SQL Server Row Locking
Jun 28, 2001
I have a table X with 61390 rows on it. IT is a crucial table which is being read and updated constantly. If I create a clustered index on the Primary Key (identity column) and run UPDATE x SET c1 = 1234 where PKCOL = 4321 the best lock I can get is a table Lock. If I create a compound non-clustered index on C1 and PKCOL the best lock I can get is a Page Lock. PAge Lock is OK but as this table is in High demand I want a row lock so others can carry on referenceing other parts of the table. WHy does it take a page lock and not a Row lock?
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Jul 7, 1999
Hi,
We are becoming increasingly more involved with SQL Server 7.0 development.
Can someone show me a good example of ROW LOCKING with exclusive and share
modes?
If I am starting a transaction with a SELECT and later an UPDATE, what is
the best way to handle locking?
Thank you for any help on this issue.
Steve
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Mar 6, 2007
is there a way of locking db on server. i am doing a overtime and pay system but there is a few members of IT staff that are very nosey and this is senstive information and i dont want them looking at the tables on the server can these be locked for only me to view
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Mar 22, 2007
Hello,
I'm trying to determine if a row in a table is locked. First, I issue a lock on some rows. Then, I query the syslockinfo table to see which rows are locked. It tells me which rows are locked, but it returns a hashed resource value that, I guess, is somehow related to the key. How can I un-hash the value? Or, how can I hash my own key so that I can compare it with the hashed value? I have tried using the HashBytes function, but I don't know what is actually being hashed when the row is locked.
For example:
begin transaction
select * from test with (rowlock, updlock)
select * from master..syslockinfo
where rsc_objid = (select id from sysobjects where name = 'test') and req_mode = 4
returns:
rsc_text = (010086470766); rsc_bin = 0x000708001374FC020100010086470766
Thanks.
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Apr 23, 2007
Hi
I have a setting where two Web Servers access the same SQL Server database. To gaurantee consistent data writes and reads I need to lock part of the database in special conditions.
I know exactly when I need particular tables of the database to be locked, but I am in doubt of how to do it. Does SQL Server 2005 have any mechanism for providing locks gauranteed to free the lock if one of the web servers crash - or if SQL Server itself crashes?
/Bezbos
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Feb 18, 2005
Currently I am working on asp.net Intranet system.I need some suggestion on records locking for Sqlserver & ASP.net.
I want to prevent two user to open the same record for modify.Means if some one has open one record (id=xxxxx) for modify then others should not be able to open same same record (id=xxxxx) for modify .otherwise if both user will open/update same record then information in database will not be updated correctly.
Any idea how we can do the record locking so that not two users can open same record(id=xxxxx) for modify.
Thanks in Advance
Arvind
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Feb 28, 2006
Hi,
How can i handle record locking in sql server?
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Jan 5, 2004
In the application I'm working on, I need to be able to use different locks on my records during certain transactions. I need to know how to do this programmatically from within VB.net. If someone can show me an example of how to do this or show me where I could find some, I'd appreciate that.
Thanks.
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Jul 23, 2005
Hi All,According to my observation using SP_WHO2 in my database, some INSERTstatements are getting blocked by SELECT statements. Though theblockingSELECT statement is having ReadPast hint, i think, it will only readpastlocked resources but will not guarantee the select statement itself notblocking other statements(in my case Insert). According to my knowledgeandinformation, select statements take shared locks but why then thesestatements are blocking insert statements?Can there be any other solution other than using NoLock hint as thishintmake sure no shared locks are issued but it can read uncommited data.Need help urgently.ThanksRitesh
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Dec 8, 2006
How to avoid table locks during simultaneous addition, deletion and updates of 50,000 records or more. I am using SQL Server 2005 interfacing with Java.
Thanks,
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Mar 27, 2007
Hi...
i hv a database (sql server 2000) where i got locking on many tables and my application was down.
