Takes as Long as it Takes SQL, Break on Me, I have a DAC…

The DAC, what is it? It is the Dedicated Administrator Console. Basically it is a way to connect to your SQL Server when all the other connections are tied up. But it takes a little bit of pre-planning so that you can use it when things go bad with your SQL Server.  Let’s enable it so you can test using it and know that it is there in the future.


EXEC sp_configure 'remote admin connections', 1;
GO
RECONFIGURE
GO

I was always afraid to use the DAC because I thought I had to use the command line and I am terrible with cmd. But did you know, you can connect to it through Management Studio? Now I can feel right at home when I trouble shoot a sick server.  To connect to a server using the DAC put “admin:” in front of the name of the server like this:

DAC

I use my elevated windows login for this point, but you can use what ever sys admin account that you have.

There are a few words of caution. You can only have one connection to your DAC on each server at a time. So don’t try to connect Object explorer to it. I have SQLPrompt and noticed that my server would send an alert on Severity Error 20 because SQL Prompt was trying to connect at the same time and was failing. Just be aware that you might get an error, but if everything is correct you can look down at the connection at the bottom of the query window and see you are connected.  If someone else is using the DAC, you won’t be able to use the connection, so it is a good idea to always close it when you are done.

Kendra Little b|t has a fantastic post for Brent Ozar Unlimited about the DAC and most importantly to me, how to tell who is connected.  This is the code that she wrote to help identify who is connected:


SELECT
CASE
WHEN ses.session_id= @@SPID THEN 'It''s me! '
ELSE '' END
+ coalesce(ses.login_name,'???') as WhosGotTheDAC,
ses.session_id,
ses.login_time,
ses.status,
ses.original_login_name
from sys.endpoints as en
join sys.dm_exec_sessions ses on
en.endpoint_id=ses.endpoint_id
where en.name='Dedicated Admin Connection'

Now when SQL Server Breaks on you, there is a tool that prevents us from shattering like glass.

If Crazy = Genius, I’m rebuilding one partition at a time!

We have had an index job that has been failing for a while.  This is one of those things you really don’t want to clean up because no one is complaining, but you know you should.  I had heard that I could rebuild one partition at a time, but where to start?  Today, I worked my way through it, so here it is so that you can do it too.

First you need to find the biggest indexes, there is a good chance those are the ones that live on partitions. I am removing Primary Keys.


SELECT i.[name] AS IndexName
,SUM(ps.[used_page_count]) * 8 AS IndexSizeKB
FROM sys.dm_db_partition_stats AS ps
INNER JOIN sys.indexes AS i ON ps.[object_id] = i.[object_id]
AND ps.[index_id] = i.[index_id]
WHERE i.name NOT LIKE 'PK%'
GROUP BY i.[name]
ORDER BY IndexSizeKB DESC

The top ones are most likely the ones you want to focus on.  Next, we need to track down the partition function.


SELECT * FROM sys.partition_functions

Next we are going to figure out which partition we want to rebuild.


SELECT sprv.value AS [Value], sprv.boundary_id AS [ID]
FROM sys.partition_functions AS spf
INNER JOIN sys.partition_range_values sprv ON sprv.function_id = spf.function_id
WHERE (spf.name = N'NameOfFunctionFromPartitionFunctions')
ORDER BY [ID] ASC

Pick the number of the partition you want to rebuild.

Next use your index name from earlier.  You will also need the table name and the partition number.


ALTER INDEX [IndexName]
ON [dbo].[TableName]
REBUILD PARTITION = 3

This will rebuild just the partition that you requested.

Strip it down and remove the bad query plan

Today I got to play with some really bad queries. But the queries weren’t necessarily bad, it was more they had bad plans. I thought I had already blogged about it and tried to find my code. Alas, it wasn’t there so let’s strip it down on how you would remove a bad query plan. I am leaving out the trouble shooting part of how to determine if it is a bad plan because so much of it “depends”.
First you have to find the bad query plan.  Get a unique line from your query and paste it in the query below.

USE master;
GO

SELECT usecounts, cacheobjtype, objtype, text, plan_handle
FROM sys.dm_exec_cached_plans
CROSS APPLY sys.dm_exec_sql_text(plan_handle)
WHERE usecounts > 1
AND TEXT LIKE '%Unique part of query%' --put the unique part of the query here.
ORDER BY usecounts DESC;

Now, copy the plan handle and paste it over the plan handle that I have listed here:

SELECT * FROM sys.dm_exec_query_plan (0x060001004DE4D526F0BEA28F05000);

If you click on the query_plan link, you can see what the plan looks like.  After you have reviewed it and determined the plan is bad then you can paste your plan handle over the one below to remove it from the proc cache.

DBCC FREEPROCCACHE (0x060001004DE4D526F0BEA28F05000)

There you have it. Best of luck with your bad plans.

For one good, naughty little girl found a diamond…Object Explorer Details

It’s Christmas time again and time to listen to my FAVORITE Christmas song called Joel The Lump of Coal.
Just before Thanksgiving we had our SQLSaturday\Big Mountain Data event and I spoke! This is my third time speaking at this event and every year I regret speaking and feel like everyone would have been better in another session, every year that is until this one! I loved my session and I will actually be submitting it to PASS Summit this year. Keep your fingers crossed with me. It was on SQL Server Management Studio Tips and Tricks.

One of the tips that I was super surprised that many people didn’t know is the Object Explorer Details. It allows you to delete multiple objects at once, script out multiple objects at once and just do some really cool stuff. How do I access this magic you are asking? When in management studio, click on View>>Object Explorer Details.

 

ObjectExplorerDetails

Now you can have a diamond that will help you too!

She keeps her management studio error to minimal, Southern Style…

It is painful when you have been working on a tough query and you start to get an out of memory error.
“An error occurred while executing batch. Error message is: Exception of type ‘System.OutOfMemoryException’ was thrown”

What in the world? But it was working before! Why is this happening? Is it happening for everyone? Do I need to reboot the SQL Server?

This is a SQL Server Management Studio Error. Usually it means that you have filled up the local memory cache on your machine. Save all your queries and close Management Studio. Once you open it again you “should” be fine, but famous last words right? If that doesn’t work, just reboot. Nice clean memory and you can get back to playing with your super tough query.

What you gonna do? Memory, I’m coming for you!

Today I needed to quickly check 68 SQL Server Instances Min and Max memory settings. I didn’t have time to go through each one and I know I will need to do this again in the future. Thank goodness I have my Central Management Server configured with all those servers. I was able to connect to my main CMS server, and run this simple query that will tell me all my servers min and max memory setting:

SELECT ServerName, [Max], [Min]
FROM
(SELECT @@ServerName AS ServerName, LEFT(name,3) AS Memory, value
FROM sys.configurations
WHERE name like '%server memory%') AS SourceTable
PIVOT
(
MAX(Value)
FOR Memory IN ([Max], [Min])
) AS PivotTable;

Then, I also used this code from my last post but added a server name to it so I could see what memory was available on each server.

SELECT @@Servername,physical_memory_kb * 9.5367431640625E-7
FROM sys.dm_os_sys_info