SQL Clone
SQLServerCentral is supported by Redgate
 
Log in  ::  Register  ::  Not logged in
 
 
 


FILESTREAM storage requirement


FILESTREAM storage requirement

Author
Message
Abhijit More
Abhijit More
SSCommitted
SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)SSCommitted (1.9K reputation)

Group: General Forum Members
Points: 1885 Visits: 767
To enable the FILESTREAM filegroups, you must set READ_COMMITTED_SNAPSHOT and ALLOW_SNAPSHOT_ISOLATION to OFF.

Why?

Abhijit - http://abhijitmore.wordpress.com
sql_lock
sql_lock
Hall of Fame
Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)Hall of Fame (3.2K reputation)

Group: General Forum Members
Points: 3217 Visits: 1996
@PaulRandal writes a excellent article..

http://msdn.microsoft.com/en-us/library/cc949109.aspx

Isolation Semantics

The isolation semantics are governed by database engine transaction isolation levels. When FILESTREAM data is accessed through the Win32 APIs, only the read-committed isolation level is supported. Transact-SQL access also allows the repeatable-read and serializable isolation levels. Furthermore, using Transact-SQL access, dirty reads are permitted through the read-uncommitted isolation level, or the NOLOCK query hint, but such access will not show in-flight updates of FILESTREAM data.

The file system access open operations do not wait for any locks. Instead, the open operations fail immediately if they cannot access the data because of transaction isolation. The streaming API calls fail with ERROR_SHARING_VIOLATION if the open operation cannot continue because of isolation violation.

jacob sebastian
jacob sebastian
SSCrazy
SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)SSCrazy (2.5K reputation)

Group: General Forum Members
Points: 2534 Visits: 2523
The 'WHY' part is still a mystery and one possible reason could be the way SNAPSHOT isolation works. Under snapshot isolation level, your transaction should be able to read a snapshot of the database as of the time when the transaction starts. For the NON-FILESTREAM data, SQL Server implements this by keeping versions of the data in tempdb database.

When it comes to the FILESTREAM data, which is stored in the NTFS - not in the table - and which may be huge blob files, this may not be a trivial task to implement a similar versioning mechanism.

That '**could be**' be the reason why SNAPSHOT isolation is not supported with FILESTREAM.

.
Go


Permissions

You can't post new topics.
You can't post topic replies.
You can't post new polls.
You can't post replies to polls.
You can't edit your own topics.
You can't delete your own topics.
You can't edit other topics.
You can't delete other topics.
You can't edit your own posts.
You can't edit other posts.
You can't delete your own posts.
You can't delete other posts.
You can't post events.
You can't edit your own events.
You can't edit other events.
You can't delete your own events.
You can't delete other events.
You can't send private messages.
You can't send emails.
You can read topics.
You can't vote in polls.
You can't upload attachments.
You can download attachments.
You can't post HTML code.
You can't edit HTML code.
You can't post IFCode.
You can't post JavaScript.
You can post emoticons.
You can't post or upload images.

Select a forum

































































































































































SQLServerCentral


Search