A mechanism for committing a consistent set of changes into a database atomically.

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21
votes
3answers
39k views

How to find out who deleted some data SQL Server

My boss had a query from a customer yesterday asking how they could find out who deleted some data in their SQL Server database (it is the express edition if that matters). I thought this could be ...
14
votes
1answer
8k views

SQL query for combinations without repetition

I need a query which can be used in (or as) a function and retrieves all combinations of n values. And I need all combinations of length k where k = 1..n. Extended sample input and result so input ...
6
votes
2answers
17k views

SQL Server Transaction Timeout

Is there a way in SQL Server 2008 R2 to cause a timeout for a database modification involving a transaction? We have a scenario where our application code hangs or throws an exception and fails to ...
2
votes
1answer
399 views

select for update gives error on indexed column

here is my code: mysql_query("start transaction"); $q="select max(id) from test for update"; $r=mysql_query($q); $row=mysql_fetch_array($r); for ($k=0;$k<100000;$k++) { $q="insert into test values ...
6
votes
3answers
3k views

SQL Server - what isolation level for non-blocking select statements?

I have a long running transaction (called, say, T1) that performs some deletes, updates and inserts on a table in SQL Server 2008 R2. At the same time, another process periodically runs select ...
3
votes
2answers
360 views

How to minimize log operations in SQL Server to avoid “log full” error

I have a database in production which constantly get log file filled, its a data warehouse and have many jobs/queries running for obvious. Below is the error which I am getting Msg 9002, Level 17, ...
3
votes
2answers
695 views

read before write transaction

Talking about transactions (db transactions), does a read operation have always precede a write operation? That's obvious, isn't it? Thanks in advance *Of course my question doesn't take into ...
33
votes
4answers
26k views

What risks are there if we enable read committed snapshot in sql-server?

I have read here that some extra data will be stored per row so we might see a performance degradation but what other risks are there? eg. Will this affect recovery of the database? Is there anything ...
26
votes
2answers
14k views

Is it a bad practice to always create a transaction?

Is it a bad practice to always create a transaction? For example, it is a good practice to create a transaction for nothing but one simple SELECT? What is the cost of creating a transaction when it ...
14
votes
1answer
8k views

Trigger in combination with transaction

Suppose we have the following situation: We have a table (let's say Table_A), wich has a trigger on INSERT. The trigger job is to update some rows in table_B based on the inserted values in table_A. ...
20
votes
7answers
13k views

Oracle - Any way to view uncommited changes to a particular table?

I'm debugging through a batch process currently that does a lot of DML statements, but doesn't do a commit right away. It would be nice to be able to view the "pending" changes from another session ...
11
votes
1answer
5k views

How to use transactions with SQL Server DDL?

I have a login table into which all inserts are done by a single stored procedure. CREATE TABLE dbo.LogTable( LogRefnr int IDENTITY(1, 1) NOT NULL, LogQuery varchar(255) NOT NULL, LogTime ...
8
votes
1answer
553 views

In case of multiple updates of the same record in a single transaction, how many versions are being stored?

According to MSDN article by Kimberly L. Tripp, Neal Graves's "SQL Server 2005 Row Versioning-Based Transaction Isolation "... All the earlier versions of a particular record are chained in a linked ...
7
votes
2answers
191 views

Can I use transaction logs to rebuild a database?

We've had some data loss and don't have a reliable backup it seems. We do have HUGE transaction logs and there was some thought that we might be able to use these to get back to a certain point. Is ...
6
votes
1answer
133 views

Does RCSI use less or same space than SNAPSHOT? Why?

Trying to better understand row-versioning based transaction isolations - RCSI (Read Committed Snapshot Isolation and SNAPSHOT) - in SQL Server... MSDN online article "Choosing Row Versioning-based ...
5
votes
3answers
3k views

Using MySQL triggers or transactions?

