Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

between SERIALIZABLE and SNAPSHOT

Posted on 2011-03-23
5
Medium Priority
?
348 Views
Last Modified: 2012-05-11
Hey experts, I've read about
 SET TRANSACTION ISOLATION LEVEL (Transact-SQL)
 http://msdn.microsoft.com/es-es/library/ms173763 (v = SQL.100). aspx
but i do not understand
 I would like to know the difference between SERIALIZABLE and SNAPSHOT
0
Comment
Question by:enrique_aeo
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 14

Assisted Solution

by:Daniel_PL
Daniel_PL earned 500 total points
ID: 35197300
0
 
LVL 143

Assisted Solution

by:Guy Hengel [angelIII / a3]
Guy Hengel [angelIII / a3] earned 500 total points
ID: 35197310
SNAPSHOT will take a snaphshot of the table(s) involved for the transaction, so you will keep to get the same information, whatever the other sessions are doing. the other sessions are not blocked whatsoever
SERIALIZABLE will block/delay all the others to do anything on the same objects you lock until your transaction is completed. this is a very strong locking, and needs to be used carefully
0
 

Author Comment

by:enrique_aeo
ID: 35197462
angelIII... the SNAPSHOT need more space to do their SNAPSHOT?
 and when you delete that copy?. Could you explain a little more about SNAPSHOT
0
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 35197474
the snapshot is only "virtual", means that there is no snapshot data unless you try to access tables which are getting modified (by other processes). in short, the snaphot is only a list of data blocks that have been modified since you started the "snapshot transaction", so as long as the transaction is short, there will be almost no "changes" stored for "your snapshot".
0
 
LVL 14

Assisted Solution

by:Daniel_PL
Daniel_PL earned 500 total points
ID: 35197520
In Snapshot Isolation level updated row versions for each transaction are maintained in TempDB.
After transaction has begun, it ignores all the newer rows inserted or updated in your table.
0

Featured Post

Back Up Your Microsoft Windows Server®

Back up all your Microsoft Windows Server – on-premises, in remote locations, in private and hybrid clouds. Your entire Windows Server will be backed up in one easy step with patented, block-level disk imaging. We achieve RTOs (recovery time objectives) as low as 15 seconds.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

INTRODUCTION: While tying your database objects into builds and your enterprise source control system takes a third-party product (like Visual Studio Database Edition or Red-Gate's SQL Source Control), you can achieve some protection using a sing…
In this article I will describe the Backup & Restore method as one possible migration process and I will add the extra tasks needed for an upgrade when and where is applied so it will cover all.
Video by: ITPro.TV
In this episode Don builds upon the troubleshooting techniques by demonstrating how to properly monitor a vSphere deployment to detect problems before they occur. He begins the show using tools found within the vSphere suite as ends the show demonst…
This is my first video review of Microsoft Bookings, I will be doing a part two with a bit more information, but wanted to get this out to you folks.

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question