SQL blocking a Procedure causing my SharePoint site unavailable

Hello, I am working on a SharePoint environment and I am not very much expert in SQL databases. In my environment there are 2 App Servers, 2 WFE and 1 DB server. I have 3 site collections, and the size of the one Content DB is more than 200GB, other 2 are 120GB and 100GB.

Currently I am facing an issue, that my SharePoint Portal goes down, and on further investigation we found out that there is a SQL deadlock causing the long queue in SQL that we kill manually and afterwards the site comes up and running.
The SQL Procedure that is being blocked is a stored procedure call SPROD_Contect_Intranet.dbo.pro_getStreamsForSite.
On a daily basis we get 40 to 50 plus blocks and we have to manually kill it.

The procedure name is SPPROD_Content_Intranet.dbo.proc_GetStreamsForSite, and the function which is blocking the SQL is INDEX REORGANIZE, What I can see here is very long wait situation which may not be unlocked until “INDEX REORGANIZE” is completed while another command is inserting a record into the same table. Also the SELECT command from the proc_GetStreamsForSite locked the table to get the siteID using the clustered index DocStreams_CI which is under “INDEX REORGANIZE” status. To me the situation looks almost in a dead-locked situation if not force to kill the blocking process which is the proc_GetStreamsForSite.”

Please suggest what could be the root cause and how to resolve it? Many Thanks,
LVL 1
rjkirbyAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Vitor MontalvãoMSSQL Senior EngineerCommented:
Question here is why it needs the INDEX REORGANIZE command?
Index maintenance should only occurs in non working hours because the impact is very high since it's causing locks.
When the SP is running and who is calling it?
Can you post the full code of the SP here?
0
rjkirbyAuthor Commented:
Thanks Vitor for your expert opinion.

There are 4 built in rules in SharePoint that are related to fragmented indices, and these runs when SQL thinks it should run (when it needs to re organize index and have resources).  And I am not 100% sure if the 4 rules are causing the SQL Locks. The 4 SharePoint rules are :

1 - Databases used by SharePoint have fragmented indices
2 - Search – One or more property databases have fragmented indices.
3 - Search - One or more crawl databases may have fragmented indices
4 - Search - One or more crawl databases may have fragmented indices

Microsoft Link on it - http://technet.microsoft.com/en-us/library/cc262731(v=office.14).aspx 

SQL Code:

1.      There were 33 processes blocked by proc_GetStreamsForSite.

a.      proc_GetStreamsForSite is selecting information from a function called TVF_DocStreams_SiteId as below.
 
SELECT
        DS.ExpirationUTC, DS.DocId, DS.SiteId, DS.Partition, DS.BSN, NULL, DS.Type, DS.Size, CASE WHEN DS.Size > @ChunkSize AND DS.Content IS NOT NULL THEN SUBSTRING(DS.Content, 1, @ChunkSize) ELSE DS.Content END, dbo.fn_RbsReference(DS.RbsId)
    FROM
        TVF_DocStreams_SiteId(@SiteId) AS DS
    WHERE
        (@IncludeRbs = 1 OR DS.RbsId IS NULL) AND
        (@IncludeInline = 1 OR DS.Content IS NULL)
 
The function TVF_DocStreams_SiteId is selecting information from the table called DocStreams as below.
    SELECT
        *
    FROM
        [dbo].[DocStreams] WITH (INDEX=DocStreams_CI, FORCESEEK)
    WHERE
        SiteId = @SiteId
 
 
2.      Among the blocked processes, I am very much interested in this one - ALTER INDEX [DocStreams_CI] ON [dbo].[DocStreams] REORGANIZE

b.      The index DocStreams_CI is a Clustered index which physically ordering the table by the configured columns order.

3.      Also Among them, majority of them were proc_WriteStreamToSQL.

c.      This stored proc has a command “INSERT INTO DocStreams (SiteId, DocId, Partition, BSN, Size, Content, RbsId, Type, ExpirationUTC) VALUES (@SiteId, @DocId,…”
 
What I can see here is very long wait situation which may not be unlocked until “INDEX REORGANIZE” is completed while another command is inserting a record into the same table.

Also the SELECT command from the proc_GetStreamsForSite locked the table to get the siteID using the clustered index DocStreams_CI which is under “INDEX REORGANIZE” status.
To me the situation looks almost in a dead-locked situation if not force to kill the blocking process which is the proc_GetStreamsForSite.
 

Thanks,
0
Vitor MontalvãoMSSQL Senior EngineerCommented:
The article you posted are the usual maintenance tasks for any database (SharePoint or not) and they recommend to run those plans in non-production hours:
We recommend that you run consistency checks during non-production hours because DBCC CHECKDB is extremely resource-intensive (I/O, CPU, memory, and tempdb space).
(...)
Even if online index rebuild is used, there are still two points in the operation where table locks are held momentarily, and these could cause blocking. As a result, we recommend that you always schedule index rebuild activities during periods of low activity.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
KuppingerCole Reviews AlgoSec in Executive Report

Leading analyst firm, KuppingerCole reviews AlgoSec's Security Policy Management Solution, and the security challenges faced by companies today in their Executive View report.

rjkirbyAuthor Commented:
Thanks Vitor. Are these Index Rebuild activities triggered by SharePoint or SQL itself? as I plan to disable my 4 SharePoint Rules and see if we are still facing locks, these 4 rules are related with the SharePoint Databases indices fragmentation. Many Thanks,
0
Vitor MontalvãoMSSQL Senior EngineerCommented:
Can be triggered from anywhere but the user that trigger it need to have the permissions for reindex.
0
rjkirbyAuthor Commented:
Thanks Vitor. You are right, these 4 jobs that are triggered by SharePoint have Full rights on SQL DB so it could be the reason. Since 1 week we haven't experienced any locks so far.
0
Vitor MontalvãoMSSQL Senior EngineerCommented:
That's good. Just schedule the reindex to run in non-productive periods and you won't have any issues with that.
0
rjkirbyAuthor Commented:
Thanks Vitor.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Application Servers

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.