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Questions tagged [database-concurrency]

Database concurrency is a database property that allows users to access data at the same time.

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Orient db concurrency on edges and vertices

We have been struggling to create vertices on fly at the same time adding it to newly created class and add edge to it using regular blueprint query in multithreaded environment as some of the caching is causing problem and every time a query is…
Varun Tahin
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Avoiding deadlocks when running stored procedure on table WITH UPDLOCK, HOLDLOCK

I'm maintaining a stored procedure which will be executed whenever a user visits a web page. -- Existing tables CREATE TABLE SourceAccount ( Id bigint NOT NULL, Value varchar(50) NOT NULL, UpdateTime datetime2 NULL ) CREATE TABLE…
Dio Phung
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Concurrent incoming requests at web server

I have a question about the situation which arises during the flash sale in e-commerce websites. Assume there are only 5 items in stock and if 10000 requests hit the server at same instant, how does the server handle the requests and how does it…
Zephyr
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WPF : Update View Model when DB Changes (Concurrency Issue)

I'm currently working on WPF app that is architectured as follows: MVVM Entity Framwork 4 (with LINQ). WCF service that pool Database to get data (Oracle). I Make my WFC call in my View Model Class and put my data in an ObsevableCollections. Db…
Sami Errougui
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Concurrent posts and reads of a feed - missing entries when traversing from feed head to more recent entries

This is a classic concurrent read and write challenge: We are publishing records to and Atom Hopper feed on an Oracle database via Hibernate, and our partner is reading them. If we publish records 1 through 5, then 5 is the head (i.e. last…
Programmer Trond
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insert from select misses some rows - Postgres

We have a table with around 7M records with type ferrari and want to do a schema migration. We used this script insert into new_car id, name, type, colorType select id, name, type, 'red' from old_car where type = 'ferrari' order by id…
Nykolas Lima
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Error trying to fetch objects in core data "-[__NSArrayI entity] : unrecognized selector sent to instance"

I am trying to get all the data from Parse and to sync this data with the Core Data from my phone. I currently encounter a little problem with a fetch request that is not executing correctly. I think the cause is that I am using the…
C00kieMonsta
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How to handle Web application logic and database concurrency?

Let's say I have a table called items. User of my webapp can delete row of the items table, but I don't want to let the table empty. So currently I have code like this in my application: if (itemsCount() <= 1) { don't delete; } else { …
Teddy
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Any risk switching from NSConfinementConcurrencyType to NSPrivateQueueConcurrencyType and NSMainQueueConcurrencyType?

I have some legacy code using NSConfinementConcurrency for its CoreData and I switch the use of them to NSPrivateQueueConcurrencyType or NSMainQueueConcurrencyType. Any there any issues or risks switching from NSConfinementConcurrencyType to…
Boon
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How to prevent covering previous data when multi users update the same record in mysql?

User A and User B are modifying the same column of the same record,while A finishes,the value of the column changes. How to prevent B from covering the data that A inputs or just show some prompt? The method I used before is to add a column that…
johnny trs
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Mongo : Insert only if last document is different

Is there any concurrency-friendly way to do this in MongoDB : I want to insert a document only if the last document sorted by a field have a different value for another field. The goal is to have a collection that only stores transitions, instead of…
Erwan Swak
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Is there access conflict between users when they create/remove a global temp table in sql?

I have a SQL stored proc which is supposed to be executed by multiple users. Every user will execute this proc on the same server and same database. During the execution, it will create global temp tables and drop them at the end (for example,…
ChangeMyName
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Android SyncAdapter and concurrent write accesses

I am developing a RESTful Android app using SyncAdapter. I have watched some screencasts and read some tutorials, but they only address basic dynamics. Before starting to write the code, I would like to try and receive feedback from expert users…
Antonio Sesto
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Synchronize DataTable with MySQL database two ways

I have a DataSet/DataTable which I would like write changes to a MySQL database and if there are any changes in the MySQL database write those changes back to my DataSet/DataTable. In short: myDataSet -> MySQL database (user edits values) myDataSet…
flexo
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Can Oracle database transactions help in this scenario?

I am working with an Oracle database (11g Release 2). Imagine multiple connections doing the following simultaneously: Start transaction Check if a specific value exists in a table of unique values If the value does not exist, insert it Commit…
misha256
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