I want to ask your opinion in using MySQL triggers or transactions in a website. Actually I have a history payment table with - UserId | OperationId | Comment | Credits | Sign (debit or credit). So ...
4
votes
1answer
133 views

Why do row-versioning isolations use a linked list of versions of record? [closed]

Trying to better understand row-versioning based transaction isolations in SQL Server... According to Kimberly L. Tripp, Neal Graves's "SQL Server 2005 Row Versioning-Based Transaction Isolation": ...
3
votes
1answer
2k views

MySQL Insert into two tables using new IDs

I'm trying to select data already in the database and insert it into two tables using the generated ID from table one. table1 contains configuration options, table2 contains pricing data. Table2 uses ...
2
votes
1answer
2k views

Transaction Lock Timeouts When Updating a Row

I'm trying to determine the cause of an InnoDB transaction lock timeout. This one is very strange in that it appears to be a deadlock error instead - nonetheless, here's the output of my slow log ...
6
votes
3answers
3k views

Will the transaction log shrink automagically in SQL Server?

When SQL Server database in a SIMPLE mode, you don't have to care about the transaction log bakcups. But in a SIMPLE mode, the transaction log seems to grow as it does in FULL mode. Does is truncate ...
12
votes
1answer
7k views

MySQL transaction size - how big is too big?

I have an import process that runs every so often and I want it to be an 'all or nothing' kind of deal, aka: a transaction. There are many aspects, and the imports may yield anywhere between ...
6
votes
2answers
8k views

Transaction and Try-catch in SQL Server Job

We have DML operations in each step of a SQL Server job. To ensure the update/insert will be rolled back in case something goes wrong, I have wrapped the data modifications of each step in TRY CATCH ...
3
votes
2answers
2k views

How do I implement insert-if-not-found for transactions at serializable isolation level?

I'm having a hard time figuring out how to exactly implement a 'insert if not found' function. Consider the following. We have a table called artist with 2 columns, (name, id) where name is the ...
7
votes
1answer
156 views

Is there a performance difference in committing and rolling back a read-only transaction?

I open a (repeatable read) transaction (BEGIN TRAN) to do some work on certain records. First thing I do is checking if the data I need to change is in the database. In some cases there will be and ...
7
votes
1answer
4k views

Deleting MySQL table with pending transactions

Is there a way to delete an InnoDB table or database with pending transactions in MySQL (preferably on file system level)? What happened: I use MySQL 5.5.28 and ran LOAD DATA INFILE… to import a ...
6
votes
3answers
11k views

sleeping SPID blocking other transactions

I'm really having trouble tracking down some blocking we are experiencing. The root blocking SPID's status is 'sleeping', the cmd is 'AWAITING COMMAND', and the sqltext is 'SET TRANSACTION ISOLATION ...
4
votes
2answers
433 views

What happens if a client connection is killed while holding a lock?

What happens if a client establishes a transaction, locks a row or table, and the client process crashes before it has a chance to rollback or commit the transaction? What, if anything, does SQL ...
2
votes
1answer
729 views

Distributed - across multiple databases or servers - Transactions

I have some doubts related to transactions in SQL. I perform below steps. Connection 1 open for DB1 database Begin transaction for Connection 1 Run the commands on Connection 1 Connection 2 open for ...
1
vote
1answer
84 views

SSIS Transaction Problem

I am trying to use SQL transaction with my SSIS package so if any error comes changes are rollback. I am using an "Sequence Container" in Control Flow for this and setting its "Transaction Option" to ...
1
vote
1answer
113 views

How does the transactions interact if you set a different isolation level per connection?

I read that I can have different isolation levels per connection and in the server. The default isolation level is REPEATABLE-READ. So if I have a transaction that issues a SERIALIZED to the client ...
1
vote
2answers
1k views

How to avoid locks by large transactions?

We have a large application running, that requires cleanup for performance reasons. This was however not forseen when designing the application. Basically, the delete is executed from a stored ...
1
vote
1answer
527 views

MYSQL MyISAM data recovery implementation

I am creating integration into eshop script, shop is using MyISAM tables and I need to implement something like transactions in InnoDB, what I actually need is full recovery of data after modifying or ...
0
votes
1answer
101 views

How to determine which statement is blocking an update in SQL Server

We have an UPDATE statement running in a large J2EE application that is getting blocked by some other statement. The update is using the primary key, so it should affect only one row. The isolation ...