Basic knowledge of oracle architecture (entry level)

Basic knowledge of oracle architecture (entry level)_PHP tutorial

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Release： 2016-07-13 17:02:27

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Author: Lu Yang
To learn Oracle, it is best to first understand the Oracle framework. In this way, we have an overall understanding of Oracle and have a strategic position
1. Physical structure (composed of control files, data files, redo log files, parameter files, archive files, and password files)

One The data in the database is stored in physical files on disk and is transferred into memory when used.
Among them, control files, data files, redo log files, trace files and warning logs (trace files, alert files) belong to database files;
Parameter file (parameter file) and password file (password file) are non-database files

1.1 Data files: files that store data. Data files typically represent the size of an Oracle database based on the disk space and amount they use.
For performance reasons, each type of data is placed in a corresponding file or series of files, and these files are placed on different disks.
types:
.data dictionary .data
.redo data .index
.temporary data etc.
1.2 Control file: Contains the necessary information to maintain and verify the integrity of the database, for example, control The file is used to identify data files and redo log files. A database requires at least one control file.
Control file content
. Database name
. Table space information
. The names and locations of all data files
. The names and locations of all redo log files
. Current log sequence number
. Checkpoint information
. Information about the current status of redo logs and archives
Usage process of control files
Control files guide Oracle to other parts of the database file. When starting an instance, Oracle reads the name and location of the control file from the parameter file. When installing the database, Oracle opens the control file. When the database is finally opened, Oracle reads the list of data files from the control file and opens each file within them.
1.3 Redo log file: Contains records of changes made to the database, so that data recovery can be enabled in the event of a failure. A database requires at least two redo log files.
1.4 Trace Files and Alert Files (Trace Files and Alert Files)
Each background process running in the instance has a trace file (trace file) with it connected. Trace file records information about major events encountered by the background process.
Alert Log is a special tracking file. Each database has a tracking file that records database messages and errors simultaneously.
1.5 Parameter file: includes a large number of settings that affect the functionality of the Oracle database instance. Set as follows:
. The location of the database control file
. The amount of memory
used by Oracle to cache data read from disk. The default optimizer selection.

is related to the database file and performs two important functions