Locks per Object

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The Locks per Object screen shows the same information as the Locks per Process window, but arranged differently.

 

The Locks per Object screen on server Iduna

 

The window consists of two parts - the object list and the lock list. The object list shows a list of all locked objects on a given server. If you select one of the objects, the right part of the window will list the process IDs that have a lock on the object, and what type of lock and locking mode is used.

 

In the example screenshot above, you can see that user "sa" on database "Northwind" is clearly doing something with table "Categories" as that table has several locks placed upon it.

 

You can kill a process - and therefore release the lock(s) - by using the context menu in the Processes/locks part or the button on the toolbar.

 

There are several locking modes:

Shared (S)

 

Used for operations that do not change or update data (read-only operations), such as a SELECT statement.

 

Update (U)

 

Used on resources that can be updated. Prevents a common form of deadlock that occurs when multiple sessions are reading, locking, and potentially updating resources later.

 

Exclusive (X)

 

Used for data-modification operations, such as INSERT, UPDATE, or DELETE. Ensures that multiple updates cannot be made to the same resource at the same time.

 

Intent

 

Used to establish a lock hierarchy. The types of intent locks are: intent shared (IS), intent exclusive (IX), and shared with intent exclusive (SIX).

 

Schema

 

Used when an operation dependent on the schema of a table is executing. The types of schema locks are: schema modification (Sch-M) and schema stability (Sch-S).

 

Bulk Update (BU)

 

Used when bulk-copying data into a table and the TABLOCK hint is specified.

 

 

And several lock types:

RID

 

Row identifier used to lock a single row within a table.

 

KEY

 

Row lock within an index. Used to protect key ranges in serializable transactions.

 

PAG

 

Data or index page.

 

EXT

 

Contiguous group of eight data pages or index pages.

 

TAB

 

Entire table, including all data and indexes.

 

DB

 

Database.

 

 

For more information on locking, see the Microsoft SQL Server documentation.