What is Tablockx?
TABLOCKX means an exclusive lock (You can’t access the table until it finishes the execution) TABLOCK is used for operations that do not change the data.
What is Sp_getapplock?
The lock resource created by sp_getapplock is created in the current database for the session. Each lock resource is identified by the combined values of: The database ID of the database containing the lock resource. The database principle specified in the @DbPrincipal parameter.
What is tab lock in SQL Server?
TABLOCK. Forces SQL Server to use a table-level lock instead of row- or page-level locks. If used with HOLDLOCK, then the lock will be held until the transaction completes. Otherwise, the lock is released as soon as the data is read. For SELECT statements, this hint forces shared table locks.
What is SQL Server Readpast?
READPAST specifies that locked rows be skipped during the read. READPAST only applies to transactions operating at the default READ COMMITTED isolation level, and will only read past row-level locks. READPAST can only be used in SELECT statements.
Why is select into faster than insert into?
The first article compares insert..select with select into for temporary tables, and the second compares these two in general. In general insert..select is slower because it’s a fully logged operation. select into is minimally logged in the simple and bulk logged recovery models.
Can we use with Nolock in insert statement?
SELECT statements only with NOLOCK The NOLOCK and READUNCOMMITTED lock hints are not allowed for target tables of INSERT, UPDATE, DELETE or MERGE statements.
What is Xp_userlock?
SP_getapplock is a wrapper for the extended procedure XP_USERLOCK . It allows you to use SQL SERVERs locking mechanism to manage concurrency outside the scope of tables and rows. It can be used you to marshal PROC calls in the same way the above solutions with some additional features.
What is Maxdop setting in SQL Server?
The maximum degree of parallelism (MAXDOP) is a server configuration option for running SQL Server on multiple CPUs. It controls the number of processors used to run a single statement in parallel plan execution. The default value is 0, which enables SQL Server to use all available processors.
What is option Maxdop 1 in SQL Server?
Sets the maximum number of processors the query processor can use to execute a single index statement. Fewer processors may be used depending on the current system workload.
What’s the difference between tablock and tablockx exclusive locks?
Big difference, TABLOCK will try to grab “shared” locks, and TABLOCKX exclusive locks. If you are in a transaction and you grab an exclusive lock on a table, EG: No other processes will be able to grab any locks on the table, meaning all queries attempting to talk to the table will be blocked until the transaction commits.
Which is better nolock or tablockx in SQL?
Nolock means you can read some locked rows (with shared locks). But you still have to wait on other locks. Tablockx means you block whole table with exclusive lock for other queries – other session cannot make locks, you cannot be blocked after you block whole table. Tablockx is mostly used for rapid inserts.
When does tablock grab a lock on a table?
No other processes will be able to grab any locks on the table, meaning all queries attempting to talk to the table will be blocked until the transaction commits. TABLOCK only grabs a shared lock, shared locks are released after a statement is executed if your transaction isolation is READ COMMITTED (default).
When to use shared or shared tablock in SQL?
If your isolation level is higher, for example: SERIALIZABLE, shared locks are held until the end of a transaction. Shared locks are, hmmm, shared. Meaning 2 transactions can both read data from the table at the same time if they both hold a S or IS lock on the table (via TABLOCK ).