Solved

between SERIALIZABLE and SNAPSHOT

Posted on 2011-03-23
5
339 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
  • 2
  • 2
5 Comments
 
LVL 14

Assisted Solution

by:Daniel_PL
Daniel_PL earned 125 total points
ID: 35197300
0
 
LVL 143

Assisted Solution

by:Guy Hengel [angelIII / a3]
Guy Hengel [angelIII / a3] earned 125 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 125 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 125 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

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

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

Suggested Solutions

Hi all, It is important and often overlooked to understand “Database properties”. Often we see questions about "log files" or "where is the database" and one of the easiest ways to get general information about your database is to use “Database p…
Occasionally there is a need to clean table columns, especially if you have inherited legacy data. There are obviously many ways to accomplish that, including elaborate UPDATE queries with anywhere from one to numerous REPLACE functions (even within…
The Email Laundry PDF encryption service allows companies to send confidential encrypted  emails to anybody. The PDF document can also contain attachments that are embedded in the encrypted PDF. The password is randomly generated by The Email Laundr…
I've attached the XLSM Excel spreadsheet I used in the video and also text files containing the macros used below. https://filedb.experts-exchange.com/incoming/2017/03_w12/1151775/Permutations.txt https://filedb.experts-exchange.com/incoming/201…

685 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