1、数据字典(Data dictionary)的功能

1)   central of oracle   database               每个oracle数据库的核心

2)   describes   the  databases  and  its  objects   描述 数据库和 它所有的对象

3)   contains   read_only table and views       包括只读的表和视图

4)   owner :sys                                                       sys独有

5)   oracle server  维护,ddl操作会更新数据字典

6)  通过select 访问

7)  记录数据库的物理、逻辑结构和所有对象的定义的信息

8)  存放在system tablesapce

 2、数据字典的组成

基表-------------------------------视图--------------同义词-------User access

(x$)  (全局用于集群)               dba_XXX

(_$)                                              all_XXX

user_XXX

---可以通过trace 查看所使用的基表

3、数据字典的内容

1)    数据库的逻辑和物理的架构

2)    用户及对象的定义和存储信息

3)    权限、角色、审计等

4)    database的状态

 4、数据字典分类

静态(static) 和动态(dynami)---------------------(通过dict查看所有的数据字典的视图)

static :在数据库open状态下访问,可以通过静态视图了解database的架构(记录database的架构,object的数据定义和存储等信息)

user_:存储当前用户所拥有的对象的相关信息

all_ : 存储当前用户能够访问的对象(包括用户所拥有的对象和别的用户授权访问的对象)的信息。

dba_ :  存储所有用户对象的信息(默认只能有sys/system 用户访问)

DYNAMIC: 反映数据库当前的状态,从控制文件和内存中读出(v$视图),可以通过v$fixed_table 这个视图查到所有的动态视图的名称;

用于调优和数据库监控

v$多用于单机,GV$全局的,多用于集群环境

V$CONTROLFILE

V$DATABASE

V$DATAFILE

SYS @ prod >desc  v$fixed_table;

Name                                      Null?    Type

----------------------------------------- -------- ----------------------------

NAME                                                   VARCHAR2(30)

OBJECT_ID                                          NUMBER

TYPE                                                     VARCHAR2(5)

TABLE_NUM                                       NUMBER

SYS @ prod >select name,object_id,type  from v$fixed_table  where  rownum<6;

NAME                            OBJECT_ID TYPE

------------------------------ ---------- -----

X$KQFTA                        4294950912 TABLE

X$KQFVI                        4294950913 TABLE

X$KQFVT                        4294951149 TABLE

X$KQFDT                        4294950914 TABLE

X$KQFCO                        4294951036 TABLE

SYS @ prod >select name from v$datafile;

NAME

--------------------------------------------------------------------------------

/u01/app/oracle/oradata/prod/system01.dbf

/u01/app/oracle/oradata/prod/undotbs01.dbf

/u01/app/oracle/oradata/prod/sysaux01.dbf

/u01/app/oracle/oradata/prod/users01.dbf

/u01/app/oracle/oradata/prod/test01.dbf

/u01/app/oracle/oradata/prod/test02.dbf

/u01/app/oracle/oradata/prod/test04.dbf

V$INSTANCE

V$PARAMETER

V$SESSION

V$SGA

V$SPPARAMETER

V$TABLESPACE

V$THREAD

V$VERSION

V$TRANSACTION

V$SQLTEXT(查看SQL语句的详细内容)

SQL> select USERNAME,SID,serial# from v$session    where username is not null;                                                        ——查看当前会话信息

USERNAME               SID    SERIAL#

--------------- ---------- ----------

SYS                             39          1

SCOTT                       37          3

SQL> conn scott/tiger

SCOTT @ prod >update emp set  sal=sal/1  ;【用其他会话进行事物处理】

SQL> SELECT A.USERNAME,B.STATUS FROM V$SESSION A,V$TRANSACTION B    WHERE A.SADDR =B.SES_ADDR;

——联合V$SESSION、V$TRANSACTION查看事务处理状态

USERNAME        STATUS

--------------- ------------------------------------------------

SCOTT           ACTIVE

SQL> SELECT A.USERNAME,B.STATUS,c.sql_text FROM V$SESSION A,V$TRANSACTION B,v$sqltext c

where a.saddr=b.ses_addr and a.prev_sql_id=c.sql_id and a.username='SCOTT';        ——联合三个视图来查询

USERNAME                       STATUS           SQL_TEXT

------------------------------ ---------------- --------------------------------------------------

SCOTT                          ACTIVE           update emp set  sal=sal/1

SYS@ prod>  Desc  dict   查看数据字典

SYS@ prod>select  table_name  from dict  where  table_name like '%INDEX%';

