SSIS Task IsolationLevel Vs. NoLock
May 9, 2007What happens if a Data Flow Task has the IsolationLevel property set to "Serializable", but has a query in an OLEDB Source with "NoLock"?
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Lookup Task With NOLOCK
Mar 2, 2006I have an SSIS package that unpivots data - each row from the source becomes 20-24 rows in the destination db. In the dataflow it looks up some type-data IDs before inserting into the destination table. The whole process flies through the data at an incredible rate, however I find that the final commit on data insertion takes a very long time, and two of the lookup tasks remain yellow throughout. It appears that there may be a contention issue because the final table has FKs to those lookup tables.
In T-SQL it is possible to do SELECT..... WITH (NOLOCK), but when I modified the SQL statement of the lookup task by adding this clause, it caused an error "Incorrect syntax near the keywork 'with'."
Is there any way around this problem? THNX!
PhilSky
Transaction IsolationLevel Problem
Apr 28, 2005Hi all, I have an application, which requires several SQL activities, so I wrap them in a transaction:SqlConnection conn = new SqlConnection(connectionString);conn.Open();SqlTransaction tran = conn.BeginTransaction(IsolationLevel.ReadUncommitted); I use MS Application Block for Data Access to handle all SQL statements:SqlHelper.ExecuteNonQuery(tran, CommandType.Text, sql); I have following problems: When I debug this application from my local machine, in the middle of this transaction, I cannot use my Sql Query Analyzer to do anything against some tables used in this transaction, even though I set transaction's isolation level to read uncommitted. Until I finish my debugging, result will return from query analyzer.
Does ReadUncommitted supposes to allow other SQL operation against the same tables at the same time?
Thanks
SSIS Task Transfer SQL Server Objects Task And Default Constraints On Tables
Feb 21, 2008
I am using the "Transfer SQL Server Objects Task" to copy some tables from database A to database B including data.
The tables, primary key constraints, Foreign key, data and all transfers nicely except for "DEFAULT CONSTRAINTS" on the tables.
I have failed to find any option in the "Transfer SQL Server Objects Task" task to explicitly say "copy default constraints". So I guess logically it should happen automatically but it doesn't. I hope it is not a bug :-)
Any option anyone knows will help.
Thanks.
SSIS (Integration Services) Transfer SQL Server Objects Task: This Task Can Not Participate In A Transaction
Feb 1, 2007In short, does the €œTransfer SQL Server Objects Task€? support distributed transactions?
In trying to use a €œTransfer SQL Server Objects Task€? in a container using a transaction on the container. The task is set to support the transaction. It is setup to copy table data from several tables from a non-domain server (sql server 2000) to a domain-based server (sql server 2005). I get an error stating, €œThis task can not participate in a transaction€?.
I am wondering if it means exactly what it says €“ this task in SSIS can€™t participate at all. Or does it mean that it won€™t in this scenario for some reason. I attempted a simple copy of data from mssql 2005 to mssql 2005 (same server) and the task still failed). MSDTC appears to be running properly on my machine and such (I can do a simple distributed transaction across linked server to the 2000 server in Query Analyzer (QA)). Also, MSDTC appears to be working on both servers with distributed transaction query tests in QA.
Here€™s the error info€¦
SSIS package "Development BusinessContacts and Products Migration.dtsx" starting.
Information: 0x4001100A at Copy BusinessContacts Data: Starting distributed transaction for this container.
Error: 0xC002F319 at Copy BusinessContacts database table data 1, Transfer SQL Server Objects Task: This task can not participate in a transaction.
Task failed: Copy BusinessContacts database table data 1
Information: 0x4001100C at Copy BusinessContacts database table data 1: Aborting the current distributed transaction.
Information: 0x4001100C at Copy BusinessContacts Data: Aborting the current distributed transaction.
SSIS package "Development BusinessContacts and Products Migration.dtsx" finished: Failure.
The program '[4700] Development BusinessContacts and Products Migration.dtsx: DTS' has exited with code 0 (0x0).
New 2005 SSIS Task: File Properties Task
Nov 7, 2007A common issue that I run across with clients is they want only want to process a file if it's finished transmitting to the server. This SQL Server 2005 task reads the properties of a file and writes the values to a series of variables. For example, you can use this task to determine if the file is in use (still be uploaded or written to) and then conditionally run the Data Flow task to load the file if it's not being used. You can also use it to determine when the file was created in order to determine if it must be archived.
http://www.pragmaticworks.com/filepropertiestask.htm
How Do You Get A Reference To The Task Host In An SSIS Task
Feb 26, 2008I've created my own posting for this. The original post was here, I apologize: http://forums.microsoft.com/forums/ShowPost.aspx?PostID=2906512&SiteID=1
According to the poster it's not possible. But there has to be some way to do it? Reflection (don't know how)?
I need to get a reference to the task host in an SSIS Task component.
Basically the scenario is this:
I have a custom task I have created. However I would like to validate that the ExecValueVariable is infact a string variable during the validate event of the task. I know how to verify its a string variable. But I can't figure out how to read what the user selected (such as User::Myvariable). The only way I've been able to figure out how to do it, but it only works if you open my custom task UI.
What I did is this:
I've implemented IDtsTaskUI and during the initialize section I wrote:
Sub Initialize(ByVal taskHost As TaskHost, ByVal serviceProvider As IServiceProvider) Implements IDtsTaskUI.Initialize
' Store the TaskHost of the task.
Me.taskHostValue = taskHost
Dim myTask As CustomTask= CType(taskHost.InnerObject, CustomTask)
myTask.myTaskHost = taskHost
End Sub
My Task is named: CustomTask. I have a public variable in my task as follows:
Public NotInheritable Class CustomTask
Inherits Task
Implements IDTSComponentPersist
Public myTaskHost As TaskHost = Nothing
Therefore I pass back the taskhost value to the CustomTask class, and voila I have it.
Problem is, this only works if the custom task calls the initialize method, and this only happens when you open the custom editor.
I then do the validation in my CustomTask class and it works fine, but myTaskHost is null/nothing until you actually open the custom task UI
How do I solve this?
NOLOCK Or Not To NOLOCK
Mar 9, 2005I need some help to under stand when the right time is for NOLOCK. I work in a small dev group and NOLOCK seams to be a buzz word and others are throwing it in all over for no apparent reason.
I read the thing from http://www.sql-server-performance.com/ and I am sure that our web and SQL servers are about 100x over sized for the application. While are ASP.Net (VB) app may demonstrate some hesitation from time to time I am more inclined to blame poor VB.Net coding techniques before slow SQL. The point being the NOLOCK is being added to SELECTS that are not part of a transaction and were using the SQL data adapter to return datasets or single column values.
Also I am not even sure it’s being used correctly. The OLM has the example:
SELECT au_lname FROM authors WITH (NOLOCK)
However I am seeing it formatted like this:
SELECT au_lname FROM authors (NOLOCK)
I am by no mean an expert, I follow what I read in books or from examples from others. And I have never read in a book go crazy with NOLOCK because it’s the bomb!
Any thoughts? I am trying to learn as much as I can before I raise my hand and say this might be a bad idea.
Thanks
NOLOCk
Jan 29, 1999Other than "dirty" reads, what are the cons of using NOLOCK throughout a query?
View 1 Replies View RelatedDTS- WITH (NOLOCK)
Mar 7, 2001Hi,
I have a job that runs 3 seperate DTS packages.
The first step imports a file and runs successfully.
The second step which is the 2nd DTS package is hanging in the execute mode until I manually stop the job. Apparently,We discovered a bulk insert that is blocking a select statement--both proccesses are within this second DTS package. I tried using the WITH (UNLOCK) on the tables but this DTS package is still failing.
Does anyone have any suggestion? It would be greatly appreciated.
Db2, Nolock
Mar 4, 2004Hi guys,
I am a new user for DB2.
In DB2 V8, i have a table with some no of columns.
table test
col1
col2
col3
col4
Now i want to issue a query like this.
select col1 from test with(NOLOCK) where col1 = <some value>
when i am executing this query on that time i am getting a error message like this...
SQL0158N The number of columns specified for "MT.TEST" is not the
same as the number of columns in the result table. SQLSTATE=42811
Anyone can help me???
i tried to find out.
I did the same thing with SQL server 2000.
I am not facing any problem there.
Thanks & Regards,
Muthu
NOLOCK Help
Jun 6, 2006Paul Randal,
There has been a discussion/debate going on this thread about the benefits and drawbacks of using the NOLOCK hint:
http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=67294
It occurred to me that you might know more about this than any of us, or at least be able to point us to a white paper or knowledge base article that explains the subject in more detail. Any light you can shed on the subject would be a big help.
CODO ERGO SUM
With (nolock)
Jan 8, 2008
is really helpful use "with (nolock)" sentence in selects??
100% useful?? disadvantages?
best regards
Joseph
NOLOCK On Views
Jun 2, 1999Hello,
Does anyone know if you place NOLOCK after a view in a select statement, if the effects trickle down to the tables in the view? Or does one have to add NOLOCK to each table within the view?
Thanks
NOLOCK Sentence
Jun 23, 2004Hello !!
I'm using the sentence NOLOCK for selects, but I have many sentences, Is there any way to set a parameter in the DBMS, to use NOLOCK parameter by default ???? I mean, I don't like to lock any table for selects.
Is It possible ???? How to do It (step by step) ?
Thanks !!
NOLOCK On Views
Nov 1, 2005Hey guys,
I came across a SQL statement, thought up by a developer, in which two views were joined with the NOLOCK hint:
SELECT v1.xxx, v2.yyy
FROM dbo.vw_SomeView v1 WITH (NOLOCK)
INNER JOIN dbo.vw_SomeOtherView WITH (NOLOCK) ON v1.id = v2.id
The views are not created the NOLOCK hint. So my question is: has the NOLOCK hint any effect here?
I've looked in the BOL and searched on the net but can't find anything on this particular topic.
Lex
PS. Personally I don't like to use views in JOINs. I've seen too many cases in which tables are joined twice just because they are part of both views. Further more I don't like the "random" use of NOLOCK because most people don't seem to understand the implications of it. But this is besides the point of my question ;)
Still Getting Blocked Despite WITH (NOLOCK)
Apr 5, 2006I'm running a heavy SELECT query using WITH (NOLOCK). This still causes other processes trying to INSERT in one of the tables to get blocked.
I thought the locking hint would prevent from blocking other processes?
NOLOCK And No Resources?
Mar 31, 2008What will happen if I'm running a query with the NOLOCK hint but the SQL Server has run out of resources?
Thanks!
NOLOCK Option ?
May 12, 2008Hi,
I was sreading about NOLOCK that it could prevent deadlocks but could return data which is not committed yet.
1) Should we use NOLOCK with select statements
2) If the transaction isolation level is set appropriately (e.g. Serializable)in the component (for e.g COM+ component) but NOLOCK is specified in the select then would it return uncommitted data. I mean if the transaction is controlled at hihger level then what will be the Pros and Cons of using NOLOCK.
Thanks
What Is The Purpose Of Using WITH NOLOCK
Aug 12, 2013What is the purpose of using WITH(NOLOCK)?
View 3 Replies View RelatedNolock Problem
Dec 28, 2007Hi!
select * from rubberstock_tbl_shoppingcarttemp
It dosent take datas from the table but
select * from rubberstock_tbl_shoppingcarttemp (nolock)
This querey takes the data from the table
what can i do to retrieve records through first query.I dont know what
is happening please explain and also dont know about nolock
Thanks in advance!
NOLOCK Clarifications
Feb 25, 2008When the NOLOCK hint is included in a SELECT statement, no locks are taken when data is read. This gives a Dirty Read in a result set.
The data retrieved in the select statement may not be correct since some other process might have updated the data while it was taken in the select statement.
Now, Can I know what is the use of NOLOCK? In which way we can make efficient use of NOLOCK ???
Select (nolock)
Mar 11, 2008Hi, I get an error when select * from a table with nolock....please help.
Cannot specify an index or locking hint for a remote data source
Question About NOLOCK
Mar 30, 2008Hi,
I have never used NOLOCK, or ROWLOCK, or anything of that sort. It's something I thought was over my head when I first encountered it and as I am gaining a better grip on SQL I have decided I want to try and tackle it. Also, because I think its causing me some problems :)
I recently implemented a new query into my application.
The query below gets the COUNT(*) of certain tables. Some of these tables are tall (5 million plus rows)
The counts returned are not absolutely critical information, and we are not joining or doing any other transactions based on this data. I believe running these counts on these pretty active tables (selects,inserts) are possibly causing slowdowns ?
Would using NOLOCK be an appropriate situation for something like this ? I am looking for a performance increase hopefully, and hoping there isnt much of a downside? I'm also not sure what type of reliability to expect from NOLOCK.
Any help much appreciated !!
Thanks once again
mike123
create PROCEDURE [dbo].[select_UserStats_Admin_TEST]
(
@userID int
)
AS SET NOCOUNT ON
DECLARE @Mail_Sent INT, @Mail_Received INT, @Comments_Sent INT, @Comments_Received INT,
@friendsListCount INT
SELECT @Mail_Sent = count(*) FROM tblMessage WHERE messageFrom = @userID
SELECT @Mail_Received = count(*) FROM tblMessage WHERE messageTo = @userID
SELECT @Comments_Sent = count(*) FROM tblComment WHERE CommentFromID = @userID
SELECT @Comments_Received = count(*) FROM tblComment WHERE CommentTo = @userID
SELECT @friendsListCount = count(*) FROM tblFriends WHERE userID = @userID
SELECT @Mail_Sent as Mail_Sent, @Mail_Received as Mail_Received, @Comments_Sent as Comments_Sent,
@Comments_Received as Comments_Received, @friendsListCount as friendsListCount
With Nolock Problem
Feb 17, 2006Hi,Is there a way to catch every select comming to sql and change it toselect with nolock?or how to make database READ UNCOMMITTED permanent?any ideas?Richard
View 3 Replies View RelatedDeadlocks And Use Of Nolock
Jul 20, 2005I am getting lot of deadlocks in my application. As it is very complexti avoid deadlocks at this stage of application we have done few stepsto lessen the impact.We have added retries after deadlock is capturted.We have added select * from TABLE with (nolock) wherever possible.But interestingly second step is not working. I have few simple selectstatements where i am using nolock criteria still I am gettingdeadlock victim error. Any idead why it happening. I thought as soonas I put nolock in the query it will ignore all the locks.My sp isCREATE procedure sp_Check_denomination@supply_till_idint,@product_codechar(4),@iso_currency_codechar(3),@denominationmoneyasdeclare @product_id numeric(5)select @product_id = product_id from product with (nolock) whereproduct_code = @product_codeif exists (select *from transaction_inventory TI with (nolock),product_ccy_denom PCD with (nolock)where TI.supply_till_id = @supply_till_idand TI.product_id = @product_idand TI.iso_currency_code= @iso_currency_codeand TI.denomination = @denominationand TI.product_id = PCD.product_idand TI.iso_currency_code = PCD.iso_currency_codeand TI.denomination = PCD.denominationand PCD.product_id=@product_idand PCD.denomination = @denominationand PCD.iso_currency_code=@iso_currency_codeand PCD.tradeable = 1)beginreturn(1)endelsebeginreturn(0)endGO
View 1 Replies View RelatedWhen To Use The NOLOCK Hint.
Jul 20, 2005Background:I am currently working on a mission critical web based applicationthat is accessed 24 hours a day by users from just about every timezone. We use MS SQL Server as our database and we have lots ofproblems with time-outs. We used to have lots of problems with locksuntil my management decided that we would use the WITH (NOLOCK) hinton EVERY select statement and WITH (ROWLOCK) on EVERY updatestatement. I have argued since the beginning that the NOLOCK hintshould be the exception and not the rule. Meanwhile we continue tohave problems related to time-outs.Problem:I'm the one that they call when there are time-out errors.I am a programmer first and a DBA when I have to be. I'd really liketo hear from some of you who are the opposite. I realize that thereare many factors that contribute to slow response from a databaseserver (indexes, RAM, disk speed, etc.), but what I really need tohear from an expert is whether or not using NOLOCK on **EVERY** queryin a 30GB database that has 344 tables is a bad idea.Thanks in advance,Stephen McMahonJoin Bytes!
View 2 Replies View RelatedNOLOCK Deprecated?
Dec 5, 2007Is the NOLOCK optimizer hint being deprecated? Or does this apply only to use of NOLOCK in UPDATE and DELETE statements or what exactly?
I can see that in this article that there are circumstances in which the hint is deprecated; however, I have developers that are acting like NOLOCK is about to be dropped entirely. As far as I know, that is not the case but I would definitely like some feedback on this.
NoLock Vs ReadPast
Oct 25, 2006I have been experiencing deadlock errors with two stored procs that I am using.
SP1 is a read query that gets all unprocessed orders (status = 0)
SP2 is an insert query that inserts new orders (Status = 0) uses a transaction.
I have a multithreaded application and once in a while the read query (SP1) will try to read a new row that has just been inserted but not committed yet hence the deadlock arises.
If i use a hint "With(NoLocks)" this will be a dirty read and still read the uncommitted insert from SP2 - is this correct?
Where as if I use hint "With(ReadPast)" this will now only read committed rows and hence the deadlock should not arise - it will not read any uncommitted rows - Correct?
So I think that it is better to use READPAST than NOLOCK. Any orders that have status = 0 not picked up will get picked up on the next round when SP1 is executed again.
Any thougths or suggestions are always appreciated.
Jawahar
SSIS - FTP Task
May 9, 2008Sorry guys, I'm really new to this. Can somebody tell me the easiest way to use the FTP task with a dynamic local path. I just want the FTP task to send whatever file is in the directory I specify.
I'm creating a package that extracts data from a table to a pipe-delimited file. I then use an external process (since using Expressions for it was a nightmare) to rename the file so that it'll reflect the previous month (e.g. April2008_report.txt). Then, I have to FTP that file. That's where my problem is. It seems I need to specify the exact filename on the local path of the FTP task, and since the filename will change each month... well, you see my problem.
