What is lock wait?
A lock wait occurs when a transaction tries to obtain a lock on a resource that is already held by another transaction. When the duration of the lock wait time is extended, this results in a slow down of SQL query execution.
What is wait in SQL Server?
The “waits” are what SQL Server tracks. … It’s the way SQL Server’s scheduling system works. A thread is using the CPU (called RUNNING) until it needs to wait for a resource. It then moves to an unordered list of threads that are SUSPENDED.
Is it safe to increase Innodb_lock_wait_timeout?
Changing the timeout to 1 is quite safe (once you understand GLOBAL vs SESSION). The only thing that will change is the frequency of getting that error.
What is Ft_iftshc_mutex?
(Republishing, or using this info in a commercial product/website, is prohibited without permission. Description: This wait is when a thread that is participating in a full-text operation is waiting for synchronization with other full-text worker threads.
What is Lck_m_u?
A LCK_M_U is an update lock on a table/index (not on a database), that’s quite normal when you update data in a database.
What is SQL wait stats?
What is SQL Server wait statistics? The wait times are captured and recorded by the SQL Server and all this captured information called wait statistics and it provides assistance to resolve problems that are related to the SQL Server performance.
What is table lock in SQL?
The LOCK TABLE statement allows you to explicitly acquire a shared or exclusive table lock on the specified table. The table lock lasts until the end of the current transaction. … Explicitly locking a table is useful to: Avoid the overhead of multiple row locks on a table (in other words, user-initiated lock escalation)
What is a SQL lock?
Locks are held on SQL Server resources, such as rows read or modified during a transaction, to prevent concurrent use of resources by different transactions. For example, if an exclusive (X) lock is held on a row within a table by a transaction, no other transaction can modify that row until the lock is released.
What is difference between locking and blocking?
Locking is the mechanism that SQL Server uses in order to protect data integrity during transactions. Block (or blocking lock) occurs when two processes need access to same piece of data concurrently so one process locks the data and the other one needs to wait for the other one to complete and release the lock.