TABLE_NAME

------------------------------

USER_INDEXES

ALL_INDEXES

DBA_INDEXES

DBA_INDEXTYPES

USER_INDEXTYPES

ALL_INDEXTYPES

DBA_INDEXTYPE_COMMENTS

USER_INDEXTYPE_COMMENTS

ALL_INDEXTYPE_COMMENTS

DBA_INDEXTYPE_ARRAYTYPES

USER_INDEXTYPE_ARRAYTYPES

ALL_INDEXTYPE_ARRAYTYPES

DBA_INDEXTYPE_OPERATORS

USER_INDEXTYPE_OPERATORS

ALL_INDEXTYPE_OPERATORS

USER_PART_INDEXES

ALL_PART_INDEXES

DBA_PART_INDEXES

DBA_XML_INDEXES

ALL_XML_INDEXES

USER_XML_INDEXES

INDEX_HISTOGRAM

INDEX_STATS

V$INDEXED_FIXED_COLUMN

GV$INDEXED_FIXED_COLUMN

查找列的注释 数据字典dict_columns

SYS@ prod>desc  dict_columns;

Name           Type                             Null?

-------------------------------------------------------------------------------------------------------------

TABLE_NAME   VARCHAR2(30)

COLUMN_NAME  VARCHAR2(30)

COMMENTS     VARCHAR2(4000)

SYS@ prod>select  column_name,comments  from dict_columns  where  table_name='DBA_TABLES';

COLUMN_NAME                    COMMENTS

------------------------------ --------------------------------------------------

BUFFER_POOL                    The default buffer pool to be used for table blocks

ROW_MOVEMENT                   Whether partitioned row movement is enabled or disabled

GLOBAL_STATS                   Are the statistics calculated without merging underlying partitions?

USER_STATS                     Were the statistics entered directly by the user?

DURATION                       If temporary table, then duration is sys$session or sys$transaction else NULL

SKIP_CORRUPT                   Whether skip corrupt blocks is enabled or disabled

MONITORING                     Should we keep track of the amount of modification?

CLUSTER_OWNER                  Owner of the cluster, if any, to which the table belongs

DEPENDENCIES                   Should we keep track of row level dependencies?

COMPRESSION                    Whether table compression is enabled or not

DROPPED                        Whether table is dropped and is in Recycle Bin

OWNER                          Owner of the table

TABLE_NAME                     Name of the table

TABLESPACE_NAME                Name of the tablespace containing the table

CLUSTER_NAME                   Name of the cluster, if any, to which the table belongs

IOT_NAME                       Name of the index-only table, if any, to which the overflow or mapping table entry belongs

STATUS                         Status of the table will be UNUSABLE if a previous

DROP TABLE operation failed,

VALID otherwise

PCT_FREE                       Minimum percentage of free space in a block

PCT_USED                       Minimum percentage of used space in a block

INI_TRANS                      Initial number of transactions

MAX_TRANS                      Maximum number of transactions

INITIAL_EXTENT                 Size of the initial extent in bytes

NEXT_EXTENT                    Size of secondary extents in bytes

MIN_EXTENTS                    Minimum number of extents allowed in the segment

MAX_EXTENTS                    Maximum number of extents allowed in the segment

PCT_INCREASE                   Percentage increase in extent size

FREELISTS                      Number of process freelists allocated in this segment

FREELIST_GROUPS                Number of freelist groups allocated in this segment

LOGGING                        Logging attribute

BACKED_UP                      Has table been backed up since last modification?

NUM_ROWS                       The number of rows in the table

BLOCKS                         The number of used blocks in the table

EMPTY_BLOCKS                   The number of empty (never used) blocks in the table

AVG_SPACE                      The average available free space in the table

CHAIN_CNT                      The number of chained rows in the table

AVG_ROW_LEN                    The average row length, including row overhead

AVG_SPACE_FREELIST_BLOCKS      The average freespace of all blocks on a freelist

NUM_FREELIST_BLOCKS            The number of blocks on the freelist

DEGREE                         The number of threads per instance for scanning the table

INSTANCES                      The number of instances across which the table isto be scanned

CACHE                          Whether the table is to be cached in the buffer cache

TABLE_LOCK                     Whether table locking is enabled or disabled

SAMPLE_SIZE                    The sample size used in analyzing this table

LAST_ANALYZED                  The date of the most recent time this table was analyzed

PARTITIONED                    Is this table partitioned? YES or NO

IOT_TYPE                       If index-only table, then IOT_TYPE is IOT or IOT_OVERFLOW or IOT_MAPPING else NULL

TEMPORARY                      Can the current session only see data that it place in this object itself?

SECONDARY                      Is this table object created as part of icreate for domain indexes?

NESTED                         Is the table a nested table?

ORACLE 存放数据都是以段的形式存放的

 

SYS@ prod>desc  dba_segments;

Name                                                                                                              Null?    Type

----------------------------------------------------------------------------------------------------------------- -------- ----------------------------------------------------------------------------

OWNER                                                                                                                      VARCHAR2(30)

SEGMENT_NAME                                                                                                               VARCHAR2(81)

PARTITION_NAME                                                                                                             VARCHAR2(30)

SEGMENT_TYPE                                                                                                               VARCHAR2(18)

TABLESPACE_NAME                                                                                                            VARCHAR2(30)

HEADER_FILE                                                                                                                NUMBER

HEADER_BLOCK                                                                                                               NUMBER

BYTES                                                                                                                      NUMBER

BLOCKS                                                                                                                     NUMBER

EXTENTS                                                                                                                    NUMBER

INITIAL_EXTENT                                                                                                             NUMBER

NEXT_EXTENT                                                                                                                NUMBER

MIN_EXTENTS                                                                                                                NUMBER

MAX_EXTENTS                                                                                                                NUMBER

PCT_INCREASE                                                                                                               NUMBER

FREELISTS                                                                                                                  NUMBER

FREELIST_GROUPS                                                                                                            NUMBER

RELATIVE_FNO                                                                                                               NUMBER

BUFFER_POOL                                                                                                                VARCHAR2(7)

SYS@ prod>select  bytes,blocks,extents,header_file,header_block,tablespace_name from dba_segments where  owner='SCOTT' and segment_name='EMP';

BYTES     BLOCKS    EXTENTS HEADER_FILE HEADER_BLOCK TABLESPACE_NAME

---------- ---------- ---------- ----------- ------------ ------------------------------

65536          8                1                     4                        27                        USERS

查看 表的大小 系统为 emp 这张表 分配了64K的存储空间  1个区  8个块    段头在第4个文件  第27个数据块

SYS@ prod>desc  dba_extents;

Name                                                                                                              Null?    Type

----------------------------------------------------------------------------------------------------------------- -------- ----------------------------------------------------------------------------

OWNER                                                                                                                      VARCHAR2(30)

SEGMENT_NAME                                                                                                               VARCHAR2(81)

PARTITION_NAME                                                                                                             VARCHAR2(30)

SEGMENT_TYPE                                                                                                               VARCHAR2(18)

TABLESPACE_NAME                                                                                                            VARCHAR2(30)

EXTENT_ID                                                                                                                  NUMBER

FILE_ID                                                                                                                    NUMBER

BLOCK_ID                                                                                                                   NUMBER

BYTES                                                                                                                      NUMBER

BLOCKS                                                                                                                     NUMBER

RELATIVE_FNO                                                                                                               NUMBER

SYS@ prod>select file_id,block_id ,blocks  from dba_extents where owner='SCOTT' and segment_name='EMP';

FILE_ID   BLOCK_ID     BLOCKS

---------- ---------- ----------

4         25          8

SCOTT@ prod>select  rowid  from  emp;

ROWID

------------------

AAAMfMAAEAAAAAgAAA

AAAMfMAAEAAAAAgAAB

AAAMfMAAEAAAAAgAAC

AAAMfMAAEAAAAAgAAD

AAAMfMAAEAAAAAgAAE

AAAMfMAAEAAAAAgAAF

AAAMfMAAEAAAAAgAAG

AAAMfMAAEAAAAAgAAH

AAAMfMAAEAAAAAgAAI

AAAMfMAAEAAAAAgAAJ

AAAMfMAAEAAAAAgAAK

AAAMfMAAEAAAAAgAAL

AAAMfMAAEAAAAAgAAM

AAAMfMAAEAAAAAgAAN

SYS@ prod>desc  dba_tablespaces;

Name                                                              Null?    Type

----------------------------------------------------------------- -------- --------------------------------------------

TABLESPACE_NAME                                                   NOT NULL VARCHAR2(30)

BLOCK_SIZE                                                        NOT NULL NUMBER

INITIAL_EXTENT                                                             NUMBER

NEXT_EXTENT                                                                NUMBER

MIN_EXTENTS                                                       NOT NULL NUMBER

MAX_EXTENTS                                                                NUMBER

PCT_INCREASE                                                               NUMBER

MIN_EXTLEN                                                                 NUMBER

STATUS                                                                     VARCHAR2(9)

CONTENTS                                                                   VARCHAR2(9)

LOGGING                                                                    VARCHAR2(9)

FORCE_LOGGING                                                              VARCHAR2(3)

EXTENT_MANAGEMENT                                                          VARCHAR2(10)

ALLOCATION_TYPE                                                            VARCHAR2(9)

PLUGGED_IN                                                                 VARCHAR2(3)

SEGMENT_SPACE_MANAGEMENT                                                   VARCHAR2(6)

DEF_TAB_COMPRESSION                                                        VARCHAR2(8)

RETENTION                                                                  VARCHAR2(11)

BIGFILE                                                                    VARCHAR2(3)

SYS@ prod>select  tablespace_name,block_size,status ,logging  from dba_tablespaces;

TABLESPACE_NAME                BLOCK_SIZE STATUS    LOGGING         修改数据 是否会产生日志

------------------------------ ---------- --------- ---------

SYSTEM                               8192 ONLINE    LOGGING

UNDOTBS1                             8192 ONLINE    LOGGING

SYSAUX                               8192 ONLINE    LOGGING

TEMP                                 8192 ONLINE    NOLOGGING

USERS                                8192 ONLINE    LOGGING

EXAMPLE                              8192 ONLINE    NOLOGGING

动态性能视图

虚拟的表

记录当前数据库的统计信息   操作

当数据库被修改的时候  记录操作信息

从控制文件和内存收集信息

Sys 用户独有

v$开头的同义词

v$_       gv$_    开头的都是视图

SYS@ prod>desc  v_$log;    此乃 基表

Name                                                              Null?    Type

----------------------------------------------------------------- -------- --------------------------------------------

GROUP#                                                                     NUMBER

THREAD#                                                                    NUMBER

SEQUENCE#                                                                  NUMBER

BYTES                                                                      NUMBER

MEMBERS                                                                    NUMBER

ARCHIVED                                                                   VARCHAR2(3)

STATUS                                                                     VARCHAR2(16)

FIRST_CHANGE#                                                              NUMBER

FIRST_TIME                                                                 DATE

SYS@ prod>desc  v$log;    此乃对应的 视图

Name                                                              Null?    Type

----------------------------------------------------------------- -------- --------------------------------------------

GROUP#                                                                     NUMBER

THREAD#                                                                    NUMBER

SEQUENCE#                                                                  NUMBER

BYTES                                                                      NUMBER

MEMBERS                                                                    NUMBER

ARCHIVED                                                                   VARCHAR2(3)

STATUS                                                                     VARCHAR2(16)

FIRST_CHANGE#                                                              NUMBER

FIRST_TIME                                                                 DATE

以下视图同上

V$controlfile

V$datafile

V$database

V$instance

V$parameter

V$session

V$sga

SYS@ prod>Show  parameter cache;

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

db_16k_cache_size                    big integer 0

db_2k_cache_size                     big integer 0

db_32k_cache_size                    big integer 0

db_4k_cache_size                     big integer 0

db_8k_cache_size                     big integer 0

db_cache_advice                      string      ON

db_cache_size                        big integer 0

db_keep_cache_size                   big integer 0

db_recycle_cache_size                big integer 0

object_cache_max_size_percent        integer     10

object_cache_optimal_size            integer     102400

session_cached_cursors               integer     20

SYS@ prod>desc  v$parameter;

Name                                                              Null?    Type

----------------------------------------------------------------- -------- --------------------------------------------

NUM                                                                        NUMBER

NAME                                                                       VARCHAR2(80)

TYPE                                                                       NUMBER

VALUE                                                                      VARCHAR2(512)

DISPLAY_VALUE                                                              VARCHAR2(512)

ISDEFAULT                                                                  VARCHAR2(9)

ISSES_MODIFIABLE                                                           VARCHAR2(5)

ISSYS_MODIFIABLE                                                           VARCHAR2(9)

ISINSTANCE_MODIFIABLE                                                      VARCHAR2(5)

ISMODIFIED                                                                 VARCHAR2(10)

ISADJUSTED                                                                 VARCHAR2(5)

