RowLock
Jan 28, 2008Advantage and disadvantage of using rowlock in sql server 2005.
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Insert Should Aquire Only Exclusive Rowlock. Why Does Insert Block Select With ( Updlock, Rowlock )?
Mar 12, 2007Here is the situation i am stuck with, see the example first and below explained the problem:
-- 'SESSION A
create table foo (
id integer,
pid integer,
data varchar(10)
);
begin transaction
insert into foo values ( 1, 1, 'foo' )
insert into foo values ( 2, 1, 'bar' )
insert into foo values ( 3, 1, 'bozo' )
insert into foo values ( 4, 2, 'snafu' )
insert into foo values ( 5, 2, 'rimrom' )
insert into foo values ( 6, 2, 'blark' )
insert into foo values ( 7, 3, 'smeg' )
commit transaction
create index foo_id_idx on foo ( id )
create index foo_pid_idx on foo ( pid )
begin transaction
insert into foo values ( 9, 3, 'blamo' )
-- 'SESSION B
begin transaction
select id, data from foo with ( updlock, rowlock ) where id = 5;
-- Problem:
-- Uncommitted transaction in session A, with insert into table FOO, aquires lock on index foo_pid_idx which BLOCKS select with ( updlock, rowlock ) in session B.
-- Insert should aquire only exclusive rowlock. Why does insert block select with ( updlock, rowlock )?
Appreciate your help,
Rajesh.
RowLock
Jul 18, 2001Hello,
Is there any way to specify the sql server to use row level locking in transaction.
Thanks
Val
Rowlock With Inner Join
Oct 26, 2007Him
I am trying to issue the following statement to lock a record with inner join but I have an error:-
SELECT amaster.acctno,bmaster.balance,bmaster.YEAR
FROM amaster [ROWLOCK] with (Xlock)
INNER JOIN bmaster
ON amaster.acctno = bmaster.acctno
WHERE (bmaster.YEAR = 2007) acctno = 10000100
ORDER BY amaster.acctno
The error:
Msg 4104, Level 16, State 1, Line 1
The multi-part identifier "amaster.acctno" could not be bound.
Thanks
XLOCK And ROWLOCK
Jul 20, 2005Hello,I need to lock only one row with exclusive lock (nobody else can see ormodify this row), but when I use "with (xlock, rowlock)" it doesn't work.XLOCK always locks whole table.Can anybody help me?Thanks in advance.Magda
View 1 Replies View RelatedRowlock V. Optimistic Concurrency
Feb 8, 2008Hi,Sql-Server 2000, 2005.A report fetches a lot of rows using the "WITH (ROWLOCK)" syntax (thesql is generated on the fly by a tool and not easily changeable).SELECT col1, col2 FROM mytab WITH (ROWLOCK) WHERE ...."The select-clause runs for several minutes.Another user fetches one of those rows and tries to update it. Theresult is a lock timeout.I suppose that the long running select-clause has put a shared lock onthe rows and the updater (exclusive-lock) will have to wait for thelong-running select and so the lock timeout is expiring.Are all those rows "shared locked" until all are fetched?Would there be any change if the "WITH (ROWLOCK)" is removed, isn'talthough "shared lock" the default behaviour?The "WITH (NOLOCK)" would probably help?What about the definition of optimistic concurrency, shouldn't allselect-clauses contain "WITH (NOLOCK)" to allow an optimisticconcurrency scenario?Regards Roger.PS. Probably some misunderstanding from me here, but this should bethe right place to get it right.
View 8 Replies View RelatedIsolation Level VS With(nolock|rowlock)
May 22, 2008Hello all.
I'm a litle confused about what's best to use, either isolation levels or locking per table.
Cause there are some queries in the stored procedures where I don't need locking i.e. when I check the status of client, but other queries where I do need locking like when I check the existence of a product.
What's best to use, can I combine both? Could you explain it thecnically?
lots of thanks in advance
SQL Seems To Ignore UPDLOCK && ROWLOCK Hints
Dec 3, 2007
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.
-Mike
NOLOCK/ROWLOCK (good Or Bad Guys?)
Nov 9, 2007Reading about avoiding deadlocks in SQL, I have found different opnions about whether using or not NOLOCK/ROWLOCK hints on SELECT/UPDATE/DELETE statements. I have several applications executing transactions on the same databases and tables, including inserts, updates and deletes. I wonder if by using NOLOCK/ROWLOCK I could decrease the chances of having deadlocks. At least using ROWLOCK on my update statements?. I just need some advice here.
Regards.
SQL Server 2008 :: Update With Xlock / Rowlock And Read With Nolock
Feb 10, 2015I have a stored procedure that updates a table. I also have an UDF that allows dirty reads (nolock).
What's the precedence level in SQL server? If I add xlock,rowlock to the update statement, will the dirty read wait for the update transaction to commit, or will it perform a dirty read regardless of the locking scheme in the update statement?
SSIS Transaction Management && Strange Deadlock When Using XLOCK, ROWLOCK
Jun 7, 2007I have a SSIS package that is run from one job, nowhere else. The package has TransactionOption NotSupported.
In the SSIS package I first have a sequence container that has TransactionOption Required (Serializable). The sequence container contains several Execute SQL tasks that access the same SQL Server 2005 database. The Execute SQL tasks have TransactionOption supported / Serializable. The first SQL statement is:
select p.column_name
from table_name p with (XLOCK, ROWLOCK)
where p.second_column_name = 'COLUMN_VALUE'
After this there are a couple of SQL tasks, and finally a task containing the following SQL:
select p.third_column_name
from table_name p
where p.second_colomn_name = 'COLUNM_NAME'
The idea is that the first query exclusively locks the row in the table_name-table for mutual exclusion purposes, i.e. so that if for some reason the SSIS package would be executed simultaneously two or more times, only one package execution could lock the row and proceed and the other executions will have to wait. There's an index on column second_column_name in the table to avoid the select locking other rows in addition to the required row.
Some questions:
1) Is it so in my setup that when SSIS runtime executes the sequence container it creates a transaction in the beginning of the sequence container and commits the transaction in the end of the sequence container? And in my setup the Execute SQL tasks in the sequence containar are executed under the same transaction?
2) I have a problem that the second query sometimes gives this error:"ErrorCode: -1073548784. ErrorDescription: Executing the query "XXXXX" failed with the following error: "Transaction (Process ID 73) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly."
The 1st query has locked the row for the transaction. How can the second query be deadlocked, shouldn't the transaction have a lock on the row? I'd understand if the 1st query failed sometimes, but don't understand how the 2nd quey can fail.
r,
JM