I restarted the sql server and the application was fine but after five minutes the same locking issue started happening. I did a index rebuild the next time on all indexes and everything was fine.But i cannot relate how locking occured and why it was not after index rebuild.Can anyone shed some light on this or anyone had similar experience... cos i cannot figure out a way on this.
Thanks in advance
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Jan 29, 2008
Hi pardon my ignorance but I wonder if someone could answer a few questions for me.
I am writing a program which will be used by perhaps upto 100 users at a time. The program sits on any number of PCs and loads user specific data to a given PC according to who has logged on to windows on that PC.
A number of data items loaded from the user table have to be unique as they are usernames for other systems that my program simplifies access to.
So when a user logs on to my program for the first time a row is created for them in the user table (indexed by a GUID and their unique network name). The other unique fields are left blank and the user is given an opportunity to fill these details in.
Before writing these details to the user's row in the 'users table' the program loads the whole user table down and checks that these items are unique before committing them to that user's row in the table.
The problem of course is that if between the program downloading the user table into a local datatable, checking the values are unique and then actually writing them someone else writes the same data into their row then 2 users end up with the same data - which shouldn't be allowed. i.e. 2 users can't have the same user name for the other software.
How can I solve this problem with locking? Once the user table is downloaded and in a locel datatable presumably the table is no longer locked so another user could write data to the table.
I acutally think this is going to be a pretty rare occourance but I still want to try to cover all eventualities.
I suspect the problem is the way my program is going about the checking.
Should I use an SQL insert statement like??
If exists(SELECT username from users where username=@username)
BEGIN
RAISEERROR("Username already exists")
END
ELSE
BEGIN
INSERT etc
If so I guess this will simplify my code. Is this the correct thing to do? And then just trap the errors that arise if a duplicate does arise?
Also some more general questions.
1)I presume 2 users simultaneously looking up data from 2 different rows in a table doesn't lock the table so one search fails? I use the code below having set up a command to run a stored procedure to search for a user by their network name.
Dim lclRowRet As SqlDataReader
lclRowRet = LoadUserCommand.ExecuteReader(CommandBehavior.SingleRow)
lclRowRet.Read()
2) I presume writing data to my user table a row at a time will also not cause a lock. I create a command object with all the row values in and then do a command.executenonquery()
As a rule I close all my connections as soon as I'm done with them.
Many thanks for your help in advance.
nik
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May 9, 2006
I'm running a website on IIS 6.0 w. ASP.Net 2.0 and SQL Server Express 2005 via the native client. The connection string is fairly standard:
<add name="SiteSqlServer" connectionString="Data Source=.SQLEXPRESS;AttachDbFilename=c:DotNetNukeApp_DataASPNETDB.MDF;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
I find that after the website has been running for a while I can no longer open the database using SQL Server Management Studio Express (I get an error indicating that the physical file has been locked). Even if I shutdown and restart both IIS and SQL Server, it remains locked and can only be opened once I find and "End Process" all the sqlservr.exe instances from the Task Manager.
Is this a known issue? Any way to find out what is locking the database, or any specific configuration to check?
thanks
Steve
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Apr 22, 2015
We have one table.We have updated the status for one column to 1 and we did not committed the transaction. Can we do an another update on another row.
In below example i am updating GEO_D and transaction is not committed. Now my requirement is we have to update other records (not Geo_D). If try to update GEo_D it should wait.
IF OBJECT_ID('TEMPDB..##TEMP_STSTUS') IS NOT NULL
DROP TABLE ##TEMP_STSTUS
CREATE TABLE ##TEMP_STSTUS
(
ID INT IDENTITY(1,1)
,NAME VARCHAR(10)
,STSTUS VARCHAR(10)
)
INSERT INTO ##TEMP_STSTUS SELECT 'GEO_D','0'
[Code] ....
