Brief description of ORACLE data dictionary and dynamic performance View

 

1. Data Dictionary

The Data Dictionary of Oracle Data is composed of base tables and data dictionary views.

It is usually read-only for users.

Stored in system tablaspace

User SYS

For users, only select

 

The base table is generated by calling the script $ ORACLE_HOME/rdbms/admin/SQL. bsq when the database is created.

The data dictionary view is generated by the script $ ORACLE_HOME/rdbms/admin/CATALOG. SQL.

 

Data Dictionary views can be divided into three types: DBA _ *, all _ *, and user _*

 

For DBA _*
DBS are required to include all data sets.

All ofthe objects in the database

For all _*
Package all data sets that the current user can see

Objectsaccessible by the current user

For user _*
Only the sechemas of the current user

Objects owned by the current user

 

All base tables exist in the dictionary table,

You can use selecttable_name from dictionary where table_name like 'dba % 'to query related base tables.

Commonly used base tables dba_users, dba_data_files, dba_tablespace, dba_objects, dba_tables, dba_indexes

Dba_tab_columns, dba_constraints

 

2. Dynamic View

A is a virtual table.

B records the activity indicators of the current database.

C. perform operations on the database in real time.

D. control access to some data in files and memory.

E belongs to SYS user

F starts with V $

G. All the resumed tables have V $ fixed_table.

 

Common dynamic performance View

V $ controlfile

V $ Database

V $ datafile

V $ instance

V $ Parameter

V $ session

V $ SGA

V $ spprameter

V $ tablespace

V $ thread

V $ version

For the parameter view in the memory, V $ Parameter
Another frequently used form is

Show parameter SGA
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