1, the use of the lock
- In order to avoid the same time compete for resources database, the database is locked, only the user can use to get the key;
2, the lock granularity
- Line Lock (Row) ---> Page Lock (Page) ---> District lock (Partition 8 pages) ----> lock table (Table)
3, the lock type
- Shared lock: read-only data for all operations (SELECT);
- Modify locks: lock the resource may be used to modify (Update) in the modify operation initialization phase;
- Exclusive lock :( exclusive lock) to modify the data reserved; (exclusive lock can not be compatible with other locks)
- Schema locks: locks into structure modification (Sch-M) and a structural stability lock (Sch-S);
- Intention locks: Description eligible SQL Server shared lock or an exclusive lock intention underlying resource; (contains three types: intent exclusive locks (IX), and IS intent share lock intent exclusive shared lock)
- Bulk copy lock: Lock using bulk data modification bulk copy;
4, view the database locks
- DMV system function: sys.dm_tran_locks