Month: October 2017

I was recently trying to work out why SSAS installed on the same server as SQL Server would not use shared memory for its processing connections. It may be obvious to some people, but an internet search turns up surprising few references: the Shared Memory Protocol is not Supported on SQL Server Failover Clusters.

On a standard SQL Server instance, the Shared Memory protocol can be used when a client is running on the same computer as the SQL Server instance and the Shared Memory Protocol is enabled in SQL Server’s network protocols. (You can check the status of the enabled protocols using SQL Server Configuration Manager).

sys.dm_exec_connections will show you which net transport a client connection is using:

SELECT net_transport FROM sys.dm_exec_connections WHERE session_id = @@SPID;

You can force a client connection to use a specific protocol by prefixing the Server name in the connection string with one of these modifiers:

• TCP: tcp:
• Multiprotocol = rpc:
• Shared Memory = lpc:

e.g. Force connection to use the TCP protocol:

Server=tcp:MyServerName;Database=MyDB;Trusted_Connection=True;

In addition, you can force the client connection to use the Shared Memory protocol by using (local) as the server name. You can also use localhost or a period (.) e.g.:

Server=(local);Database=AdventureWorks;Trusted_Connection=True;

https://support.microsoft.com/en-au/help/313295/how-to-use-the-server-name-parameter-in-a-connection-string-to-specify

New to SQL Server Manager Studio (SSMS) 17.3 is the XE Profiler. This is Profiler-like functionality built-in to SSMS:

SSMS 17.3 has Profiler built-in

Just double-click either of the two entries to create a live trace window (built on the SSMS XE “Watch Live Data” functionality).  The event sessions that will be created are named:

• Standard:  QuickSessionStandard
• TSQL:        QuickSessionTSQL

A quick and easy SSAS optimisation: turn off flight recorder:

SQL Server Analysis Services Flight Recorder provides a mechanism to record server activity into a short-term log. Information captured by Flight Recorder can be helpful for troubleshooting specific issues, however the load placed on the server when capturing the snapshots and trace events can have a small impact on overall performance.  For optimal performance the flight recorder should be disabled unless attempting to capture diagnostic information relevant to troubleshooting a specific problem.

https://support.microsoft.com/en-au/help/2128005/flight-recorder-eanbled-for-sql-server-analysis-services

http://byobi.com/2016/01/ever-wondered-whats-captured-in-the-ssas-flight-recorder/

If you are running a SQL Server version prior to SQL Server 2016, and you have a query whose plan just doesn’t seem right and you can’t explain it, try running it with trace flag 4199

SELECT SomeColum
FROM SomeTable
OPTION(QUERYTRACEON 4199)

It enables all the query optimiser hot fixes present in your applied SP and CU version.
Many DBAs enable this trace flag globally (at the instance level).
SQL Server 2016 will automatically enable all prior version query optimiser hot fixes.

SQL Server query optimizer hotfix trace flag 4199 servicing model
SQL Server 2016: The Death of the Trace Flag

Bob Ward’s post has some interesting stuff in it: