Chapter 5
05_data_dict_and_dynamic_view
四个重要的组件：
Data dict
performance tables
PL/SQL packages
Database event triggers
Data dict：
Central to every oracle database
desc the db and its objects
containts read-only tables and views
stored in the system tablespace
owner by the user SYS
maintained by the oracle server
accessed with select
base tables && dd views
base tables
stores desc of the db
created with create database
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sql.bsq
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Data dict views
used to simplify the base table information
accessed through public sysnonyms
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created with the catalog.sql script catproc.sql
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Data dict:
provides: logical and physical db structures
definitions and space allocations of objects
users
roles
privileges
auditing
integrity constraints
primary uses:
oracle server uses it to find information about
users
schema objects
storage structures
oracle server modifieds it when a DDL statement is executed
users and DBAs use it as a read-only reference for information about the database
DD View Catagories:
static vies
Three:
DBA_XXX
ALL_XXX
USER_XXX
Dynamic performance tables:
virtual tables
record current database activity
continually updated while the db is operational
information is accessed from memory and control file
used to monitor and tune the db
owned by the SYS user
synonyms begin with v$
listed in v$fixed_table