1. Positioning Oracle is divided into two parts, one is development and the other is management. Development mainly involves writing stored procedures, triggers, etc., and using Oracle's Develop tool to create forms. A bit similar to programmers, they need to have strong logical thinking and creative abilities. Personally, I think it will be more difficult, and they are young. Management requires a deep understanding of the principles of Oracle database, the ability to control the overall situation and close thinking. , the responsibility is greater, because a small mistake will bring down the entire database. Compared with the former, the latter values experience more.
Because of the heavy responsibility of database management, few companies are willing to hire someone who is new to Oracle to manage the database. For young people who have just graduated, you can choose to do development first, and then transition to database management after gaining certain experience. Of course, this still depends on the individual’s actual situation.
2. Learning methods My method is very simple, that is: read, think, write notes, do experiments, think again, write notes again. After reading the theoretical things, calm down and think about it, ask yourself a few more whys, and then put Make notes on the knowledge points you have learned and thought about; when you can't figure it out or have questions, do an experiment and think about how this happened. Similarly, write down the results of the experiment. Thinking and doing experiments are to understand this knowledge point in depth. The process of taking notes is also a process of clarifying one's own thoughts.
The process of learning is the process of making a problem from fuzzy to clear, and then from clear to fuzzy. And every change means you have learned a new knowledge point.
The process of learning is also a process from point to line, from line to network, and from network to surface. When the dots turn into lines, you will always feel enlightened. When you meet someone online, you are a master. Many netizens, especially beginners, will ask questions on the forum whenever they encounter a problem. Before asking, have you checked the books, have you done your own research, and have you Search the forum? This is called mental inertia. Without a diligent learning attitude, no matter what you learn, you will not succeed.
3. Oracle's system Oracle's system is very large. To learn it, you must first understand the Oracle framework. Here, I will briefly talk about the architecture of Oracle so that beginners can have an overall understanding of Oracle.
1. Physical structure (composed of control files, data files, redo log files, parameter files, archive files, and password files)
Control file: contains the necessary information to maintain and verify the integrity of the database. For example, the control file is used to identify data files and redo log files. A database requires at least one control file. Data file: a file that stores data. Redo log file: contains the Changes made to the database are logged, enabling data recovery in the event of a failure. A database requires at least two redo log file parameter files: defines the characteristics of Oracle routines, for example, it contains parameters to adjust the size of some memory structures in the SGA. Archive file: is an offline copy of the redo log file, these copies may be used from Recovery from media failure is necessary.
Password file: authenticate which users have the authority to start and shut down Oracle routines 2. Logical structure (table space, segment, area, block)
Table space: It is the basic logical structure in the database, a collection of a series of data files.
Segment: It is the space area occupied by the object in the database: It is a large storage space block reserved for data at one time: the most basic storage unit of ORACLE, specified when establishing the database 3. Memory allocation (SGA and PGA)
SGA: It is a memory area used to store database information. This information is shared by the database process. It contains the data and control information of the Oracle server. It is allocated in the actual memory of the computer where the Oracle server resides. If the actual memory is not enough, it is written to the virtual memory.
PGA: Contains data and control information for a single server process or a single background process. Contrary to SGA shared by several processes, PGA is an area used by only one process. PGA is allocated when the process is created and recycled when the process is terminated. 4. Background process (Data writing process, log writing process, system monitoring, process monitoring, checkpoint process, archiving process, service process, user process)
Data writing process: Responsible for writing changed data from the database buffer cache to the data file Log writing process: Writing changes in the redo log buffer to the online redo log file System monitoring: Checking the consistency of the database if necessary It also starts the recovery process of the database when the database is opened. Monitoring: Responsible for cleaning up resources when an Oracle process fails. Checkpoint process: Responsible for updating the control file and data whenever changes in the buffer cache are permanently recorded in the database. Database status information in the file.
Archiving process: Back up or archive the full log group every time the log is switched. Service process: User process service.
User process: On the client side, it is responsible for passing the user's SQL statement to the service process and getting back the query data from the server segment.
5. Oracle routines: Oracle routines consist of the SGA memory structure and the background process used to manage the database. A routine can only open and use one database at a time.
6. SCN (System Change Number): System change number, a serial number maintained internally by the system. It is automatically increased when the system needs to be updated. It is an important symbol in the system to maintain data consistency and sequential recovery.
4. In-depth study of management: You can take the OCP certificate, first have a systematic study of Oracle, and then read Oracle Concepts and Oracle online document. You will have a deeper understanding of the principles of Oracle. At the same time, you can start to conduct research on some special topics such as: RMAN, RAS, STATSPACT, DATAGUARD, TUNING, BACKUP&RECOVER, etc.
Development: For those who want to develop Oracle, after understanding the basic architecture of Oracle, you can focus on PL/SQL and Oracle's development tools. PL/SQL mainly includes how to write SQL statements, how to use Oracle's own functions, how to write stored procedures, stored functions, triggers, etc. Oracle's development tools are mainly Oracle's own Developer Suite (Oracle Forms Developer and Reports Developer). Learn how to use these tools proficiently.
This article comes from the CSDN blog. Please indicate the source when reprinting: http://blog.csdn.net/daihu1986/archive/2008/09/26/2982400.aspx
This article comes from the CSDN blog. Please indicate the source when reprinting: http://blog.csdn.net/chenliubin/archive/2009/12/21/5049960.aspx
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