Transact SQL :: Sessions Need To Have UPDLOCK To Avoid Deadlocks
Nov 21, 2015
The benifit of UPDLOCK is that it avoids deadlock in case both sessions run the below query at the same time.The table has clustered index on ID column
----session 1 --------
begin transaction
select * from a1
update a1
set id = 22
where id = 2
----session 2 --------
begin transaction
select * from a1
update a1
set id = 22
where id = 2
Now to avoid deadlock in the above scenario we should use (UPDLOCK) hint in the select statement.Now my question is that deadlock will be avoided in this case when both the sessions use UPDLOCK hint. If only one session uses UPDLOCk and other does not then there will be deadlock .For example session 1 uses UPDLOCK hint this will hold the U lock on the row, but the session 2 does not use this hint and apply shared lock on the same row. Now there will be deadlock when session 1 tries to update the record and is blocked by shared locks of session 2. same will be the case with session 2 and both will wait for each other and hence dead lock.so what steps can be taken to avoid deadlocks in this case. I do not want to use Snapshot isolation.
I am conducting stress testing for my website and keep getting deadlocks with the following message when one process is adding about 100 records per second and another process is trying to access the data:
Transaction (Process ID 499) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
What do I need to do in my stored procedures to avoid this? I only have ONE stored prcoedure that locks a row while incrementing an ID value. I am not doing any other locks, so is this a SQL Server system lock?
I'm a web developer. our system uses sql server 2012 since it was put in an environment production, what happened one year ago, but only now we are facing a disturbing problem. what happens it's that, when 30 users try to do the same operation in the database, we are getting deadlock status from the db in a few time. we did put this system in production one year ago and now we are facing this kind of problem.
We know that in other dbms using an optimistic lock solves the problem, but it's not our case, 'cause the users are not doing the same operation in a row.
We develop our system in java ee and our db is sql server 2012. These operations might be done on our api.
I am not sure if i am looking correctly at the deadlocks but i see deadlocks between two select statements.These statements are being run through an application. Below is the table schema from where the select is being performed
CREATE TABLE [dbo].[CMS_LOCKS7]( [PARENTID] [int] NOT NU, Â --we have a non clustered index on this column [CHILDID] [int] NOT NULL, --we have a non clustered index on this column [ISMEMBER] [int] NOT NULL, -- we have a non clustered index on this column [ORDINAL] [int] NULL,-- we have a non clustered index on this column
I am working on an app that getting quite a few deadlocks due to delete statements. Â I have turned on the sql trace flags and pulled the offending delete statements out of the ERRORLOG and trying to mesh those up with the indexes defined on the table, etc. looking to see if there is anything that can be done strictly from the db side (no app code change) to reduce/eliminate these deadlocks. Â I have ran some tests/played around with RCSI and even disabling lock escalation but neither have improved my results.
What I have done is to search the errorlog file for DELETE FROM Tablename, output those matching lines, then sort of normalize the literal values to # or XYZ, open in Notepad++, removed trailing whitespace + dups and sort to come up with these results for the unique list of offending T-SQL statements (a LOT easier to read in text editor so sending screen cap. Â
I am doing some audit and i  have below query, how can i get rid of duplicates from the below query any T SQL to get rid of duplicates...
I am using SP_Who2 and sql server  Audit for auditing all data happening on sql server databases  and dumping them to tables  Audit_DBAudit  abd Audit_sp_who2  and from then i am trying to get data which is not repeating/duplicate ...  SELECT A.ProgramName ,a.HostName,[Server_principal_name],[Server_instance_name],[Database_name],[Object_name],F.Statement FROM Audit_DBAudit as F  Join [Audit_sp_who2] AS a on LTRIM(RTRIM(F.server_principal_name))=LTRIM(RTRIM(A.Login))
Begin Truncate table A Insert into A (Col1, Col2, Col3... ) Select Value1, Value2, Value3... From Table B End
The insert operation query takes approximately 3.5 minutes to execute. What's occurring is the Table is immediately truncated, and there are no rows in the table for those 3.5 minutes.
How can I avoid having this gap - where there are no rows in the table for that period of time during the job execution ? The table could be locked, but that doesn't seem like the best solution.
