml.Query.query(Query.java:257)
at org.h2.command.dml.Query.query(Query.java:227)
at org.h2.command.CommandContainer.query(CommandContainer.java:78)
at org.h2.command.Command.executeQuery(Command.java:132)
at org.h2.server.TcpServerThread.process(TcpServerThread.java:278)
at org.h2.server.TcpServerThread.run(TcpServerThread.java:137)
at java.lang.Thread.run(Thread.java:619)
at org.h2.engine.SessionRemote.done(SessionRemote.java:543)
at org.h2.command.CommandRemote.executeQuery(CommandRemote.java:152)
at org.h2.jdbc.JdbcPreparedStatement.executeQuery(JdbcPreparedStatement.java:96)
at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:342)
at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
at org.hibernate.loader.Loader.getResultSet(Loader.java:1808)
at org.hibernate.loader.Loader.doQuery(Loader.java:697)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259)
at org.hibernate.loader.Loader.doList(Loader.java:2228)
... 125 more
Yes, you can change the lock timeout. The default is relatively low: 1 second (1000 ms).
In many cases the problem is that another connection has locked the table, and using multi-version concurrency also solves the problem (append ;MVCC=true to the database URL).
EDIT: MVCC=true param is no longer supported, because since h2 1.4.200 it's always true for a MVStore engine, which is a default engine.
I faced quite the same problem and using the parameter "MVCC=true", it solved it. You can find more explanations about this parameter in the H2 documentation here : http://www.h2database.com/html/advanced.html#mvcc
I'd like to suggest that if you are getting this error, then perhaps you should not be using a transaction on your bulk database operation. Consider instead doing a transaction on each individual update: does it make sense to think of an entire bulk import as a transaction? Probably not. If it does, then yes, MVCC=true or a bigger lock timeout is a reasonable solution.
However, I think for most cases, you are seeing this error because you are trying to perform a very long transaction - in other words you are not aware that you are performing a really long transaction. This was certainly the case for myself and I simply took more care on how I was writing records (either using no transactions or using smaller transactions) and the lock timeout issue was resolved.
For those having this issue with integration tests (i.e. server is accessing the h2 db and an integration test is accessing the db before calling the server, to prepare the test), adding a 'commit' to the script executed before the test makes sure that the data are in the database before calling the server (without MVCC=true - which I find is a bit 'weird' if it is not enabled by default).
I had MVCC=true in my connection string but still was getting error above. I had added ;DEFAULT_LOCK_TIMEOUT=10000;LOCK_MODE=0 and problem was solved
I got this issue with the PlayFramework
JPAQueryException occured : Error while executing query from
models.Page where name = ?: Timeout trying to lock table "PAGE"
It ended being an infinite loop of sorts because I had a
#Before
without an unless which caused the function to repeatedly call itself
#Before(unless="getUser")
Working with DBUnit, H2 and Hibernate - same error, MVCC=true helped, but I would still get the error for any tests following deletion of data. What fixed these cases was wrapping the actual deletion code inside a transaction:
Transaction tx = session.beginTransaction();
...delete stuff
tx.commit();
From a 2020 user, see reference
Basically, the reference says:
Sets the lock timeout (in milliseconds) for the current session. The default value for this setting is 1000 (one second).
This command does not commit a transaction, and rollback does not affect it. This setting can be appended to the database URL: jdbc:h2:./test;LOCK_TIMEOUT=10000
I've got a really odd issue that I've not had any success googling for.
It started happening with no changes to the DB, connection settings, code etc.
Problem is, when accessing a servlet, one of the EJB's is doing a direct SQL call, very simple
"select \n" +
" value, \n" +
" other_value \n" +
" from \n" +
" some_table \n" +
" where some_condition = ? "
That's obviously not the direct SQL, but pretty close. For some reason, this started returning an error stating "ORA-00942: table or view does not exist".
The table exists, and the kicker is if I hook in a debugger, change a space or something minor (not changing the query itself) in the query, and hot-deploy the change, it works fine. This isn't the first time I've run across this. It only seems to happen in dev environments (haven't seen it in q/a, sandbox, or production yet), is not always replicable, and driving me seriously insane.
By not always replicable I mean that occasionally a clean build & redeploy will sometimes fix the problem, but not always. It's not always the same table (although if the error occurs it continues with the same query).
Just throwing a feeler out there to see if anybody has run into issues like this before, and what they may have discovered to fix it.
Sounds like maybe one connection in your JDBC pool has a problem, which could explain the intermittent nature and that redeploy only sometimes fixes it, as you could end up still using the same connection afterwards. You could try resetting the connection pool instead of redeploying, perhaps. (java weblogic.Admin -url t3://<server_url> RESET_POOL <pool_name>, I think)
You've said there's only one schema, but does that mean only one schema exists or that all the tables are under one schema? Is it possible that you're doing an ALTER SESSION SET CURRENT_SCHEMA somewhere, and when whichever connection that's issued against is returned to the pool and then randomly used for the query later it can't see anything in the main schema any more? That could happen in a package or trigger as well as from the Java side, and could be a 'temporary' change that doesn't get reverted after an exception. Sounds like something that might only exist in a dev environment, too...
We have a lagacy VB6 app that uses an ODBC connection to a Oracle 10g DB. We are upgrading to a 11g drivers on our SOE and parts of the app have issues. Works fine with a 9.2 driver.
Oracle Client 10g/11g does not like lower-case calls. This is evident in the fact that the calls that succeed are in upper case and the calls that failed are in lower case. Further tests showed that lines of code such as:
Set Qry = grdoEnterprise.CreateQuery("", " { CALL ep_admin_revoke_role( ?,?,?,? ) } ")
failed... but succeeded when changed to
Set Qry = grdoEnterprise.CreateQuery("", " { CALL EP_ADMIN_REVOKE_ROLE( ?,?,?,? ) } ")
The error itself isn't thrown until the query is executed. However, while debugging, failure can be detected at the CreateQuery() stage because the resulting rdoQuery object has 0 parameters (whereas it should have more than 0--in this case, 4).
Has anyone encounter this problem with VB6 and Oracle 10g/11g ODBC drivers?
Yes, Oracle is way too picky. Your solution to change the stored procedure name to upper case is one hundred percent correct.