Insomnia can be caused by psychiatric conditions such as depression. Psychological struggles can make it hard to sleep, insomnia itself can bring on changes in mood, and shifts in hormones and physiology can lead to both psychiatric issues and insomnia at the same time.
Lock modes specify different kinds of locks. The choice of which lock mode to apply depends on the resource that needs to be locked. The following three lock types are used for row-and page-level locking: 1  Shared (S). 2  Exclusive (X).3  Update (U).nce an exclusive lock is set for the page (or row), no other lock can be placed on the same resource. NOTE. The database system automatically chooses the appropriate lock mode according to the operation type (read or write). An update lock can be placed only if no other update or exclusive lock exists.
/var/lock. Many programs follow a convention to create a lock file in /var/lock to indicate that they are using a particular device or file. This directory holds those lock files (for some devices) and hopefully other programs will notice the lock file and won't attempt to use the device or file./var' contains variable data, i.e. files and directories the system must be able to write to during operation, whereas /usr should only contain static data. Some directories can be put onto separate partitions or systems, e.g. for easier backups, due to network topology or security concerns.