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How to capture and execute queries in SQL Server

In this article we will see how to capture and execute queries by means of sys.dm_exec_requests in SQL Server

With SQL Server 2005 and above SQL Server provides Database Management Views that gives you straight entry to execute needs and operation practices. The subsequent query uses sys.dm_exec_request, sys.sysprocesses. We will also use traverse affect to find the query transcript from sys.dm_exec_sql_text and the effecting arrangement as of sys.dm_exec_query_plan.

As a DBA, it is compulsory to continue a judgment on your record and attendant too, more than ever all through the industry hour. SQL Server has given that very cooperative self-motivated administration View to assist in this condition. Self-motivated administration View is as follow:

  • sys.dm_exec_requests
  • sys.dm_exec_sessions

Listing 1: Sample showing execution plan of create view

 
		CREATE VIEW ITIsGoOn
		AS
SELECT
OBJ_NM(objectid) as ObjectName
,SUBSTRING(stateText.text, (statement_start_offset/2)+1,
((CASE statement_end_offset
WHEN -1 THEN DATALNTH(stateText.text)
ELSE statement_end_offset
END - statement_start_offset)/2) + 1) AS statement_text
	,DB_Name(database_id) as DatabaseName
	,req.cpu_time AS CPU_Time
	,DATEDIF(minte, last_reqst_strt_tm, getdt()) AS RuningMinte
	,req.Percnt_Complete
	,sess.HOST_NAME as RunningFrom
	,LEFT(CLIENT_INTERFACE_NAME, 25) AS RunningBy
	,sess.session_id AS SessionID
	,req.blocking_session_id AS BlockingWith
	,req.reads
	,req.writes
	,sess.[program_name]
	,sess.login_name
	,sess.status
	,sess.last_request_start_time
	,req.logical_reads
	 FROM
	sys.dm_exec_requests req
	INNER JOIN sys.dm_exec_sessions sess ON sess.session_id = req.session_id
	AND sess.is_user_process = 1
	CROSS APPLY
	sys.dm_exec_sql_text(sql_handle) AS stateText		

	

Now, whenever you are approximating, I wish to make out the grade whether whatever thing is overcrowding to query/queries or which query is being executed as of which point in time. How much part absolute by just execute one simple SELECT statement:

Listing 2: Sample showing execution plan for select

 
SELECT * FROM ITIsGoOn

Much instance we want to locate who are admitted in to SQL Server case with which tool. SQL Server generates this very function in sequence to us with following two DMVs.

  • sys.dm_exec_requests
  • sys.dm_exec_sessions

I have created VIEW in my SSMS Instance to imprison all these essential in turn.

Here is the TSQL script for the same:

Listing 3: Sample showing execution plan create view

 
CREATE VIEW HeisLogIn
AS
SELECT
ISNULL(sess.host_nm, '') as host_nm,
ISNULL(DB_NAME(req.database_id) , '')  as database_Nm,
ISNULL(sess.program_nm, '')   as ProgramNm,
ISNULL(sess.login_nm, '')  as login_nm,
ISNULL(CAST(req.start_time AS VARCHAR), '')  as start_time,
DATEDIF(MINUTE,ISNULL(req.start_time,GETDT()),GETDT())  as RuningMinte,
	req.Session_id
 
FROM
sys.dm_exec_requests req
INNER JOIN
sys.dm_exec_sessions sess
ON
req.session_id=sess.session_id
WHERE
--will eliminate all system processes
req.session_id >= 70
AND
sess.host_nm IS NOT NULL

On one occasion we create this VIEW in our SQL Server, you do not require to memorize compound query but to use only client affable given name “WhoisLogIn” with normal SELECT query similar to this:

Listing 4: Sample showing execution plan for select

 
		SELECT * FROM HeisLogIn
 

Note: I have on paper one, which was ruling at present consecutive process in SQL Server with the assist of above given two DMVs.

What is Rapid Vigor

It gives the impression of being at memory and central processing unit disputation for the matching times as hang around stats. We are expressly looking for high central processing unit handling, PLE drops, and changes to objective recollection. It is also acknowledged in the Operating System presentation counter situation.

Look for overcrowding in the previous hour, even at the same time since it would naturally show up in remain stats. You can evaluate this to preceding existence if desirable, predictable in the overcrowding position.

Give the impression of individual at the enormous queries that accomplished in the last few hours beside with the queries presently successively to see if whatever thing pops out. This is now a speedy momentary look, looking for conspicuous issues, and you can come across for information after receiving answers to the summarized questions. Accomplished queries are acknowledged in the Tracing conception and appreciative posts, and presently consecutive queries are predictable in the consecutive Processes place of duty.