ISDEPRECATED                                                               VARCHAR2(5)

DESCRIPTION                                                                VARCHAR2(255)

UPDATE_COMMENT                                                             VARCHAR2(255)

HASH                                                                       NUMBER

SYS @ prod >desc v$session;

Name                                                              Null?    Type

----------------------------------------------------------------- -------- --------------------------------------------

SADDR                                                                      RAW(4)

SID                                                                        NUMBER

SERIAL#                                                                    NUMBER

AUDSID                                                                     NUMBER

PADDR                                                                      RAW(4)

USER#                                                                      NUMBER

USERNAME                                                                   VARCHAR2(30)

COMMAND                                                                    NUMBER

OWNERID                                                                    NUMBER

TADDR                                                                      VARCHAR2(8)

LOCKWAIT                                                                   VARCHAR2(8)

STATUS                                                                     VARCHAR2(8)

SERVER                                                                     VARCHAR2(9)

SCHEMA#                                                                    NUMBER

SCHEMANAME                                                                 VARCHAR2(30)

OSUSER                                                                     VARCHAR2(30)

PROCESS                                                                    VARCHAR2(12)

MACHINE                                                                    VARCHAR2(64)

TERMINAL                                                                   VARCHAR2(30)

PROGRAM                                                                    VARCHAR2(48)

TYPE                                                                       VARCHAR2(10)

SQL_ADDRESS                                                                RAW(4)

SQL_HASH_VALUE                                                             NUMBER

SQL_ID                                                                     VARCHAR2(13)

SQL_CHILD_NUMBER                                                           NUMBER

PREV_SQL_ADDR                                                              RAW(4)

PREV_HASH_VALUE                                                            NUMBER

PREV_SQL_ID                                                                VARCHAR2(13)

PREV_CHILD_NUMBER                                                          NUMBER

MODULE                                                                     VARCHAR2(48)

MODULE_HASH                                                                NUMBER

ACTION                                                                     VARCHAR2(32)

ACTION_HASH                                                                NUMBER

CLIENT_INFO                                                                VARCHAR2(64)

FIXED_TABLE_SEQUENCE                                                       NUMBER

ROW_WAIT_OBJ#                                                              NUMBER

ROW_WAIT_FILE#                                                             NUMBER

ROW_WAIT_BLOCK#                                                            NUMBER

ROW_WAIT_ROW#                                                              NUMBER

LOGON_TIME                                                                 DATE

LAST_CALL_ET                                                               NUMBER

PDML_ENABLED                                                               VARCHAR2(3)

FAILOVER_TYPE                                                              VARCHAR2(13)

FAILOVER_METHOD                                                            VARCHAR2(10)

FAILED_OVER                                                                VARCHAR2(3)

RESOURCE_CONSUMER_GROUP                                                    VARCHAR2(32)

PDML_STATUS                                                                VARCHAR2(8)

PDDL_STATUS                                                                VARCHAR2(8)

PQ_STATUS                                                                  VARCHAR2(8)

CURRENT_QUEUE_DURATION                                                     NUMBER

CLIENT_IDENTIFIER                                                          VARCHAR2(64)

BLOCKING_SESSION_STATUS                                                    VARCHAR2(11)

BLOCKING_INSTANCE                                                          NUMBER

BLOCKING_SESSION                                                           NUMBER

SEQ#                                                                       NUMBER

EVENT#                                                                     NUMBER

EVENT                                                                      VARCHAR2(64)

P1TEXT                                                                     VARCHAR2(64)

P1                                                                         NUMBER

P1RAW                                                                      RAW(4)

P2TEXT                                                                     VARCHAR2(64)

P2                                                                         NUMBER

P2RAW                                                                      RAW(4)

P3TEXT                                                                     VARCHAR2(64)

P3                                                                         NUMBER

P3RAW                                                                      RAW(4)

WAIT_CLASS_ID                                                              NUMBER

WAIT_CLASS#                                                                NUMBER

WAIT_CLASS                                                                 VARCHAR2(64)

WAIT_TIME                                                                  NUMBER

SECONDS_IN_WAIT                                                            NUMBER

STATE                                                                      VARCHAR2(19)

SERVICE_NAME                                                               VARCHAR2(64)

SQL_TRACE                                                                  VARCHAR2(8)

SQL_TRACE_WAITS                                                            VARCHAR2(5)

SQL_TRACE_BINDS                                                            VARCHAR2(5)

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