Definition
The lock table is a table in the main memory of the enqueue server that records the current locks in the system. For each elementary lock, the table specifies the owner, lock mode, name, and the fields in the
locked table.Use
The lock table is used to manage locks. Every time the enqueue server receives a lock request, the system checks the lock table to determine whether the request collides with an existing lock (see
Lock Collisions). If this is the case, the request is rejected. Otherwise, the new lock is written to the lock table.Structure
Each elementary lock corresponds to a data record in the lock table.
The structure of the lock entries is shown below.
The individual field have the following meaning:
Field |
Contents and meaning | |
Owner_1 |
Owner id and cumulation counter of owner_1: the ID contains the computer name, the work process, and a timestamp. It is also used to identify the SAP LUW. The cumulation counter specifies how often the owner has already set this elementary lock. | |
Owner_2 |
The above applies here to owner_2 | |
Backup Id |
Backup Id (index indicating where the lock entry is stored in the backup file) and backup flag (0 (no backup) or 1 (backup)). | |
Elementary lock |
Lock mode |
S (Shared lock, read lock)E (Exclusive lock, write lock) X (eXclusive lock, extended write lock, cannot be cumulated) |
Name |
Name of the database table in which fields are to be locked | |
Argument |
Locked fields in the database table (linked key fields, can also contain wildcards) |
Integration
The lock entries can be viewed for diagnosis purposes. This is described in the section entitled
Managing Lock Entries.