Give the intuition of being at the queries reprocessed freshly to see if a new implementation sketch is taking unnecessary possessions. Acknowledged in the recent times Reprocessed source send.

Why sys.dm_exec_requests does not show my SPID?

sys.dm_exec_requests will take into custody any gathering that is vigorous at the moment in time you complete the DMV. In the impression of an unattached process, this should at a standstill demonstrate in the outcome from sys.dm_exec_requests nevertheless, exact in all times.

  • Instance (Requires Exploration mechanism)
  • Unfasten two SQL SERVER MANAGEMENT STUDIO query execution interface, so you have two dissimilar session IDs. In the opening session, implement the subsequent proclamation

Listing 5: Sample showing execution plan

 
tsql
SET TRANSCTON ISLATON LEBEL SERIALIZE  
BEGIN TRAN  
 UPDATE Purchase.PurchaseOrderHeadr SET SubTot = 90 WHERE PurchaseOrderID = 81225
--COMMIT
      

Note down the commented out COMMIT command. In this example, session ID 50 is executing this UPDATE on PurchaseOrderHeadr. On this position, we have an unattached operation. In attendance are a small number of behaviors we possibly will secure this. Put up the shutters the doubt porthole forceful SQL Server to revolve it back, KILLS the SPID, or COMMITS it. In this position of the open deal being missing and I, as a DBA, need to slay it so it is rolled back, I need to discover that session ID. Keep in mind, not anything can strike that PurchaseOrderID until this deal is handled. If you would like to confirm that, go to the second query windowpane and session ID #2 (mine is 58) and execute

Listing 6: Sample showing execution plan

 
tsql
select * from Purchase. Purchase OrderHeadr WHERE Purchase OrderID = 81225

I will observe the SELECT by no means finishes as it is living being blocked by session 57.

The primary object is to scuttle sys.dm_exec_requests. This is wherever the skill of sys.dm_exec_requests just becomes puzzling on its efficiency.

Listing 7: Sample showing execution plan

 
tsql
SELECT * FROM sys.dm_exec_requests where session_id = 57

The above consequence should show the active assembly but it does not. Give the impression of being furthers at the present at the columns those sys.dm_exec_requests consequences in.

Now, what would be cooperative is for sys.dm_exec_requests to within peak of truth job the system it implies, but that is not the in sequence. In the case, give the intuition of being at DBCC OPENTRAN to substantiate we have the open convention we visualize we do.

Listing 8: Sample showing output plan

 
tsql
dbcc opentran
Transaction information for database 'AdventWork12'
Oldest active transaction:
SPID (server process ID): 59
UID (user ID) : -1
Name : usr_trnsactn
LSN : (182:306065:1)
Start time : Oct 21 2013 9:02:35:547PM
SID : 0x0105000000000005160000003fad1462eb25782c07e53b2b4f510000

If DBCC generates error communication, get in touch with your system manager.

The result demonstrate us the open maneuver and in standard, our job is complete and we possibly will take care of this sitting. But what if others are open? Which one do we grip? What we really want to seem at are the DMVs sys.dm_tran_database_communication and sys.dm_tran_session_tranasactions. This can lead us further to use sys.dm_exec_conecton and sys.dm_exe_sql_txt to obtain the definite statements.

A unsophisticated appear at the two deal DMVs

Listing 9: Sample showing execution plan for select

 
tsql
select * from sys.dm_tran_database_transactions db_trans
   JOIN sys.dm_tran_session_transactions sessions
      ON db_trans.transaction_id = sessions.transaction_id
where database_id = 6
tsql
select 
    sessions.session_id,
    statements.text    
from sys.dm_tran_database_transactions db_trans
   JOIN sys.dm_tran_session_transactions sessions ON db_trans.transaction_id = sessions.transaction_id
   JOIN sys.dm_exec_connections conns ON conns.session_id = sessions.session_id
   CROSS APPLY sys.dm_exec_sql_text (conns.most_recent_sql_handle) AS statements
where database_id = 6

If you run this instance, do not overlook to COMMIT that declaration for session. This actually shows us that every DMV has a reason and that cause does not demonstrate us what we may think at era. Employ the authority all the DMVs have when they are wanted. More prominently, use them mutually and make sure, if one doesn’t consequence in what you believe it should, if one more DMV is more appropriate to the task at tender.



Website: www.techalpine.com Have 16 years of experience as a technical architect and software consultant in enterprise application and product development. Have interest in new technology and innovation area along with technical...

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