database system concepts

mapping and also inherits the address returned by Mmap (), so that the parent-child process can communicate through the mapped area. Note that this is not a general inheritance relationship. In general, child processes maintain separate variables inherited from the parent process. The address returned by the mmap () is maintained by the parent-child process together.The best way to implement shared memory for a genetically-related process should be to use anonymous memory mapping. At this point

logical partitions within the extended partition only after partitioning the extended partition, that is, the logical partition is within the extended partition.19. When I use Fdisk-l/dev/sdb to view disk partition status, I find that there are several partitions: SDB1, SDB3, SDB5, SDB6, sdb7, so please figure out how many primary partitions and several logical partitions there are in this disk?A: A primary partition, three logical partitions (SDB5,SDB6,SDB7)20. What is the method to see how mu

Tags: databaseService mysqld Start: Start the database serviceMySQL * mysql_init (MySQL *mysql); initializes the MySQL handle. If MySQL is null, one is assigned.To connect to a database:650) this.width=650; "src=" Http://s3.51cto.com/wyfs02/M01/82/8E/wKioL1daWLbDXXl_AAA1DUZ_Pmk532.png "style=" float: none; "title=" QQ picture 20160609103811.png "alt=" Wkiol1dawlbdxxl_aaa1duz_pmk532.png "/>Close connection:v

system Throughput (TPS), user concurrency, performance test concepts and formulasThe throughput of a system (load capacity) is closely related to the request for CPU consumption, external interfaces, IO, etc.The lower the CPU consumption of a single request, the more the external interface, the faster the ID response, the greater the throughput of the

Operating System Concepts Learning Note 9 Thread overviewA single process can include multiple control threads.Thread--a basic unit of CPU utilization, which is the basis of forming multi-threaded computer.A thread is the basic unit used by the CPU and consists of a thread ID, a program counter, a collection of registers, and a stack. It shares code snippets, data segments, and other operating

Tags: abstract family concept technology share strong processor picture mil INFAbstract concepts of the operating system Files: Abstraction of I/O devices Virtual Memory: Abstraction of main memory and disk I/O devices Process: Abstraction of processor, main memory, and I/O devices Virtual Memory: Provides an illusion for a process The memory that each process sees is con

, starting to execute the process, and so forth. 2, independent of each other, the memory is isolated using virtual memory, each process has a private address space, as if our program exclusive and use of memory.V. Process life cycle for a program, the process has three states: run, Hang, die. 1, set up a task (create a process) 2, ready to run (waiting for the CPU to allocate time slices) 3, is running (in the actual running state, if not allocated to the actual CPU chip, continue to wait) 4, s

Tags: high-end storage ibm xiv scale out Let's take a look at the most basic concepts in XIV: PartitionsThe fundamental building block of a logical volume is known asPartition. Partition is 1 MB (Kb), including a primary copy or secondary copy of data. Each partition corresponds to a region of a separate physical disk, the storage Administrator does not know which disk a partition corresponds to. It is controlled by the

Linux File System concepts and basic operations (format partitions to create a file system and view a specified file system) 9.1 File System Concept (Overview) The operating system (OS) is used to manage files and data through the

Tags: regular pre-binary span binary between varchar bin positive A. Basic database Concepts I. Database: A collection of table and database Access objects, where the table stores different entity information, and each row of data corresponds to an entity's descriptive information I. Entities and records: 1entities are

Tags: span system model Style property color considerations Dom Row recordFirst, the relationship model The relational model is one of the most important data models. The relational Database model system uses the relational model as the data organization way. Data structure of the relational model: 　　relationship : a table 　　tuple : A row of records. 　　Propertie

Step1. Sqlplus/' as Sysdba ' sql*plus:release 10.2.0.1.0-production on Sat Mar 3 22:48:27 Copyright (c) 1982,%, Oracl E. All rights reserved. Connected to a idle instance. Step2. Startup Nomount ORACLE instance started. --> Total System Global area 167772160 bytes Fixed Size 1218316 bytes Variable Size 104859892 bytes Datab ASE buffers 58720256 bytes Redo buffers 2973696 bytes oracle@db1:~> Ps-ef | grep ora_ Oracle 3626 1 0 22:48? 00:00:00 OR

Introduction to operating systems, operating system concepts A computer system can receive and store information according to human requirements. It can process and provide the required results. The results (output information) depend on the received information (input information) and corresponding processing methods. 1. Learning Process: I used to learn some re

References:LinuxKernel design and implementationHttp://www.ibm.com/developerworks/cn/linux/l-cn-vfs/Http://www.ibm.com/developerworks/cn/linux/l-linux-filesystem/Http://www.ibm.com/developerworks/cn/linux/l-cn-read/index.html 1. Important Concepts "Everything is a file" is one of the basic philosophies of Unix/Linux. Not only common files, directories, character devices, Block devices, sockets, etc. are treated as files in Unix/Linux. Although they

Information in a logical model can be described in three concepts: (1) entity (if an object has many features and values, it may be an entity) (2) attribute (if an object has a property value, it may be an attribute) (3) relationship (if an object description contains a verb phrase, it may be a link) The database design can be divided into the following four parts: (1) Normalization and improve

believe that every developer who calls sensitive APIs wants their applications to become a trusted MIDlet, so that the applications can run smoothly. However, how to verify a MIDlet suite as a trusted suite and assign it all the protection domains on the implementation of the device. Generally, devices use digital signature technology to achieve this.Obtaining a digital signature is a process of test and authentication. Testing requires a professional company and certification requires a truste

Android system development (8)-basic concepts of linx Processes1. in the traditional sense, the proc file system is used to store information on Block devices. The/proc directory is a virtual file system, where the data is stored in the memory, therefore, this directory does not occupy any hard disk space. It mainly in

Linux file system: records the overall information of this filesystem, including the total amount, usage, and remaining amount of inodeblock, as well as file system formats and related information such as inode: records file attributes, a file Linux file system Linux file system involves several basic

guarantees that the data will be intact and consistent regardless of the business system accessing the database. 3. The final consideration is self-writing business logic, but this is cumbersome, programming complex, inefficient. 6. What is a transaction? What is a lock? A : A transaction is a grouping of SQL statements that are bound together as a logical unit of work, and if any one statement fails th

with each other and synchronize behavior-especially with regard to the use of shared variables. In addition, the IPC and synchronization mechanisms enable threads to communicate with each other.? The main advantage of threading is that it is easier to share data between threads, and for some algorithms it is more natural to implement multi-threading than to implement multiple processes. Furthermore, it is obvious that multithreaded applications can benefit from parallel processing of multiproce