Asked by: Zaida Almeida
technology and computing databases

What is Lck_m_ix?

Last Updated: 8th April, 2020

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LCK_M_IX: this wait type occurs when a thread is waiting for a table or page IX lock so that a row insert or update can occur. It could also be caused by using a restrictive isolation level like REPEATABLE_READ or SERIALIZABLE that requires S and IS locks to be held until the end of a transaction.

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Accordingly, what is wait types in SQL Server?

In SQL Server, wait types represent the discrete steps in query processing, where a query waits for resources as the instance completes the request. Response time analysis assesses database performance by analyzing time spent at each wait type.

Additionally, what is Pageiolatch_sh? PAGEIOLATCH_SH. Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem. In practice, this almost always happens due to large scans over big tables.

In this manner, what is Lck_m_u?

LCK_M_U is a wait for an update lock. Something's trying to update and whatever it wants to update is locked already. Start by identifying what is causing the blocking and see if it can be optimised, then look at what is blocked and how it can be optimised.

Is read committed snapshot on?

No locks are placed on the data when it is read, so SNAPSHOT transactions do not block other transactions from writing data. If you set the READ_COMMITTED_SNAPSHOT database option to ON, the database engine uses row versioning and snapshot isolation as the default, instead of using locks to protect the data.

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