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Nov 10, 2003
A fellow developer of mine has created a ASP.Net application that executes some fairly complex stored procedures. This application is for all intensive purposes a queue and 3 or 4 people work on processing items in a FIFO type environment. There is logic in the Stored procedures to make sure each worker get a unique entry using a series of query hints.
Well what we are seeing is if these works are moving at a rapid pace and we execute an sp_who2 on the sql server there are entries that that seems to be hanging there and REMAINING there even after a browser is closed or the disposed method has been called on the connection object. Has anyone else experienced something similar to this with an ASP.Net application used by mutiple people?
My inclination is to blame the design of the application, but before I do that and step on my co-workers toes I thought I would throw this out to the group.
Thanks in advance for your input.
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Jan 5, 2001
I'm running SQL Server 7.0. I have a DB running with 6.5 compatibility mode.
Do INSERT, UPDATE or DELETE queries use row level locking in this DB ?
(I know if I set the db compatibility mode to 7.0 row level locking will be enabled)
Thanks in advance for your help.
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Dec 23, 2004
Hi,
Our app has been distributed on more then 300 different sites.
On one of the sites we get the error "Could not continue scan with NOLOCK due to data movement" indicating that the query optimizer takes a NOLOCK for our select statement ( has been opened with adOpenDynamic, adLockOptimistic ).
It's no option to change the source, we have to solve this without touching the code.
Is there any way to tweak the query optimizer so that our app works correctly?
I know that there will be a reduction of performance but it's our only choose.
thnx in advance,
adOpenDynamic, adLockOptimistic
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Nov 28, 2005
We are running a 3rd party ETL tool to populate a denormailized version of a production database for reports. Everything works fine 95% of the time. However there is a semi-rare occurence of the ETL tool hanging up. The norm is for the tool to take about 5 times longer than usual, but it still works. Over the weekend however it through an error saying:
The SQL Server cannot obtain a LOCK resource at this time. Rerun your statement when there are fewer active users or ask the system administrator to check the SQL Server lock and memory configuration.
The reports are run through Crystal using stored procs and are all basically select statements
So my question(s) are the following:
1. What kind of lock would a report put on a table (select statement)
2. Would it make sense to change stored procs to use WITH NOLOCK?
3. Or is something else going on?
Your thoughts would be greatly appreciated.
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Jul 20, 2005
Need some information regarding SQL Server locking.Requirement is to run SQL Statements for reports (read-only) that willnot lock-out other people trying to update (write lock). For this, wetried the following to make the db connection not deny write locks(our report code will not have a read-only lock).ADODB.ConnectionObj.Mode =adModeShareDenyNoneBut this made our connection bumped whenever someone tried to update.Tried enabling dirty reads by doing:ADODB.ConnectionObj.IsolationLevel =adXactBrowseEven this made our connection bumped whenever someone tried to update.Is there a way to achieve what is needed without having a seperatedatabase for reports?
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Nov 9, 2007
Hi ,
I would like to get your advice in an issue that I am facing regarding merge replication.
The flow is like:
1) User enter his login name and password.
2) Host_name is set as the login name that the user enters.
3) Based on the HOST_NAME property after filtering user gets the records relevent only to him
(Differnet subscriber may use same mobile device).
4) He make some changes in the local sdf according to the business logic.
5) The application Syncs with server on the next login session.
My issue is when I am trying to run the application in emulator exactly at the sdf updating part the application terminates.
Error mess: Connection to Remote Device has been lost.....
If I execute the same sql insert query it works om the local sdf and master database.
Emulator used where Pocket PC 2003 SE and Windows Mobile 6 classic emulator.
I have installed 1) Visual Studio 2005 SP 1 2) net compact framework SP2.
When I comment all the code related to Sync ,application works witout any issue.
And the same application works in my "I mate kjam".
The code that I use is given below:
==========================================================================
public void Sync(string hostname, int newsub) // Parameters for HOSTNAME and flag to denote new user or existing //user.
