We have an Oracle SOA Composite that is deployed on Weblogic 11g. There is a trigger in a mySQL database that kicks off the composite. When it runs with a new entry the account name is not being populated so I added an additional query for the account name. I have included a screenshot of the check I have to query account name.
It appears the corresponding table is not getting updated as fast as the table that the trigger is on. I tried putting a wait in the composite and that didn't work. I also tried a wait with a while loop, which hung the composite. Does anyone have any suggestions on how to handle a situation like this?
Thanks,
Tom
This was actually an issue with the composite assignments were incorrect and the query did not return any data.
Related
I queried the user_tables view of sys.all_tables and saw a column called LOGGING which is set to either YES or NO. This is an Oracle 11g database. I am not too familiar with the specifics of Oracle databases.
I just want to find out what that parameter does. What kind of logging are we talking about?
I am interested in finding out if there is any connection between this parameter and the CREATED and LAST_MODIFIED fields usually available in Oracle based applications.
Also does this logging parameter also enable logging of data changes (INSERT, UPDATE, DELETE) including old and new values of fields changed?
Appreciate your help folks!
Sort of. The documentation describes the column thusly:
Indicates whether or not changes to the table are logged; NULL for partitioned tables
The relates to the LOGGING clause in the CREATE TABLE statement:
Specify whether the creation of the table and of any indexes required
because of constraints, partition, or LOB storage characteristics will
be logged in the redo log file (LOGGING) or not (NOLOGGING).
This is separately documented, along with a lot more information. Simply put this indicates whether changes made to the table are being logged so that they can be recovered in the event of an instance failure. It is not so you can reference changes; you'll have to use triggers or a materialized view for that.
I have asked a few questions today as I try to think through to the solution of a problem.
We have a complex data structure where all of the various entities are tightly interconnected, with almost all entities heavily reliant/dependant upon entities of other types.
The project is a website (MVC3, .NET 4), and all of the logic is implemented using LINQ-to-SQL (2008) in the business layer.
What we need to do is have a user "lock" the system while they make their changes (there are other reasons for this which I won't go into here that are not database related). While this user is making their changes we want to be able to show them the original state of entities which they are updating, as well as a "preview" of the changes they have made. When finished, they need to be able to rollback/commit.
We have considered these options:
Holding open a transaction for the length of time a user takes to make multiple changes stinks, so that's out.
Holding a copy of all the data in memory (or cached to disk) is an option but there is heck of a lot of it, so seems unreasonable.
Maintaining a set of secondary tables, or attempting to use session state to store changes, but this is complex and difficult to maintain.
Using two databases, flipping between them by connection string, and using T-SQL to manage replication, putting them back in sync after commit/rollback. I.e. switching on/off, forcing snapshot, reversing direction etc.
We're a bit stumped for a solution that is relatively easy to maintain. Any suggestions?
Our solution to a similar problem is to use a locking table that holds locks per entity type in our system. When the client application wants to edit an entity, we do a "GetWithLock" which gets the client the most up-to-date version of the entity's data as well as obtaining a lock (a GUID that is stored in the lock table along with the entity type and the entity ID). This prevents other users from editing the same entity. When you commit your changes with an update, you release the lock by deleting the lock record from the lock table. Since stored procedures are the api we use for interacting with the database, this allows a very straight forward way to lock/unlock access to specific entities.
On the client side, we implement IEditableObject on the UI model classes. Our model classes hold a reference to the instance of the service entity that was retrieved on the service call. This allows the UI to do a Begin/End/Cancel Edit and do the commit or rollback as necessary. By holding the instance of the original service entity, we are able to see the original and current data, which would allow the user to get that "preview" you're looking for.
While our solution does not implement LINQ, I don't believe there's anything unique in our approach that would prevent you from using LINQ as well.
HTH
Consider this:
Long transactions makes system less scalable. If you do UPDATE command, update locks last until commit/rollback, preventing other transaction to proceed.
Second tables/database can be modified by concurent transactions, so you cannot rely on data in tables. Only way is to lock it => see no1.
Serializable transaction in some data engines uses versions of data in your tables. So after first cmd is executed, transaction can see exact data available in cmd execution time. This might help you to show changes made by user, but you have no guarantee to save them back into storage.
DataSets contains old/new version of data. But that is unfortunatelly out of your technology aim.
Use a set of secondary tables.
The problem is that your connection should see two versions of data while the other connections should see only one (or two, one of them being their own).
While it is possible theoretically and is implemented in Oracle using flashbacks, SQL Server does not support it natively, since it has no means to query previous versions of the records.
You can issue a query like this:
SELECT *
FROM mytable
AS OF TIMESTAMP
TO_TIMESTAMP('2010-01-17')
in Oracle but not in SQL Server.
