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

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16
votes
3answers
22k 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 ...
9
votes
1answer
3k 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 ...
2
votes
1answer
268 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
2k 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 ...
4
votes
2answers
9k 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 ...
3
votes
2answers
411 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 ...
24
votes
3answers
16k 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 ...
15
votes
7answers
7k 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 ...
7
votes
1answer
3k 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
207 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
188 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
72 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 ...
3
votes
1answer
90 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
1k 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 ...
3
votes
2answers
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 ...
2
votes
1answer
953 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
1answer
3k 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. ...
13
votes
2answers
3k 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 ...
5
votes
3answers
2k 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 ...
3
votes
2answers
921 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 ...
5
votes
1answer
2k 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 INFILEā€¦ to import a ...
1
vote
1answer
66 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
1answer
244 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 ...