Got a query taking too much time because of lack of cross columns MAX/MIN functions. Consider a similar example where a View is required to reflect distribution of Water among different towns each having four different levels of distribution reservoir tanks of different sizes:In this case the basic table has columns like:
Now suppose I need a query to distribute QuantityPurchased in the Four additional Columns computed on the basis depending on the sizes declared in the last four fields,in the same order of preference.For example: I have to use IIFs to check: whether the quantity purchased is less than Tank_A if yes then Qty Purchased otherwise Tank_A_Size itself for Tank_A_Filled
then again IIF but this time to check:
Whether the quantity purchased less Tank_A_Filled (Which again needs to be calculated as above) is less than Tank_B if yes then Tank_A_Filled (Which again needs to be calculated as above) otherwise Tank_B_Size itself for Tank_B_Filled
There are 3 tables Property , PropertyExternalReference , PropertyAssesmentValuation which are common for 60 business rule
SELECT   PE.PropertyExternalReferenceValue  [BAReferenceNumber] , PA.DescriptionCode   [PSDCode] , PV.ValuationEffectiveDate   [EffectiveDate] , PV.PropertyListAlterationDate   [ListAlterationDate]
[code]....
Can we push the data for the above query in a physical table and create index to make the query fast rather than using the same set  tables multiple timesÂ
connection 1. one does select max(grp) from orv and one does select max(grp) from orh. orh is the historical file from orv. We did this to know which is the greather grp between these 2 files. After having did this, we add 1 at grp field. we insert into orv the record max(grp) + 1
connection 2. an other application could insert at the same time record in this table orv with same parameters.
my problem is the following. I need to block record in orv table either on the select ( connection 1) or Insert ( connection 2) to avoid having select max(grp) + 1 on orv at connection 1 and Insert a record into orv at connection 2. I believe I need to use HOLDLOCK, UPDLOCK. but I have not the habitude to use them.
Can I do this ? connection 1 select max(grp) from orv WITH HOLDLOCK connection 2 what should I use to avoid lock when I need to insert into orv. ?
Is there anything I can do from the Enterprise Manager console or fromwithin a JDBC connection to achieve the same effect as WITH(UPDLOCK)?Yes, I could change all of my SQL statements to include the lock... butisn't there any way to set or tweak something in SQL Server so that I won'thave to hack a lot of code* to make things concurrent? Perhaps a way to setUPDLOCK as the default behaviour for the server, or schema, or table, orsomething?Jerry H.* == The existing SQL has to remain as generic as possible so that it can beimplemented for four other databases.
Hi all,Is this legal ?SELECT a.col1,b.col2,c.col3FROM tab1 a WITH (UPDLOCK) , tab2 b, tab3 cWHERE a.col1 = b.col1and b.col2 = c.col1WIll the above cause a UPDLOCK on tab1 and not tab2 and tab3?COmments,thoughts,criticisms?I have a problem with a query that performs a multi-table jointo get column values and then one of the tables in the join isbeing updated. I am getting DEADLOCKs and was wondering if I couldtry and reduce that.Also how can I find out what locks are in effect for a certainquery..Is it syslocks or are there any other tables..?DrD
I've got a SELECT WITH (UPDLOCK, ROWLOCK) WHERE followed by an UPDATE WHERE statement. The results of the SELECT statement are deserialized in C# and updates are made to the deserialized object. Then the object is serialized back into the table with the UPDATE statement. I've got this code running within a transaction scope with the ReadCommited isolation level.
My service receives requests to update data and the requests can come in on different threads. What I'm seeing, is that once in a while, the log messages from my application indicate that two different threads are able to issue the above SELECT statement and both are receiving results. This is a problem since the thread that issues the last UPDATE will overwrite the changes made by the first. Each thread has its own connection and transaction scope.
I've researched all over the place and have tried a few different things, but all things point to the fact that query hints are just hints and that SQL may or may not pay attention to them. If that's the case, how am I suppose to perform a SELECT with the intention of updating so that no one else can do the same? I haven't tried table level locking, but I'd really like to avoid that if possible.
This article instructed me on how to process rows from a table used as a data queue for multiple processes.
http://www.mssqltips.com/tip.asp?tip=1257
I tested this against the AdventureWorks DB (SQL 2005) and multiple SQL connections inside of Sql Mgmt. Studio).
