Tablespace mgmt in 10g.pdf

8/10/2019 Tablespace mgmt in 10g.pdf

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MANAGING TABLESPACES IN ORACLE 10g

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

LOGICAL STORAGE STRUCTURES

The logical units of database space allocation are data blocks, extents, segments,

tablespaces. At a physical level the data is stored in data files (disk).

Tablespaces Segments Extents Blocks

Physically Oracle stores everything in file, called data files. Physical storage is

how Oracle stores the data physically in the system. Whereas logical storage

talks about how an end user actually accesses that data. The logical structures

are created and recognized by Oracle and are not known to the OS.

Tablespaces are divided into logical units of storage called SEGMENTS.

Segments are further divided into EXTENTS.

Extents are a collection of contiguous BLOCKS.


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****

INTRODUCTION TO TABLESPACES

LOGICALstorage units called as tablespaces. It is a logical storage container for

segments. Segments are database objects, such as tables & indexes that

consume storage space.

A tablespace is a logical group of one or more data files in a database. It is logical

because a tablespace is not visible in the oracle file system. Oracle database can

contain multiple tablespaces, It can be ONLINE (accessible) or OFFLINE (not

accessible)whenever the database is open. The SYSTEM and TEMPORARY

tablespaces can NOT be taken offline. Oracle database must have system &

sysaux tablespaces.

Oracle stores data logically in TABLESPACES & physically in DATAFILES

(oslevel) associated with the corresponding tablespace. Tablespaces can be

either SMALLFILE TABLESPACES or BIGFILE TABLESPACES.


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Three different types of Tablespaces

PERMANENT TEMPORARY UNDO

When a database is created, following tablespaces are created by DBCA.

SYSTEM SYSAUX TEMP UNDOTBS1 USERS


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EXTENT MANAGEMENT OF TABLESPACES

DICTIONARY MANAGED Vs. LOCALLY MANAGED

Prior to oracle database 8i, EXTENT management was always controlled by

data dictionary tables. Oracle 8i introduced a new method of extent

management called LOCALLY MANAGED TABLESPACES (LMT).

When oracle allocates space to a segment (like a table or index), a group of

contiguous free blocks, called an extent, is added to the segment. Metadata

regarding extent allocation and unallocated extents are either stored in the data

dictionary, or in the tablespace itself.

Tablespaces that record extentallocation in the data dictionary, are called

DICTIONARY MANAGED. Tablespaces that record extentallocation in the

tablespace (datafile) header, are called LOCALLY MANAGED. DMT is an

obsolete Technology. AlwaysLMT is superior to DMT in every respect.


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DBA need to create tablespaces with EXTENT management defined as

either DICTIONARY or LOCAL. Tablespaces can use any one method to

keep track of free and used space. (dictionary or locally) managed.

SPACE MANAGEMENT

Oracle maintains extents for a tablespace.

Two different methods for oracle to keeping of free and used extents.

They are dictionary managed tablespace & locally managed tablespace.

DICTIONARY MANAGED TABLESPACES

Oracle use the data dictionary (tables in SYS schema) to track allocated and

free extents for tablespaces that is in " DICTIONARY MANAGED" mode.

Oracle updates the following tables in the data dictionary whenever an

extent is allocated, or freed for reuse.

Free space is recorded in the SYS.FET$ table.

Used space in the SYS.UET$ table.

CREATING DICTIONARY MANAGED TABLESPACE

SQL> create tablespace test datafile '/u01/test01.dbf' size 10m

Extent management DICTIONARY;

SQL> select tablespace_name, extent_management from

dba_tablespaces where tablespace_name=TEST;

TABLESPACE_NAME EXTENT_MANAGEMENT

TEST DICTIONARY
http://oracletipstricks.blogspot.in/2007/09/locally-vs-dictionary-managed.htmlhttp://oracletipstricks.blogspot.in/2007/09/locally-vs-dictionary-managed.htmlhttp://oracletipstricks.blogspot.in/2007/09/locally-vs-dictionary-managed.html


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ORA - 12913

Lets check SYS.FET$ view to tablespace TEST (dictionary managed ).

SQL> select * from SYS.FET$ where ts#='6'; (test tablespace).

TS# FILE# BLOCK# LENGTH

6 4 2 1279

SQL> create table tab1(no number , name varchar(10));

Table created.

SQL> begin

2 for i in 1..10000 loop

3 insert into tab1 values (i, 'sam');

4 end loop;

6 end;

7 /

PL/SQL procedure successfully completed.


