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6
votes
4answers
2k views

MySQL InnoDB locks primary key on delete even in READ COMMITTED

Preface Our application runs several threads that execute DELETE queries in parallel. The queries affect isolated data, i.e. there should be no possibility that concurrent DELETE occurs on the same ...
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 ...
4
votes
2answers
413 views

Does SQL Server place shared locks on scanned records when using REPEATABLE READ

Assume a SQLCmd session which is using transaction isolation level REPEATABLE READ. In this session I start a transaction and execute an UPDATE statement with a WHERE clause on a non indexed column. ...
3
votes
1answer
104 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": ...
16
votes
3answers
3k views

Managing concurrency when using SELECT-UPDATE pattern

Let's say you have the following code (please ignore that it's awful): BEGIN TRAN; DECLARE @id int SELECT @id = id + 1 FROM TableA; UPDATE TableA SET id = @id; --TableA must have only one row, ...
4
votes
1answer
2k views

How to force the use of row locks?

I am trying to get my table to use row locks. I have already disabled lock escalation. The isolation level is READ_COMMITTED_SNAPSHOT alter table <TABLE_NAME> SET (LOCK_ESCALATION=DISABLE) go ...
4
votes
3answers
453 views

Does Snapshot Isolation only give you what has been commited? (And General Snapshot Isolation questions.)

So, I have some deadlocking issues. I have seen two options to resolve it. Add read uncommitted to my db or do Snapshot Isolation and add read committed snapshot. After doing some research into ...