This means that you need to implement this functionality yourself (placing the new versions of rows into your own tables).
Sounds like an ugly problem, and raises a whole lot of questions you won't be able to go into on SO. I got the following idea while reading your problem, and while it "smells" as bad as the others you list, it may help you work up an eventual solution.
First, have some kind of locking system, as described by #user580122, to flag/record the fact that one of these transactions is going on. (Be sure to include some kind of periodic automated check, to test for lost or abandoned transactions!)
Next, for every change you make to the database, log it somehow, either in the application or in a dedicated table somewhere. The idea is, given a copy of the database at state X, you could re-run the steps submitted by the user at any time.
Next up is figuring out how to use database snapshots. Read up on these in BOL; the general idea is you create a point-in-time snapshot of the database, do whatever you want with it, and eventually throw it away. (Only available in SQL 2005 and up, Enterprise edition only.)
So:
A user comes along and initiates one of these meta-transactions.
A flag is marked in the database showing what is going on. A new transaction cannot be started if one is already in process. (Again, check for lost transactions now and then!)
Every change made to the database is tracked and recorded in such a fashion that it could be repeated.
If the user decides to cancel the transaction, you just drop the snapshot, and nothing is changed.
If the user decides to keep the transaction, you drop the snapshot, and then immediately re-apply the logged changes to the "real" database. This should work, since your requirements imply that, while someone is working on one of these, no one else can touch the related parts of the database.
Yep, this sure smells, and it may not apply to well to your problem. Hopefully the ideas here help you work something out.
I need to manage the acquisition of many record at hour. About 1000000 records. And I need to get every second the last insert value for every primary key. It works quit well with sharding. I was thinking to try the use os capped collection to get only the last record for every primary key. In order to do this, I made two separated insert, there is a way, into mongodb, to make some kind of trigger to propagate the insert into a collection to another collection?
MongoDB does not have any support for triggers or similar behavior.
The only way to do this is to make it happen in your code. So the code that writes the first entry should also write the second.
People have definitely requested triggers. If they are necessary for your solution, please cast a vote on the feature request.
I disagree with "triggers is needed". People, MongoDB was created to be very fast and to provide as basic functionalities as can be. This is a power of this solution.
I think that here the best think is to create triggers inside Your application as a part of Data Access layer.
I have the scenario like this,
My environment is .Net2.0, VS 2008, Web Application
I need to lock a record when two members are trying to access at the same time.
We can do it in two ways,
By Front end (putting the sessionID and record unique number in the dictionary and keeping it as a static or application variable), we will release when the response is go out of that page, client is not connected, after the post button is clicked and session is out.
By backend (record locking in the DB itself - need to study - my team member is looking ).
Is there any others to ways to do and do I need to look at other ways in each and every steps?
Am I missing any conditions?
You do not lock records for clients, because locking a record for anything more than a few milliseconds is just about the most damaging thing one can do in a database. You should use instead Optimistic Concurrency: you detect if the record was changed since the last read and re-attempt the transaction (eg you re-display the screen to the user). How that is actually implemented, will depend on what DB technology you use (ADO.Net, DataSets, Linq, EF etc).
If the business domain requires lock-like behavior, those are always implemented as reservation logic in the database: when a record is displayed, it is 'reserved' so that no other users can attempt to make the same transaction. The reservation completes or times out or is canceled. But a 'reservation' is never done using locks, is always an explicit update of state from 'available' to 'reserved', or something similar.
This pattern is also describe din P of EAA: Optimistic Offline Lock.
If your talking about only reading data from a record from SQL server database, you don't need to do anything!!! SQL server will do everything about managing multi access to records. but if you want to manipulate data, you have to use Transactions.
I agree with Ramus. But still if u need it. Create a column with name like IsInUse as bit type and set it true if one is accessing. Since other guys will also need same data at same time then u need to save your app from crash .. so at every place from where the data is retrieved you have to put a check if IsInUse is False or not.
I am using Enterprise block and not able to figure this out.
I am using oracle procedure for inserting records into the database from my asp.net application in VB.net
Though it is inserting records as it should When I try to access the dataset returned I am not able to see the just inserted record details.
In my Oracle procedure I have Output Cursor which should return several column values from the just inserted record.
Please help.
This is a bit of a work around to what you're currently doing, but if you're still having issues with this, I'd suggest running ExecuteNonQuery for inserting and then ExecuteDataTable with the data you supplied to call a SELECT on your data.
Keep in mind, however, that this method's performance may be a bit slower (DB call to insert, followed by a DB call and return to select the data), but you will not need to worry about your cursor anymore (not sure what kind of performance gain, if any, this might have).