Table 34-1 shows the types of scans performed during update statistics, the types of locks acquired, and when sorts are needed.
update statistics specifying |
Scans and sorts performed |
Locking |
|
|---|---|---|---|
Table name |
|||
Allpages-locked table |
Table scan, plus a leaf-level scan of each nonclustered index |
Level 1; shared intent table lock, shared lock on current page |
|
Data-only-locked table |
Table scan, plus a leaf-level scan of each nonclustered index and the clustered index, if one exists |
Level 0; dirty reads |
|
Table name and clustered index name |
|||
Allpages-locked table |
Table scan |
Level 1; shared intent table lock, shared lock on current page |
|
Data-only-locked table |
Leaf level index scan |
Level 0; dirty reads |
|
Table name and nonclustered index name |
|||
Allpages-locked table |
Leaf level index scan |
Level 1; shared intent table lock, shared lock on current page |
|
Data-only-locked table |
Leaf level index scan |
Level 0; dirty reads |
|
Table name and column name |
|||
Allpages-locked table |
Table scan; creates a worktable and sorts the worktable |
Level 1; shared intent table lock, shared lock on current page |
|
Data-only-locked table |
Table scan; creates a worktable and sorts the worktable |
Level 0; dirty reads |
|
