Oracle architecture Diagram

This section describes the architecture of oracle. Oracle Systems mainly include instance instances and database databases.

Instance: it can be divided into PGA (process globe area) and SGA (system globe area ).

PGA is divided into user process and server process

SGA is divided into share pool, large pool, Java pool, redolog buffer, and database buffer cache.

Share pool: Library cache and data dictionary cache. Library cache is used to store SQL and PL/SQL objects. There are also tables and indexes.

Data dictionarycache: used to store data dictionaries, including permission verification.

Java pool: This part of memory is used when some java operations are executed.

Large pool: the memory of the large pool is generally used for database RMAN backup or data recovery.

Database buffer cache: the main memory space used to store executed SQL statements. We need to increase the hit rate of the memory storage structure.

Redolog Buffer: as its name implies, it is used to store online log information of some redo logs. When performing some operations. This information is written to the redo log file.

Database Data File: data file control file online archiving log redo log file archiving log file: archivle log files

Parameter file spfile, pfile Password File

For DBF, CTL, and redolog files, the default storage path is in the path $ oracle_base/oradata/orcl/. suer. We can select * from V $ logfile;
View the loffile location. You can view it through show parameter control_file. For the location of the DBF file, we can use select name Form V $ datafile
View.

You can use show parameter spfile to view the parameter file under $ oracle_base/products/10.0.2/dbs/by default.

The password file is in the path $ oracle_base/products/10.0.2/dbs/by default.

You can use show parameter log_archive_dest to view archive logs.

For background processes that connect to databases and instances, SMON, pmon, dbwn, lgrw, ckpt, etc.