I have a Comments db table
var c = new comment
{
name = message,
userID = userId
};
this.commentDataContext.Comments.InsertOnSubmit(c);
this.commentDataContext.SubmitChanges();
this.logger.WriteInfo($"Message: {c.name}");
this.logger.WriteInfo($"CommentId: {c.id}");
Within my log files I do receive an CommentId
2019-11-04 11:06:28,042 [79] INFO Root [(null)] - CommentId: 271609
However when I do a query on the db table it returns nothing.
Is it rolling back? I have looked at the event viewer but see no errors. As this is on a live server, I hope to not go down the route of turning on tracking as its constantly being hit, so will be like trying to find a needle in a hay stack. Is there another way I can work out why it thinks it has inserted but then roll-backed the change?
Related
I am trying to insert data in one table using Ef core 5 with repository pattern and Unit of work.
Code Sample :
var stateData = new State
{
StateId = state.StateId,
Action = state.Action,
Event = state.Event,
ExecutedOn = DateTime.Now
};
_unitOfWork.GetRepository<State>().Add(stateData);
var result = _unitOfWork.Commit();
GetRepository method used to get respective repo:
{
return (IRepository<TEntity>)GetOrAddRepository(typeof(TEntity), new
Repository<TEntity>(Context));
}
Commit Method :
{
return Context.SaveChanges();
}
I am trying to insert data in state table which has Id as primary and identity column. Rest other columns are StateId,Action,Event and ExecutedOn(datatype : datetime2).
Application is running on multiple nodes. So there will be multiple insert request at a same time from multiple node but different data.
I am getting DbUpdateConcurrencyException frequently while inserting the records of states in DB. Sometimes it works but most of time I get DbUpdateConcurrencyException with message "Database operation expected to affect 1 row(s) but actually affected 0 row(s). Data may have been modified or deleted since entities were loaded. See http://go.microsoft.com/fwlink/?LinkId=527962 for information on understanding and handling optimistic concurrency exceptions".
There is no update operation but still I am getting concurrency exception.
I have tried all others solutions on similar questions but no luck.
I am attempting to use clairvoyant's db-cleanup dag to clear metadata in our xcom table, but when I run it, I receive the following warning, printed thousands of times before I manually stop the job in order to not take down our mysql instance:
SAWarning: Loading context for <BaseXCom at 0x7f26f789b370> has changed within a load/refresh handler, suggesting a row refresh operation took place. If this event handler is expected to be emitting row refresh operations within an existing load or refresh operation, set restore_load_context=True when establishing the listener to ensure the context remains unchanged when the event handler completes.
The other cleanup tasks work fine, but it is the xcom table in particular I am having trouble with. We have hundreds/thousands of active dags and so the xcom table is constantly being written to nearly every second or two. I think that is what is causing this error, the fact that the data is continually changing while it is being queried.
I have been unable to find the cause of this or any examples of how this can be resolved. I tried adding a "restore_load_context":True line as per SQLAlchemy docs but it did not work.
Here are the snippets I attempted to add to the database object and the cleanup task:
{
"airflow_db_model": XCom,
"age_check_column": XCom.execution_date,
"keep_last": False,
"keep_last_filters": None,
"keep_last_group_by": None,
"restore_load_context":True
},
....
def cleanup_function(**context):
logging.info("Retrieving max_execution_date from XCom")
max_date = context["ti"].xcom_pull(
task_ids=print_configuration.task_id, key="max_date"
)
max_date = dateutil.parser.parse(max_date) # stored as iso8601 str in xcom
airflow_db_model = context["params"].get("airflow_db_model")
state = context["params"].get("state")
age_check_column = context["params"].get("age_check_column")
keep_last = context["params"].get("keep_last")
keep_last_filters = context["params"].get("keep_last_filters")
keep_last_group_by = context["params"].get("keep_last_group_by")
restore_load_context = context["params"].get("restore_load_context")
In order to not paste too much code here, I am using the same code in the db-cleanup dag. Has anyone encountered this and found a way to resolve?
I am very inexperienced with sqlalchemy and am entirely unsure where else to place this code or how to go about it.
I have 2 instances of a VB.NET application each running on their own dedicated servers. The said application runs a While true loop with a 5s sleep on IDLE (IDLE is when the Table doesn't have any ProcessQuery to be treated). On each iteration, the application questions a table in the SQL Database to know if there is anything it could process.
The problem is that i sometimes encounter the problem where both of the instances are "taking" the same ProcessQuery.
I'm using EntityFramework6. I have looked into EntityState but i don't think it does exactly what i'm trying to accomplish.
I was wondering what would be my solution to have perfect parallel instances. It's not impossible at some point i have 12 instances running on 12 machines.
Thanks!
