OS Conceptual Framework OS Conceptual Framework Figure 1: OS Conceptual Framework physical addresses shared processes and address translation CPU must be shared threads processes aren’t tr

Scheduling Concept Why we need scheduling? For multitasks and concurrency. Scheduling is only useful when there is not enough resources. preemption is the basic assumption for fine-grained schedulin

Demand Paging Modern programs require a lot of physical memory, but they don’t use all their memory all of the time. 90-10 rule: programs spend 90% of their time in 10% of their code. Use main memor

Transaction Management A single user’s access to the database (DB) is represented as one or more transactions executed by the Database System (DBS), including operations such as select, insert, dele

Based on 12 rules to optimize relational algebra expression

In this chapter, we focus on conceptual design.

*Features of Good Relational Design flowchart TD A[Application problems in real words] -->|Requirements analysis| B[Specification of user requirements] B -->|Conceptual DB design| C[DB

Accessing SQL from a Programming Language API (application program interface) to interact with DB server Application conducts data processing, and makes calls to Connect with the database server Se

Join Expressions Def. Join operations take two relations and return as a result another relation. Def. Join operations is a Cartesian product requires that tuples in two relations match. Def. Join co

Threats to FS Reliability Operation interruption A crash or power failure A file operation often consists of many I/O updates to the storage An example: mv ./dir1/file1 ./dir2/file2 Writing the dir