oracle数据库基本概念（Basic concepts of Oracle Databa）
Oracel itlf is a complete management system, so the structure of ORALCE is divided into two parts:
The management system and the backstage rver (databa).
(1) management system
A collection of Oracle executable tools, divided into two parts: process structure and memory structure
(2) process structure
The startup of an application in OS is divided into ur process and rver process according to who calls the application
A: ur process: application ur calls.
wrappers
Function: Send a ur request processing result databa.
B: rver process: Oracle rvice is started, the application will automatically start the call.
Effect: request processing receives the request of the ur, the processing result.
Know: 6 rver process
Write process: databa cache data to the data file.
The log cache write process: redo log writes the redo log files.
Process monitor: operation of automatic monitoring ur process
清艳英语官方网站Checkpoint process: dirty data processing process
The process of monitoring system: the realization of databa backup and restore process.
Archiving process: automatically archived redo log
(3) memory structure
Memory space occupied by an application. According to the application of the caller of different memory structure is divided into PGA and SGA.
A:PGA:
The program global area, the ur process memory space occupied and exclusive.
B:SGA
System wide area, rvice startup, shared memory space for rver process and ur process automatically.
Form：
Data buffer: buffer for processing data
Log buffer: Handling redo logs
Shared storage pool: compiled SQL statements and data
Java pool: store Java statements
Large pool: the storage capacity of data and realize the databa backup and restore.
(4) backstage databa
Realize the collection of data storage and data management and document management object. Into the physical and logical structure to realize the data storage and management
A: physical structurebec中级
The physical structure is really ud to store data files. The collection reflects the Oracle databa in the physical disk is a ries of documents. Divided into three core files and three auxiliary files.
新东方英语学校Three core files: data files, control files, redo log files.
Three auxiliary files: the parameter file, the password file and archive log files
msl
The collection of the documents form a databa.
B: logical structure
The way to implement data management.
Block: the basic unit of Oracle IO, the default is a multiple of 4k.
The data interval: Oracle basic unit space allocation. Default 16 block.
Data: data storage, a ries of continuous data interval. (data gment, gment, rollback gment, temporary gment)
Databa objects: realize logic object data management. Oracle has 21 clock databa objects.
Table view constraint, index quencer, synonym, process function, trigger, package, package exception
sheilaTable space: object logic to manage multiple data files
data ba
So. To u Oracle databa, you need to build your own tablespace, build your own data files, build your own urs, assign your own permissions, create your own databa objects, and store your own data.
Ur process
Process structure
Server process
management system
jimmy eat world
orbis
PGA
hubMemory structure
SGA
data ba
Core file
Physical structure
Auxiliary file
Background databa
data block
Logical structure data interval Data gment
Databa object
Tablespace
data ba
pwb