{
SqlCeReplication repl = new SqlCeReplication();
repl.InternetUrl = @"http://231.000.000.211/Merge/sqlcesa30.dll";
repl.Publisher = @"SERVER";
repl.PublisherDatabase = @"Merge";
repl.PublisherSecurityMode = SecurityType.DBAuthentication;
repl.PublisherLogin = @"sa";
repl.PublisherPassword = @"password";
repl.Publication = @"Merge";
repl.Subscriber = @"MergeSub";
repl.HostName = hostname;
repl.SubscriberConnectionString = @"Data Source=""Program FilesMerge.sdf"";Max Database Size=128;Default Lock Escalation =100;";
try
{
if (newsub == 0)
{
if (File.Exists(@"Program FilesMerge.sdf"))
{
File.Delete(@"Program FilesMerge.sdf");
}
repl.AddSubscription(AddOption.CreateDatabase);
repl.Synchronize();
repl.Dispose();
MessageBox.Show("newuser sync Done");
}
else
{
if (!File.Exists(@"Program FilesMerge.sdf"))
{
repl.AddSubscription(AddOption.CreateDatabase);
repl.Synchronize();
repl.Dispose();
MessageBox.Show("FirstSync Done");
}
else
{
repl.Synchronize();
repl.Dispose();
MessageBox.Show("SameuserSync Done");
}
}
=================================================================================
Please advise......
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Apr 6, 2001
Every time I execute DBCC DBREINDEX (Table_Name, '',0)WITH NO_INFOMSGS the server hangs. No error messages in windows 2000 logs or in the SQL 7.0 logs.
The table is about 2 gig in size and the index is a clustered index on two fields.
The server has 1 gig of memory and the cache hit ratio, and cache flushes both look good. Any ideas? Any help would be greatly appreciated.
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May 4, 2015
I have a main table called Stock for example.
One process ( a service ) inserts data into this table , as well as updates certain fields of the table periodically.
Another process ( SQL Job ) updates the table with certain defaults and rules that are unknown to the service - to deal with some calculations and removal of null values where we can estimate the values etc.
These 2 processes have started to deadlock each other horribly.
The SQL Job calls one stored procedure that has around 10 statements in it. This stored proc runs every minute. Most of them are of the form below - the idea being that once this has corrected the data - the update will not affect these rows again. I guess there are read locks on the selecting part of this query - but usually it updates 0 rows - so I am wondering if there are still locks taken ?
UPDATE s
SET equivQty = Qty * ISNULL(p.Factor,4.5) / 4.5
FROM Stock s
LEFT OUTER JOIN Pack p
on s.Product = p.ProductId
AND s.Pack = p.PackId
WHERE ISNULL(equivQty,0) <> Qty * ISNULL(p.Factor,4.5) / 4.5
The deadlocks are always between these statements from the stored procedure - and the service updating rows. I can't really see how the deadlocks occur but they do.
Another suggestion has been to try and use an exists before the update as below
IF EXISTS( SELECT based on above criteria )
( UPDATE as before )
Does this reduce the locking at all ? I don't know how to test the theory - i added this code to some of the statements, and it didn't seem to make much difference ?
Is there a way to make a process ( in my case the stored procedure ) - give up if it can't aquire the locks rather than being deadlocked - which leads to job failures and emails etc ?
We are currently trying to filter down the data that is updated to be only the last few months - to reduce the amount of rows even analyzed - as the deadlocking does seem to be impacted by the number of rows in the tables.
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Jul 16, 2015
I am using following sql to extract locking information in database. It only work on current selected database, how can I tune to work on all databases and not only currently selected?
SELECT DISTINCT
ES.login_name AS LoginName,
L.request_session_id AS BlockedBy_SPID,
DATEDIFF(second,At.Transaction_begin_time, GETDATE()) AS Duration_Sec,
DB_NAME(L.resource_database_id) AS DatabaseName,
[Code] ....