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows --COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) --skips over locked rows
COMMIT TRANSACTION
This works like I want where connection 2 skips over the locked row from connection 1 and gets the next available record from the table / queue. However, when I add ORDER BY tsql to each sql statement, connection 2 is now blocked waiting for Connection 1 to commit. (This is not what I want)
Connection1:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate
--COMMIT TRANSACTION
Connection2:
BEGIN TRANSACTION
SELECT TOP 1 * FROM Production.WorkOrder WITH (updlock, readpast) order by DueDate --is blocked until connection 1 commits transaction
COMMIT TRANSACTION
How do I prevent blocking when using these locking hints with ORDER BY?
Hi, Here is my code on how i connect to my database Dim rst As New ADODB.Recordset Dim conn As New ADODB.Connection Dim vresponse As String ' On Error GoTo err_proc Try conn.Open(GetConn(getconnid)) Select Case getmode Case 0 'execute then return first field rst = conn.Execute(getsql) If rst.EOF = False And rst.BOF = False Then Try vresponse = IIf(IsDBNull(rst.Fields.Item(0).Value), "", rst.Fields.Item(0).Value) ' vresponse = rst.Fields.Count Catch ex As Exception vresponse = "Error :" + ex.Message End Try End If Case 1 'execute only If bTransactional = True Then conn.BeginTrans() End If conn.Execute(getsql) vresponse = "OK" If bTransactional = True Then conn.CommitTrans() End If End Select Return vresponse.Trim * line 1) rst = Nothing conn = Nothing Exit Function
supposed to be *line 1) terminates the connection/session form SQL server. But when i check to the SQL Query Analyzer, there is still some connections related to this command. So when i run again this commands, it creates another connection. How can i terminate/end my sessions in SQL.
Hi all! First of all, thanks to those who gave me suggestions to use sql-dmo to generate sql scripts of a database. I've found it extremely useful!
Here's my new problem. I have VB code that connects to a database, extracts the schema and generates the sql. After some work with this script, I have some new scripts to alter the database and I have tried running these scripts in a separate project with the ExecuteImmediate method of the Database object, which works well.
However, when I put this code into the first project, to reconnect to the database and execute the batch command, I get SQL-DMO error -2147199229 (80045203) ...whatever that means..
We need a small suggestion regarding releasing the resources utilized before closing the session we established with the SQL CE database. To the best of our knowledge we are releasing the resources properly but still some how some resources get locked and we were not able to open a new session after closing the existing session.
Are there any functions or methods available to identify the existing resources, rowsets and other components who have connection with the existing session, kindly help us in this regard since we struck up mainly with this issue. We work with EVC++ 3.0 and SQL CE 2.0
hi all i am using .net web application with sql server as my database, i want to login by authentication from my database which i ave done but now i want to add session but dont know the code so if anyone can help me with stepwise process to assign username in the seeion also to create and destroy the session.urgent help required
hi is it possible to insert a session into a database E.G. i'm sure this code is fine but i duno why its not inserting the session into the database the form parameter is going in fine but the session aian't UserName.Text = Session("User")<asp:sqldatasource id="SqlDataSource1" runat="server" selectcommand="SELECT Party.Party FROM Party" insertcommand="INSERT INTO Vote(UserName,Vote) VALUES (User,Party)" ConnectionString="<%$ ConnectionStrings:VotingConnectionString %>" ProviderName="<%$ ConnectionStrings:VotingConnectionString.ProviderName %>"> <InsertParameters> <asp:SessionParameter Name="User" Type="String" SessionField="User" /> <asp:FormParameter Name="Party" Type="String" FormField="PartyList" /> </InsertParameters> </asp:sqldatasource>
How can many users share the same .adp front end, just like it as if it was a .mdb file? The problem I've ran was the following...user A logs in, user B tries to use the same .adp front end, but gets a message that is already in use therefore can't get in. Thanks in advance!
I have a process that seems to leave many orphaned sessions over a period of time. The software is by a 3rd party vendor and they can't seem to fix it. It is safe to end the orphaned sessions and I do that on a regular basis. My questions is: What is the best way to do this via T-SQL?
I can select the orphaned sessions by using a simple query on the sys.dm_exec_sessions table. How do I then run a kill command for each session_id from that query?