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Lets check SYS.UET$ view to tablespace TEST (dictionary managed).

SQL> select SEGBLOCK#, EXT#, FILE#, BLOCK#, LENGTH, SEGBLOCK#

from SYS.UET$ where ts#='8';

SEGBLOCK# EXT# FILE# BLOCK# LENGTH SEGBLOCK#

2 0 4 2 5 2

2 1 4 7 5 2

2 2 4 12 10 2

STORAGE PARAMETERS

The storage parameters are NOT valid if extents that are managed locally.

NEXT, INITIAL, PCTINCREASE ,

MINEXTENTS, MAXEXTENTS, DEFAULT STORAGE

Initial Extent Default initial extent size

Next Extent Default incremental extent size

Min Extents Default minimum number of extents

Max Extents Default maximum number of extents

PCT Increase Default percent increase for extent size

SQL>select initial_extent, min_extents, max_extents, next_extent ,

pct_increase from dba_tablespaces where tablespace_name=TEST;

INITIAL_EXTENT MIN_EXTENTS MAX_EXTENTS NEXT_EXTENT PCT_INCREASE

40960 1 505 40960 50


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ADVANTAGES OF LOCALLY MANAGED TABLESPACES

Do NOT record free space in data dictionary, it reduces contention on these

tables. LMT of extents automatically tracks adjacent free space.

Oracle is managing extents by maintaining a bitmap in each datafile to keep track

of the free or used status of blocks in datafile. Each bit in the bitmap corresponds

to a block or a group of blocks. When the extents are allocated or freed for reuse,

Oracle simply changes the bitmap values to show the new status of the blocks.

Eliminates the need for recursive SQL operations against the data dictionary

(UET$&FET$tables). Reduce contention on data dictionary tables. Locally

managed tablespaces eliminate the need to periodically coalesce free space

(automatically tracks adjacent free space)

POINTS TO REMEMBER

A dictionary tablespace can be changed into a locally managed but a

locally manged tablespace cannot be changed into a dictionary one.

If the SYSTEMtablespace is locally managed only create locally managed

tablespaces , trying to create a dictionary one will fail.

DBA CAN USE TABLESPACES TO DO THE FOLLOWING ACTIONS

Create new table spaces & data files to table spaces.

Make a table space read only or read/write.

Make a table space temporary or permanent.

Rename , Relocate table spaces & drop table spaces.


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MIGRATING DMT TO LMT ( USERS TABLESPACE )

SQL> select tablespace_name , extent_management from dba_tablespaces ;

TABLESPACE_NAME EXTENT_MAN

SYSTEM DICTIONARY

SYSAUX LOCAL

TEMP LOCAL

USERS DICTIONARY

SQL> execute dbms_space_admin.tablespace_migrate_to_local(XXXX);

SQL> exec dbms_space_admin.tablespace_migrate_to_local(TEST);


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CONVERTING LMT TO DMT

SQL>execute dbms_space_admin.tablespace_migrate_from_local(XXXX);

SQL>exec dbms_space_admin.tablespace_migrate_to_local(TEST);

PL/SQL procedure successfully completed.

If we create a database with DBCA , it will have a locally managed SYSTEM

tablespace by default. we cannot create new dictionary managed tablespaces.

Sizes of extents that are managed locally can be determined automatically by

the system. Alternatively, all extents might be the same size in a LMT. If we

want to create extents with the same sizes, you need to specify UNIFORM.

Changes to the extent bitmaps do NOT generate rollback information because

they do NOT update tables in the data dictionary (except for special cases such

as tablespace quota information). Reduced fragmentation.


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As I said , see the keyword "autoallocate" why extents are allocated with

different sizes as autoallocatespecifies extentsizes are system generated. Most

likely our tablespace will be autoalloctate LMT.

Who wants to create extents with the same sizes, need to specify UNIFORM.


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Lets start with two users . Each user is assigned different , different

tablespace. User ROSE is assigned to test tablespace(uniform). User SONA

is assigned to samp tablespace (autoallocate).


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When creating tablespace samp , I did NOT mention UNIFORMso extents

sizes are NOT same. We can see bytes column from following screen shot.


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TO FIND TABLESPACE PARAMS

I am attaching screen shot for both tablespaces ( test&

samp).