Dim conn As New Info_IndusEntities()
Dim DemandeWilma As WilmaDemandes = conn.WilmaDemandes.Where(Function(x) x.Site = 'LONDON' AndAlso x.Statut = 'toProcess').OrderBy(Function(x) x.RequestDate).FirstOrDefault
If Not IsNothing(DemandeWilma) Then
DemandeWilma.Statut = Statuts.EnTraitement.ToString
DemandeWilma.ServerName = Environment.MachineName
DemandeWilma.ProcessDate = DateTime.Now
conn.SaveChanges()
Return DemandeWilma
end if
UPDATE (21/06/19)
I found an article that I find interesting.
I started by adding a column to my Table :
UPDATED (21/06/19)
I then refreshed my model and changed the Concurrency Check property of RowVersion column in my ORM :
When I tested the update, here's the log of EF6 :
UPDATE [dbo].[WilmaDemandes] SET [Statut] = #0, [ServerName] = #1,
[DateDebut] = #2 WHERE (([ID] = #3) AND ([RowVersion] = #4)) SELECT
[RowVersion] FROM [dbo].[WilmaDemandes] WHERE ##ROWCOUNT > 0 AND [ID]
= #3
-- #0: 'EnTraitement' (Type = String, Size = 20)
-- #1: 'TRB5995' (Type = String, Size = 20)
-- #2: '2019-06-25 7:31:01 AM' (Type = DateTime2)
-- #3: '124373' (Type = Int32)
-- #4: 'System.Byte[]' (Type = Binary, Size = 8)
-- Executing at 2019-06-25 7:31:24 AM -04:00
-- Completed in 95 ms with result: SqlDataReader
Closed connection at 2019-06-25 7:31:24 AM -04:00
Exception thrown:
'System.Data.Entity.Infrastructure.DbUpdateConcurrencyException' in
EntityFramework.dll
UPDATED (25/06/19)
The problems, as explained in this post, starts when you are using DB-First instead of Code-First. Your property will get overwritten silently as soon as you update the model. Some people back then coded a console app workaround that they run on pre-build. I'm not sure i'm quite ready to take this solution as final solution.
Interesting tutorial on how to test optimistic concurrency and ways to resolve such an exception.
Add an "owner" column to your queue table
Your application updates one record (TOP 1) and sets the owner value to their identifier (WHERE Owner IS NULL)
Now your application goes back and reads their owned rows and processes them
It's a simple pattern and it works great. If any processes happen to take ownership 'simultaneously', only one will actually get the reservation.
I'm not very good at LINQ so here's a brute force method, multiline for clarity:
// First try reserving a row
conn.Database.ExecuteSqlCommand(
"WITH UpdateTop1 AS
(SELECT TOP 1 * FROM WilmaDemandes
WHERE Owner IS NULL
AND Site = 'LONDON'
ORDER BY RequestDate)
UPDATE UpdateTop1 SET Owner='ThisApplication'"
);
// See if we got one
Dim DemandeWilma As WilmaDemandes =
conn.WilmaDemandes.
Where(x => x.Owner=='ThisApplication').FirstOrDefault
// If we got a row, process it. Otherwise Idle and repeat
There's also no reason that you must reserve one row. You could reserve all the free rows and work your way through them. Meanwhile other processes will pick up any subsequently arriving rows
Personally I would refactor your status column and make it NULL for new records ready to be processed, otherwise it's the worker ID that has reserved it.
It also helps to add things like timestamp columns to record when the row was reserved etc.
I'm using hsqldb to create cached tables and indexed tables.
The data being stored has pretty high frequency so I need to use a connection pool.
Also because there is a lot of data I do not call checkpoint on every commit, but rather expect the data to be flushed after 50,000 rows are inserted.
So the thing is that I can see the .data file is growing but when I connect with hsqldb client I don't see the tables and the data.
So I had 2 simple tests, one inserted single row and one inserted 60,000 rows to new table. In both cases I couldn't see the result in any hsqldb client.
(Note that I use shutdown=true)
So when I add checkpoint after each commit, it solve the problem.
Also if specify in the connection string to use log, it solves the problem (I don't want the log in production though). Also not using pooled connection solved the problem and last is using pooled data source and explicitly close it before shutdown.
So I guess that some connections in the connection pool are not being closed, preventing from the db to somehow commit the changes and make them available for the client. But then, why couldn't I see the result even with 60,000 rows?
I also would expect the pool to be closed automatically...
What am I doing wrong? What is happening behind the scene?
