I have a problem understanding read consistency in database (Oracle). Suppose I am manager of a bank . A customer has got a lock (which I don't know) and is doing some updating. Now after he has got a lock I am viewing their account information and trying to do some thing on it. But because of read consistency I will see the data as ...
Could some one please help me understand when to use SNAPSHOT isolation level over READ COMMITTED SNAPSHOT in SQL Server? I understand that in most cases READ COMMITTED SNAPSHOT works, but not sure when go for SNAPSHOT isolation. Thanks ...
My BIRT report retrieves data using a SQL query (JDBC datasource). My SQL Server 2005 database is set to use snapshot transaction isolation. How do I define the transaction isolation mode in BIRT report designer ? Programatically it's done calling the datasource method setDefaultTransactionIsolation(4096) (4096 means snapshot isola...
How can I query the read/write ratio in Sql Server 2005? Are there any caveats I should be aware of? Perhaps it can be found in a DMV query, a standard report, a custom report (i.e the Performance Dashboard), or examining a Sql Profiler trace. I'm not sure exactly. Why do I care? I'm taking time to improve the performance of my web a...
I've written a linq-to-sql program that essentially performs an ETL task, and I've noticed many places where parallelization will improve its performance. However, I'm concerned about preventing uniquness constraint violations when two threads perform the following task (psuedo code). Record CreateRecord(string recordText) { using ...
Hi Every one! I have a query in LINQ, I want to get MAX of Code of my table and increase it and insert new record with new Code. just like the IDENTITY feature of SQL Server, but here my Code column is char(5) where can be alphabets and numeric. My problem is when inserting a new row, two concurrent processes get max and insert an equa...
I have a native query that does a batch insert into a MySQL database: String sql = "insert into t1 (a, b) select x, y from t2 where x = 'foo'"; EntityTransaction tx = entityManager.getTransaction(); try { tx.begin(); int rowCount = entityManager.createNativeQuery(sql).executeUpdate(); tx.commit(); ...
I have a question. Transaction isolation level is set to serializable. When the one user opens a transaction and INSERTs or UPDATEs data in "table1" and then another user opens a transaction and tries to INSERT data to the same table, does the second user need to wait 'til the first user commits the transaction? ...
I have a large web application using a COM data access layer against an SQL Server 2005 database. By default, the isolation level is READ_COMMITTED. Now I understand how READ_COMMITTED_SNAPSHOT isolation level works, and reading MSDN it says you can turn it on transparently. However, I'm still sceptical. :) Is it guaranteed, in an implem...
I'm still trying to run an app calling it from windows service. I tried to use the way described by Scott Allen. It works. But still I can't bring the app to the screen to interact with it. Help me pls. Even if I'm telling it to run the service using my credentials it doesn't bring the app on my desktop. tell me please how to get the cu...
How to trick UAC in Vista and Windows 7? How can I run something that needs not just administrator rights, but especially must be told to run as Administrator. I've tried start a process with given admin credentials, and even tried to use win32 function CreateProcessAsUser, but still unless I tell it manually "run as Administrator" it d...
Serializable transaction isolation levels avoids the problem of phantom reads by blocking any inserts to a table in a transaction which are conflicting with any select statements in other transactions. I am trying to understand it with an example, but it blocks insert even if when the filter in the select statement is not conflicting. I ...
c# application. I am doing a select followed by update of a column in a table. I am putting these in a separate transaction with isolation level set to Serializable. I am doing this to achieve data consistency. But still I can check that multiple users are able to read (select) the same value and eventually trying to update with the sa...
i need execute un update statement over an sql server table, this table is used by another process at the same time. because that sometimes deadlocks ocurs. wich Isolation Level do you recomend to avoid or minimize this deadlocks? ...
I'm working on a Flex/BlazeDS/Spring/JPA/Hibernate web application hooked up to a Microsoft SQL Server database. It seems to be locking the tables too aggresively. From my research, it looks like using the snapshot isolation policy is the best bet. I've set things up as such: <bean id="entityManagerFactory" class="org.springf...
I have a process that starts a transaction, inserts a record into Table1, and then calls a long running web service (up to 30 seconds). If the web service call fails then the insert is rolled back (which is what we want). Here is an example of the insert (it is actually multiple inserts into multiple tables but I am simplifying for thi...
I've always done transactions from within stored procedures but now I need to wrap a bunch of "dynamic" statements executed from code against sp_executesql in a transaction. Specifically I need the READ UNCOMMITED isolation level for these in some cases (I know what that does, and yes, that's what I need). This is SQL2008. My question ...
hi, I have a method SaveApp() which will deactivate the existing records and insert a new one. void SaveApp(int appID) { begin transaction; update; insert; commit transaction; } Let's say in database table SalesApp, I have 2 records with appID equal to 123; record 1, appID 123, inactive record 2, appID 123, active I...
We're using SQLAlchemy declarative base and I have a method that I want isolate the transaction level for. To explain, there are two processes concurrently writing to the database and I must have them execute their logic in a transaction. The default transaction isolation level is READ COMMITTED, but I need to be able to execute a piece ...
Hi All, Does someone knows a good book where transaction isolation levels are explained with examples and advices in what case what isolation level to use ? Regards ...