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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.
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.
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.
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.