The code to get the data source looks like this:
Class.forName("org.hsqldb.jdbcDriver");
String url = "jdbc:hsqldb:" + m_dbRoot + dbName + "/db" + ";hsqldb.log_data=false;shutdown=true;hsqldb.nio_data_file=false";
ConnectionFactory connectionFactory = new DriverManagerConnectionFactory(url, user, password);
GenericObjectPool connectionPool = new GenericObjectPool();
KeyedObjectPoolFactory stmtPool = new GenericKeyedObjectPoolFactory(null);
new PoolableConnectionFactory(connectionFactory, connectionPool, stmtPool, null, false, true);
DataSource ds = new PoolingDataSource(connectionPool);
And I'm using this Pooled data source to create table:
Connection c = m_dataSource.getConnection();
Statement st = c.createStatement();
String script = String.format("CREATE CACHED TABLE IF NOT EXISTS %s (id %s NOT NULL, entity %s NOT NULL, PRIMARY KEY (id));", m_tableName, m_idGenerator.getIdType(), TABLE_ENTITY_TYPE);
st.execute(script);
c.close;
st.close();
And insert rows:
Connection c = m_dataSource.getConnection();
c.setAutoCommit(false);
Statement stmt = c.prepareStatement(m_sqlInsert);
stmt.setObject(1, id);
stmt.setBinaryStream(2, Serializer.Helper.serialize(m_serializer, entity));
stmt.executeUpdate();
stmt.close();
stmt = null;
c.commit();
c.close();
stmt.close();
so the above seems to add data but it cannot be seen.
When I explicitly called
connectionPool.close();
Then and only then I could see the result.
I also tried to use JDBCDataSource and it worked as well.
So what is going on? And what is the right way to do this?
Your method of accessing the database from outside your application process is simply wrong.
Only one java process is supposed to connect to the file: database.
In order to achieve your aim, launch an HSQLDB server within your application, using exactly the same JDBC URL. Then connect to this server from the external client.
See the Guide:
http://www.hsqldb.org/doc/2.0/guide/listeners-chapt.html#lsc_app_start
Update: The OP commented that the external client was used after the application had stopped. Because you have turned the log off with hsqldb.log_data=false, nothing is persisted permanently. You need to perform an explicit CHECKPOINT or SHUTDOWN when your application completes its work. You cannot rely on shutdown=true at all, even without connection pooling.
See the Guide:
http://www.hsqldb.org/doc/2.0/guide/deployment-chapt.html#dec_bulk_operations
here i have got one issue.can some one please help me to resolve this.
i was trying to extract some data to DS 0FI_AP_6...
then in InfoPackage Monitor I can see like..
-->Requests (messages): Everything OK
-->Extraction (messages): Everything OK
-->Transfer (IDocs and TRFC): Missing messages or warnings
-->Info IDoc 2 : sent, not arrived ; IDoc ready for dispatch (ALE service)
Data Package 1 : 23752 Records arrived in BW
Data Package 2 : 15216 Records arrived in BW
Request IDoc : Application document posted
Info IDoc 1 : Application document posted
Info IDoc 3 : Application document posted
Info IDoc 4 : Application document posted
-->Processing (data packet): Everything OK
Data Package 1 ( 38672 Records ) : Everything OK
in Status Menu I am having message like...
Missing data packages for PSA Table
Diagnosis
Data packets are missing from PSA Table . BI processing does not
return any errors. The data transport from the source system to BI was
probably incorrect.
Procedure
Check the tRFC overview in the source system.
You access this log using the wizard or following the menu path
"Environment -> Transact. RFC -> Source System".
Error handling:
If the tRFC is incorrect, resolve the errors listed there.
Check that the source system is connected properly to BI. In
particular, check the remote user authorizations in BI.
Please suggest me how to resolve this issue...
thanks in advance for your help and quick reply is much appreciated.
But what the worst thing is I deleted the infopackage in PSA by mistake.
In the normal case, if I repeat the process again, the delta load would be OK, but now the delta load remains error.
so gurus,
1. how can I restart my delta loading correctly?
2. I want to modify the timestamp in the delta table, but how to do it ?
Go to T-Code RSA7 in the source system. This will tell you the date/timestamp that the delta is set to. If the date was changed to a range that no longer works then you will need to re-initialize the datasource in the BW system side. However, the Delta date may still be fine becauase it may have never been changed when you tried to first do your load because of the connection issues.
You can create a new infopackage and set the update to Initialize Datasource with Data Transfer. This will essentially run a full load from the datasource and then reset the delta pointer date/timestamp to when you ran it. This way you will capture all the data that you needed and anything that was already in the PSA should be overwritten.
Also note that you should delete or set the request status to red on the previous request that may contain bad data in the PSA.
From the original error it seems like you are having an RFC connection issue between the datasource and BW. Contact your BASIS support and have them check the connection to make sure it is good. To ensure that your datasource is extracting properly you can run t-code RSA3 on it in the source system. This will ensure that the extraction of data is working properly.