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This article mainly explains "what are the knowledge points of database system tables and data dictionaries". Interested friends might as well take a look. The method introduced in this paper is simple, fast and practical. Next, let the editor take you to learn "what are the knowledge points of database system tables and data dictionaries?"

1. System table

The system parameters of the ORACLE database are stored in the database, which can be queried by the user SYSYTEM through SQLPLUS. Several important tables or views are as follows:

V$controlfile: control file information

V$datafile: information for data files

V$log: information about log files

V$process: processor information

V$session: session information

V$transaction: transaction information

V$resource: resource information

V$sga: information about the global area of the system.

The 'vested characters' in the view name above are just the characters in the view name. There are many more similar to the above view or table, located in:

$ORACLE_HOME/RDBMS/ADMIN/CATALOG.SQL file.

These views or tables can be queried in SQLPLUS using a select statement.

two。 Data dictionary view

Tables and columns

DBA_TABLES, ALL_TABLES, and USER_TABLES show general information about database tables.

DBA_TAB_COLUMNS, ALL_TAB_COLUMNS, and USER_TAB_COLUMNS display information about the columns of each database table.

Note: DBA_OBJECTS, ALL_OBJECTS, and USER_OBJECTS display information about schema objects, including tables.

Integrity constraint

DBA_CONSTRAINTS, ALL_CONSTRAINTS, and USER_CONSTRAINST display general information about constraints.

DBA_CONS_COLUMNS, ALL_CONS_COLUMNS, and USER_CONS_COLUMNS display general information about column-related constraints.

View

DBA_VIEWS, ALL_VIEWS and USER_VIEWS.

Note: DBA_OBJECTS, ALL_OBJECTS, and USER_OBJECTS display information about the schema object, including the view.

Sequence

DBA_SEQUENCES, ALL_SEQUENCES and USER_SEQUENCES.

Note: DBA_OBJECTS, ALL_OBJECTS, and USER_OBJECTS display information about schema objects, including sequences.

Synonym

DBA_SYNONYMS, ALL_SYNONYMS and USER_SYNONYMS.

Note: DBA_OBJECTS, ALL_OBJECTS, and USER_OBJECTS display information about schema objects, including synonyms.

Indexes

DBA_INDEXS, ALL_INDEXS, USER_INDEXS, DBA_IND_COLUMNS, ALL_IND_COLUMNS and USER_IND_COLUMNS.

User

DBA_USERS .

Role

DBA_ROLES .

Table space quota

DBA_TS_QUOTAS .

Configuration table

DBA_PROFILES .

Tablespace

DBA_TABLESPACES .

Data file

DBA_DATA_FILES .

Segment

DBA_SEGMENTS 、 USER_SEGMENT .

Rollback segment

DBA_ROLLBACK_SEGS 、 V$ROLLNAME 、 V$ROLLSTAT .

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