Is there a way to tell the FTP task to just send *.txt, or something to that effect?
Thanks in advance for you help!
Thanks,
Mark
SSIS Task
Jun 21, 2006Hi ,
I have a master database. Based on certain criteria's I will be creating one new database. Once I have finished the creation, I have to check the value of a particular column in both database tables.
This is actually a status check. if both are not equal i have to update detail database table column value with master column value.
I thought i can use lookup transform for this. The problem is master database table's status datatype and detail table's status datatype is diff.
Can anyone suggest me any other way for this problem?
thanks in advance.
SSIS Task
Mar 26, 2008In my package i am loading data from a flat file into multiple tables like table1, table2, table3 all tables have a column called cust_num.
But data for this column cust_num is only coming in table1 and i need to load the data from this column to other tables how can i do this.
Need Help!!!! (SP Or SSIS Task)
Sep 6, 2007I have written the Dynamic TSQL S-Proc. Below is what i wanted to implement in SSIS using foreach loop container as a cursor. But i am little doubtful whether I can achieve the dynamics to this level. I know everything is possible but is it advisable to go for this simple Sproc or SSIS tasks.
I have some 15 tables being populated using this SPROC.
Here is some helpful description
ENTITYNAME gives me the table i need to work
FIELDNAME gives me the field i have to work on
CHANGEDVALUE gives me the value changed in that field
( This three i get from source table which is about 9000 rows and containing 15 possible ENTITY to be work on and 100's of their respective FIELD )
while in Cursors i need to get using these above variables other variables like
FLAG
KeyName
Thrugh SQL1 I get the KeyValue
then using this KeyValue check if the data exist update else insert new data.
QUESTION: IS THIS ADVISABLE to go for SSIS task or just carry with SPROC?
/*******************************************************************************************************/
DECLARE Table_Cursor CURSOR
FOR SELECT ENTITYNAME,FIELDNAME, KEYID, CHANGEDVALUE, UPDATEUSER, UPDATEDATE
FROM dbo.ChangedDimensionStage
OPEN Table_cursor
FETCH NEXT FROM Table_cursor INTO @ENTITY, @FIELD, @KEYID, @VALUE, @USER, @DATE
WHILE @@FETCH_STATUS = 0
BEGIN
DECLARE @FLAG NVARCHAR(50);
SET @FLAG = (SELECT LEFT(@ENTITY, (SELECT CHARINDEX( 'DIM', @ENTITY) -1)) )+ 'LastUpdateFlag';
DECLARE @KeyName NVARCHAR(50);
SET @KeyName = (SELECT LEFT(@ENTITY, (SELECT CHARINDEX( 'DIM', @ENTITY) -1)) )+ 'Key'
DECLARE @KeyValue NVARCHAR(50)
DECLARE @SQL1 NVARCHAR (1000)
SET @SQL1 = N'Select @KeyValueOUT = '+ @KeyName + ' FROM DW_Integration.dbo.MangFact WHERE ClaKey = ' + @KEYID + ' GROUP BY ' + @KeyName + ' HAVING SUM(TotalClaCount) > 0 OR SUM(IncidentOnlyClaCount) > 0 '
EXECUTE sp_executesql @SQL1, N'@KeyValueOUT INT OUTPUT', @KeyValue OUTPUT;
DECLARE @WC_TABLE NVARCHAR(100)
SET @WC_TABLE = 'WorkingCopy' + @ENTITY
DECLARE @SQL2 nvarchar (1000);
SET @SQL2 = 'IF EXISTS (SELECT '+ @KeyName +' FROM ' + @WC_TABLE + ' WHERE ' + @KeyName + ' = ' + @KeyValue + ' )' +
' BEGIN UPDATE ' + @WC_TABLE + ' SET '+ @FIELD + ' = '''+ @VALUE + ''' WHERE ' + @KeyName + ' = ' + @KeyValue +'; END' +
' ELSE BEGIN
INSERT INTO '+ @WC_TABLE + ' SELECT * FROM DW_Integration.dbo.' + @ENTITY + ' WHERE ' + @Flag + ' = ' + '''Y''' + ' AND '+ @KeyName + ' = ' + @KeyValue + ';' +
'UPDATE ' + @WC_TABLE + ' SET '+ @FIELD + ' = '''+ @VALUE + ''' WHERE ' + @KeyName + ' = ' + @KeyValue +'; END'
EXECUTE sp_executesql @SQL2
FETCH NEXT FROM Table_cursor INTO @ENTITY, @FIELD, @KEYID, @VALUE, @USER, @DATE
END
CLOSE Table_cursor
DEALLOCATE Table_cursor