I have a problem in controlling the report session. I created a Reporting Model using SQL reporting Services 2005 with Forms authentication on which I implemented the security Filter based on the function GetUserID() to report only against data that belong to the login User, and I deployed the Model. Using report Builder application I created a report that contain in the first column the user name (UserName) from entity €œUsers€?, and in the remaining columns data from other entities related to table users, I saved the report on the report server. I logged in into report manager with user €œUser1€? and I ran the report, the result was the same as expected (in the first column €œUser1€? appeared and in the remaining column other data related to this user appeared) every thing went good After that I logged in with the user €œUser2€? and I ran the report and here was the surprise the same data that appeared for "User1" appeared for "User2". but what was Expected is different data that belong to "User 2" After some research that says that this problem may be caused by a session issue (the session created for the first user who enters the report server will remain for the other users that enter after him), I reset IIS and I logged in with €œUser2€?, and I ran the report the correct data for €œUser2€? appeared So it may be a session issue.
My question is: Is there any way to control the session content and the session expiration? Please note I used all the solution provided in my research such as URL parameter rs:ClearSession = true, and the Report Execution Options in report manager but non of this helped me. I will be thankful for any one who could help me in this urgent issue.
I'm using SQL server 7 on Win NT. I have Access 97 as a front end, with linked tables though ODBC to SQL Server. Everytime I open a table in Access, a session appears when I type sp_who2. I close that table in Access, but I when I type sp_who2 the table session is still present. Does anyone know a cause for this?
I am researching why sometimes when we close are queries and tables in Access we have sessions in SQL server that becomes orphans/ghost. I try to kill the session but can't, so therefore I have to recycle the database.
I just have a simple question on font dependencies in reference to deployed reports. In my company, we run citrix presentation servers feeding terminal sessions out to users in remote areas.
My question is, in a terminal session, do the fonts used in the reports need to be installed on the users' local machine (who is connecting via terminal session) or is it enough to just have it on the servers feeding out the terminal session?
For example, we create a report with Arial Narrow font. Our servers hosting citrix presentation server did not have this font installed, so we installed this font on the servers (thus they're displaying correctly). Obviously the server hosting our reporting services has the font. Now a user connects to the server, is granted a terminal session, launches reporting services, report is generated with the correct font displayed, and finally prints the report.
Will the report print in Arial Narrow if the users' local machine doesn't have this font install? I remember reading somewhere that the fonts do not embed, hence the reason for installing the font on our citrix servers.
I realize this is kinda out of the scope of this forum, but perhaps someone on here uses terminal services and can answer this for me. I do plan to test this out when I get home tonight. I'd test it right now, but my computer at home isn't on therefore I can't remote home (plus wake-on-lan isn't configured) to do an actual test. Just thought I'd get some insights from other people.
I have been looking at the new DMV's prefixed with dm_exec_....and found a limitation with them.
Books online says sysprocesses is replaced with sys.dm_exec_connections, sys.dm_exec_requests and sys.dm_exec_sessions. The problem I came accross is identifying any sessions connected to a specific database which were idle. This is the sort of thing you need to know if you tried to restore a database and it says the database is in use.
Is there a way to find the max number of sessions that were on a sql server since its last restart? I know how to get how many total connections there were since last restart, and the current number of sessions, but not the max number of sessions that were running since last restart. Also, opinion on the optinum number of allowable sessions, or a good way to figure out the balance?
So I've been monitoring long-running transactions on a SQL Server that hosts a couple of vendor-supplied databases that look after our factory.Today I noticed a pair that have confused my Excel spreadsheet (that I've been using to analyze these transactions).So here's the weird thing that I spotted. Given this query:
SELECT p.spid, p.login_time, at.transaction_begin_time, datediff(second, p.login_time, at.transaction_begin_time) as [difference] FROM sys.sysprocesses AS p INNER JOIN sys.dm_tran_session_transactions AS st ON st.session_id = p.spid INNER JOIN sys.dm_tran_active_transactions AS at ON st.transaction_id = at.transaction_id
[code]....
I had a look in the event log on the server, which had just been rebooted at around that time. It seems that the clock got changed on boot-up, with the size of it quite surprising. This meant that these processes were able to start their transactions *before* they logged on. Hopefully this doesn't cause any other weird problems.So I've requested an investigation about time synchronization on our virtualization hosts... and in the mean time, have set the SQL Server services to 'delayed start'.