SQL> SELECT tablespace_name

, contents

, extent_management

, allocation_type

, segment_space_management

FROM dba_tablespaces ;

SQL> select tablespace_name, contents, status, block_size, initial_extent,

extent_namagement, allocation_type, segment_space_management,

bigfile from dba_tablespaces ;


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LMT can use either autoallocate or uniform is all about allocation of new

extents when space pressure increases in the tablespace

UNIFORMLY SIZED EXTENTS - UNIFORM

AUTO SIZED EXTENTS -AUTOALLOCATE

AUTO ALLOCATE

Means that the extent sizes are managed by Oracle. It will choose the optimal

next size for the extents starting with 64 KB. As the segments grow and more

extents are needed, Oracle starts allocating larger and larger sizes then it moves

to 1Mb , 8MB ultimately to 64Mb extents. We can make initial extent size of

greater than 64KB , it will allocate extents atleast the amount of the space.


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UNIFORM

Create the extents the same size by specifying the size when create the

tablespace. i.e. UNIFORM specifies that the tablespace is managed with

uniform extents of SIZEbytes (use Kor Mto specify the extent size).

When the SYSTEMtablespace is dictionarymanaged other tablespaces can bemanaged either LOCALLY (LM) or DICTIONARY (DM). Extent management on

the SYSAUX & UNDO tablespaces is always LOCAL.

When using auto allocateSpace allocation is simplified, because

when AUTOALLOCATE is specified, i.e. database automatically selects the

appropriate extent size. Space allocations and deallocations modify locally

managed resources (bitmaps stored in header files).


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MANAGING TABLESPACE

CREATE TABLESPACE

SYNTAX - CREATING A NEW TABLESPACE

SQL> create tablespace datafile filepath size m ;

SQL> create tablespace TEST datafile 'test01.ora' size 10m;

SQL> create tablespace TEST datafile /u01/oradata/test02.orasize 15m;

Tablespace created.

If path is not specified, by default it is located at dbsdirectory

ALTER TABLESPACE

SYNTAX - ADDING A NEW DATAFILE

SQL> alter tablespace add datafile filepath size m;

SQL> alter tablespace TEST add datafile 'test03.dbf' size 10m;

SQ> alter tablespace TEST add datafile

'/u01/app/oracle/oradata/samp/test04.dbf' size 10m;

Tablespace altered.

SYNTAX - RESIZING THE EXSISTING DATAFILE

SQL> alter database datafile filepath resize m;

SQL> alter database datafile 'test01.dbf' resize 20m;

Datbase altered


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DROP TABLESPACE

SYNTAX - DROP THE TABLESPACE

SQL> drop tablespace ;

SQL> drop tablespace INCLUDING CONTENTS;

SQL> drop tablespace INCLUDING CONTENTS AND DATAFILES;

SQL> drop tablespace test;

SQL> drop tablespace test including contents;

SQL> drop tablespace test including contents and datafiles;

Tablespace dropped.

RENAME TABLESPACE

SYNTAX RENAMING A EXISTING TABLESPACE

SQL>alter tablespace rename to ;

SQL> alter tablespace TEST rename to TESTS;

Tablespace altered.

RENAMING DATAFILE

SQL> shutdown normal;

linux> mv 'OLDFILE.DBF ' 'NEWFILE.DBF'

SQL> startup mount;

SQL> alter database RENAME file 'old file path' to 'newfile path'

Database altered

SQL> alter database open;

Database opened.


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II) SYNTAX

SQL>alter database RENAME FILE old filepath to 'newfilepath;

SQL>alter database rename file /u01/app/test.dbfto /u01/test.dbf;

Database altered.

CREATING DICTIONARY MANAGED TABLESPACE

SYNTAX

SQL>create tablespace datafile 'file path ' size m

extent management DICTIONARY;

SQL> create tablespace samp datafile '/u01/oradata/samp/samp01. dbf '

size 10m extent management dictionary ;

Tablespace created.

In 10g , If not specified Extent management dictionary automatically

tablespace will be created as LOCALLY MANAGED .


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SYSTEM tablespace should be DICTIONARY MANAGED otherwise cannot

create dictionary managed tablespaces.

As far as I remember, dbcacreates databases with locally managed databases,

when creating database manually In release 10.x, the default was dictionary

managed. Locally managed tablespaces are much more efficient than dictionary

managed ones.

LOCALLY MANAGED TABLESPACE

SYNTAX CREATE LOCALLY MANAGED TABLESPCE

SQL> create tablespace datafile filepathf' size m

extent management LOCAL;

SQL>create tablespace samp datafile

'/u01/app/oracle/oradata/samp/samp01 .dbf' size 20m

extent management local;

Tablespace created.