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Sep 18, 2015
I have two tables for insertion in one transaction scope. Table one have 10 rows. After first table insert statement (not yet committed) if I run select on first table from other session, it holds table until my insert is committed or rolled back and from (SSMS), it display 10 rows and then wait for transaction scope till finished. My question is do I need to use no lock hint in this situation. Or there is something wrong with isolation level. One saying that in this situation table should not hols select while insert is in transaction scope.
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Feb 1, 2008
Hi All -
My Set up:
Server A - Oracle 10g Database
Server B - SQL2005
Client PC - Sql Express
Server A holds all data. I am using a linked server to connect server A and B. I use a set of stored procedures containing the openquery() syntax to get data from Server A to Server B. These stored procedures run every 20 minutes. I then create a publisher on Server B. I subscribe from the client PC to publisher to get data down from Server B to client(Download only subscription).
When I fire up the stored procedures and attempt to replicate, everything works fine. It appears after about 4-5 hours of the stored procedures running replication begins to hang more and and more until eventually it hangs for about 10 minutes and I recieve the following error:
Command attempted:
{call sp_MSreleasemakegenerationapplock}
Error messages:
The merge process was unable to create a new generation at the 'Publisher'. Troubleshoot by restarting the synchronization with verbose history logging and specify an output file to which to write. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200994)
I'm not sure if there is an error with openquery() locking? There is some locking activity going on with the TempDB and and Server B database. I've also come across some threads talking about the agent profiles. I'm very new to replication and very confused by all of the options in the agent profiles. Any help would be greatly appreciated!
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Apr 2, 2015
I have a production DB that all of a sudden it seems that any and every insert causes massive locks/blocks.
If I kill the offending spid anther spids pops up with the block/lock.!
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Nov 11, 2015
Is it possible to force row level locking in Sql server 2015 before inserting the data and release the same afterwords..find the code for which we would like to impliment the same
DECLARE @TravelAgentid Varchar(20)
DECLARE @Date DATETIME2(7)
DECLARE @InsDate DATETIME2(7)
set @TravelAgentid ='A101'
[code]....
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May 28, 2008
Hi everyone,
I have a question about SQL Server 2005. I have written an ASP.Net 2.0 Web Application and it is using SQL Server 2005 as Database.
In the last few days I noticed that the app is down sometimes. To analyze the problem I looked at the activity monitor in SQL Management Studio. I can see there approximately 170 processinfos.
I want to describe the column values of the process infos:
Process-ID: Unique ID and a red down-showing-arrow-icon
User: My UserDatabase: My DatabaseStatus: sleepingCommand: AWAITING COMMANDApplication: .Net SqlClient Data Provider
When I click Locks by Object, I can see the IDs of the Processinfos. Again I will show some colums:Type: DATABASERequirementtype: LOCKRequirementstate: GRANTOwnertype: SHARED_TRANSACTION_WORKSPACEDatabase: My Database
So my question is, does this mean, that i have locked the db? How are they handled? For example I have a windows service, which is doing checks in db every 10 seconds. I can see, that each check generates a new processinfo?
Is this usual, or am I doing something wrong?
Thnaks for help,Byeee
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Jul 9, 2001
When I run a select statement : select 'X' from table1 where c1 = condition locking on indexes behaves as expected
However if I run select 1 from table1 where c1 = condition locking on indexes goes wild locking pages and rows on indexes that are not even referenced in the query. Any ideas Why?
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Dec 29, 2000
Hello All,
I'm just migrating from oracle to SQL.Can anybody tell me that how effectively I can use Row level locking in SQL? If tow users are attemping to
Moify same record how i can deal it in Back end(SQL)?
Thanks in Advance.
Suchee
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Sep 25, 2000
currently im using NT 4 (SP 6a), Intel Pentium III 600 (DUal processor) and 1GB RAM.
the problem that i facing now is DEADLOCK. the lock type in my database is 'DB type', how can i change to 'KEY' type or 'TAB' type???
pls help me and thanx in advance... :)
from comel
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