Memory check which tables are loaded into memory

Great tip here for analysing whether you are over stretching your memory in SQL. The root of the issue is that clustered indexes are loaded into memory (the whole table is loaded) in order to query. Should your table be of a significant size, then all of your memory (or more) may be required to load a primary index in for querying. The solution to this is to remove the clustered index - this may equate to higher disk i/o however since the size of the index is smaller it may be able to load into memory anyhow.

A check for table memory usage is as follows:

SELECT sys.tables.name TableName,
sum(a.page_id)*8 AS MemorySpaceKB,
SUM(sys.allocation_units.data_pages)*8 AS StorageSpaceKB,
CASE WHEN SUM(sys.allocation_units.data_pages) <> 0 THEN
SUM(a.page_id)/CAST(SUM(sys.allocation_units.data_pages) AS NUMERIC(18,2))
END AS 'Percentage Of Object In Memory'
FROM (SELECT database_id, allocation_unit_id, COUNT(page_id) page_id FROM
sys.dm_os_buffer_descriptors GROUP BY database_id, allocation_unit_id) a
JOIN sys.allocation_units ON a.allocation_unit_id =
sys.allocation_units.allocation_unit_id
JOIN sys.partitions ON (sys.allocation_units.type IN (1,3)
AND sys.allocation_units.container_id = sys.partitions.hobt_id)
OR (sys.allocation_units.type = 2 AND sys.allocation_units.container_id
= sys.partitions.partition_id)
JOIN sys.tables ON sys.partitions.object_id = sys.tables.object_id
AND sys.tables.is_ms_shipped = 0
WHERE a.database_id = DB_ID()
GROUP BY sys.tables.name

For further information on this and perfmon settings, look here

TFS Event Subscription

Finally got round to looking into this. Firstly, the next iteration of the 2008 Power Tools will introduce a nicer interface for the maintenance of event subscriptions. However, that is not due quite yet so in the meantime there are two tools to fill the gap.

The TfsAlert tool provides a system tray app that balloon tips whenever events change. It monitors 8 different events, and allows filtering. The interface for filtering is to edit the config file, so knowledge of syntax is required. However, that syntax can be built by the next tool.

The second tool is TFS Event Subscription and is a GUI builder for event subscription strings. This allows you to subscribe to a particular event and get a message sent by SOAP, PlainText or EmailHTML. This is a standard feature of TFS, however this interface can be run on a client and is a great deal easier to use compared to command line.

Lastly, this blog provides details on how to amend the emails sent by TFS to point to the TFS Web Access for the work item, rather than a summary report.

Common SQL Server errors and failures

Blatant link, but very useful : Common SQL Server failures and errors

Clustered SQL Server error 28000 - cluster service login error

Whilst trial testing a failover for a clustered (W2K3) SQL Server 2005, we experienced an error 28000, failing on authenticating the cluster service account. This meant that the server service did not restart under cluster manager (though it is possible to start it from command prompt or via services).

This was due to removing the BUILTIN\Administrators group from security for SQL Server. Although this is standard practice, it appears that SQL Server is unable to verify the cluster serice account via an AD group. The solution to this is to either add back the BUILTIN\Administrators account (not desired) or create a security entry for the cluster service account.

SQL 2005 replication history

One of the shortcomings of the new replication monitor is it's lack of history. SQL 2000 was a lot better at this IMO. So, to get this information you need to create a report etc using SQL along these lines:

@subscriber NVARCHAR(256) = NULL
, @dateFrom DATETIME
, @dateTo DATETIME

SELECT ms.publisher
, ms.publisher_db
, ms.subscriber
, ms.subscriber_db
, mh.comments
, mh.[time]
FROM dbo.MSmerge_subscriptions ms
INNER JOIN dbo.MSmerge_agents ma
ON ms.subscriber = ma.subscriber_name
AND ms.subscriber_db = ma.subscriber_db
INNER JOIN dbo.MSmerge_sessions mse
ON ma.id = mse.agent_id
INNER JOIN dbo.MSmerge_history mh
ON mse.session_id = mh.session_id
AND mse.agent_id = mh.agent_id
WHERE ms.subscription_type = 0
AND (ms.subscriber + ':' + ms.subscriber_db = @subscriber OR @subscriber IS NULL)
AND mh.[time] BETWEEN @dateFrom AND @dateTo


To get the subscribers :

SELECT DISTINCT subscriber + ':' + subscriber_db AS subscriber
FROM dbo.MSmerge_subscriptions
WHERE subscription_type = 0

Skip SQL Statement when user does not have permission or linked server missing

Had an interesting problem with a stored procedure that checked replication history. This SP included a local and remote server using linked server. Occasionally the link would drop, and also whenever replication was rebuilt the user would forget to set up the permissions to the re-generated distribution database. Either of these situations throw errors in the SQL, so that it doesn't complete. To save redoing the existing reports, I needed a solution whereby the remote sql is skipped if it doesn't work. The solution seemed to be to use TRY..CATCH, however there is an issue with this. TRY..CATCH does not work with errors produced over a linked server. After some head scratching it was found that this could be overcome using EXEC sp_executesql. Since the SQL will not be in a plan (it is, afterall, on a different server) then there is no performance issue here either. So, the SQL read along the lines of :

BEGIN TRY
SET @sqlstmt = 'SELECT xxx FROM remoteserver.database.dbo.yyy'
EXEC sp_executesql
END TRY
BEGIN CATCH
--ignore error from remote system
END CATCH

Reporting Services Performance Monitoring

Useful technet article on how to monitor SSRS performance report by report.

http://technet.microsoft.com/en-us/library/aa964131.aspx