isolation-level

I have an application that uses hibernate version 3.6.4, and c3p0 version 0.9.1.2 for connection pooling. My underlying RDBMS is MySql version 5.0.67. My installation of MySql indicates that the default transaction isolation level is "REPEATABLE-READ" (4): mysql> select @@GLOBAL.tx_isolation, @@tx_isolation; +-----------------------+-----------------+ | @@GLOBAL.tx_isolation | @@tx_isolation | +-----------------------+-----------------+ | REPEATABLE-READ | REPEATABLE-READ | +-----------------------+-----------------+ I have not changed or configured the transaction isolation level within

I am writing a web application where two different users can update a list of things, to do list, for example. I have come to realize that, optimistic locking mechanism works best since I don't expect high contention. I was looking at transaction isolation levels and now I am a little confused. Looks like different transaction isolation levels also solve similar problems. How are these two different concepts related to each other? If possible, with a simple example. Both of these things are related to data consistency and concurrent access, but they are two different mechanisms. Locking

In MS SQL Server is there a way to detect whether a database has had its isolation level set via the T-SQL command ALTER DATABASE <database> SET READ_COMMITTED_SNAPSHOT ON; I cannot find a simple way to detect this in either T-SQL or via the Management Studio's GUI. TIA Galwegian SELECT is_read_committed_snapshot_on FROM sys.databases WHERE name= 'YourDatabase' Return value: 1 : READ_COMMITTED_SNAPSHOT option is ON . Read operations under the READ COMMITTED isolation level are based on snapshot scans and do not acquire locks. 0 (default): READ_COMMITTED_SNAPSHOT option is OFF . Read operations

I have an utility method creating TransactionScope in my application. I want to do a unit test to validate that the returned TransactionScope has the correct IsolationLevel set, to be sure that nobody can modify the code without breaking the tests. System.Transactions.Transaction scope does not have public properties exposing information like that. ( http://msdn.microsoft.com/en-us/library/system.transactions.transactionscope.aspx ) Any way to get this information? Can you run a SQL query to check the isolation level: SELECT CASE transaction_isolation_level WHEN 0 THEN 'Unspecified' WHEN 1

The documentation I've run across researching this indicates that the way to do it for other databases is to use multiple statements in your query, a la: >>> cursor = connection.cursor() >>> cursor.execute("set session transaction isolation level read uncommitted; select stuff from table; set session transaction isolation level repeatable read;") Unfortunately, doing that yields no results, as apparently the Python DB API (or maybe just this implementation of it?) doesn't support multiple recordsets within a single query. Has anyone else had success with this in the past? I don't think this

I have the following T-SQL code: SET TRANSACTION ISOLATION LEVEL SERIALIZABLE BEGIN TRANSACTION T1_Test /*This is a dummy table used for "locking" and it doesn't contain any meaningful data.*/ UPDATE lockTable SET ID = 1 WHERE ID = 1 DECLARE @Count TINYINT SELECT @Count = COUNT(*) FROM debugSP WAITFOR DELAY '00:00:5'; INSERT INTO debugSP (DateCreated, ClientId, Result) SELECT GETDATE(), @@SPID, @Count COMMIT TRANSACTION T1_Test I am using "locking" hack marked with comment to acquire the exclusive lock. NOTE: using TABLOCKX or UPDLOCK hints will not work because I have broken ATOMIC-ity by

I have a web application running in Tomcat 6, and I've managed to configure it to use the built-in DBCP connection pooling, and all is working very well, however I suspect it is running in the wrong isolation level on the database. I'd like it to run in read uncommitted, but I think it's running in read committed and don't know how to set it. Here is my context's XML file: <?xml version="1.0" encoding="UTF-8"?> <Context antiResourceLocking="false" privileged="true"> <Resource name="jdbc/Connection" auth="Container" type="javax.sql.DataSource" maxActive="100" maxIdle="30" maxWait="10000"