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SYNTAX - LOCALLY MANAGED TABLESPACE USING AUTO

SQL> create tablespace datafile 'file path' size m

extent management LOCAL AUTO ALLOCATE;

SQL> create tablespace samp datafile '/u01/oradata/samp/samp02.dbf

size 10m extent management local autoallocate;

SYNTAX - LOCALLY MANAGED TABLESPACE USING UNIFORM

SQL> create tablespace datafile 'file path' size m

extent management LOCAL UNIFORM SIZE 120K;

SQL> create tablespace samp datafile '/u01/oradata/samp03.dbf'

size 20m extent management local uniform size 120k ;

TABLESPACE SPECIFYING SEGMENT SPACE ( ASSM )

SQL>create tablespace datafile 'file path'size m

extent management LOCAL segment space management AUTO;

SQL> create tablespace test datafile '/u01/oradata/samp/test01.dbf' size

15m extent management local -- ENABLE LMT

segment space management auto ; -- ENABLE ASSM

*******

ASSM takes total control of the parameters FREELISTS, FREELIST GROUPS, &

PCTUSED. Oracle will track and manage the used and free space in data blocks

using bitmaps for all objects defined in the tablespace.


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*************

LMT WITH AUTO EXTEND

EXAMPLE -I

SQL> create tablespace datafile filepath size m

AUTOEXTEND ON:

SQL> create tablespace test datafile '/u01/oradata/samp/test02.ora' size

10m autoextend on;

EXAMPLE II


AUTOEXTEND ON MAXSIZE m;


10m autoextend on maxsize 100m;

EXAMPLE III


AUTOEXTEND ON NEXT m MAXSIZE m;

SQL> create tablespace test datafile '/u01/oradata/samp/test04.ora'

size 10m autoextend on next 2m maxsize 100m;

EXAMPLE IV


AUTOEXTEND ON MAXSIZE UNLIMITED.


10m autoextend on maxsize 100m;


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EXAMPLE - V

SQL> create tablespace add datafile filepath size

mAUTOEXTEND ON MAXSIZE UNLIMITED

SQL> create tablespace test datafile '/u01/oradata/samp/test05.ora'

size 10m autoextend on maxsize unlimited;

EXAMPLE - VI

SQL> alter database datafile filepath AUTOEXTEND ON

MAXSIZE UNLIMITED ;

SQL> alter database test datafile '/u01/oradata/samp/test05.ora'

autoextend on maxsize unlimited;

EXAMPLE - VII

SQL>alter database datafile 'pathfile' AUTOEXTEND OFF;

SQL>alter database datafile '/u01/oradata/samp/test04.dbf'

autoextend off;

TO CHECK AUTO EXTENSIBLE STATUS

SQL> select file_name, autoextensible from dba_data_files

where tablespace_name like '%TES%';

ASSIGNING A DEFAULT TABLESPACE FOR WHOLE DATABASE

SQL>alter database default tablespace ;

SQL>alter database default tablespace sample;*****************


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CHECKING DEFAULT TABLESPACES IN DATABASE

ASSIGNING TABLESPACE TO A SPECIFIC USER

SQL> alter user default tablespace ;

SQL> alter user san default tablespace users;

TO FIND DEFAULT TABLESPACES FOR SPECIFIC USERS

SQL> select username , default_tablespace from dba_users

where username='SAM' or username='SAN';

USERNAME DEFAULT_TABLESPACE

SAN USERS

SAM SAMP

ALTERING TABLESPACE AVAILABILITY

SQL>alter tablespace read only;

SQL>alter tablespace sample read only


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SQL>alter tablespace read write;

SQL>alter tablespace sample read write

SQL>alter tablespace offline;

SQL>alter tablespace sample offline;

SQL>alter tablespace online;

SQL>alter tablespace sample online;

CHECKING TABLESPACE STATUS

SOME RESTRICTIONS IMPOSED ON TABLESPACES.

TABLESPACE OFFLINE RENAME DROP

SYSTEM NO NO NO

SYSAUX YES NO NO

TEMPORARY NO YES NO

UNDO NO YES YES


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CHECKING DATAFILES BYTES , BLOCKS IN DATABASE

CHECKING DATAFILES UNDER ANYONE TABLESPACE

CHECKING DATAFILE FILE_ID , BYTES , FILE_NAME UNDER TABLESPACE


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RESIZING DATAFILE USING FILE_ID

SQL> alter database datafile resize m;

SQL>alter database datafile 4 resize 25m;

GET PROPERTIES OF AN EXISTING TABLESPACE

SQL> select DBMS_METADATA.GET_DDL('TABLESPACE', ' tsname') from dual;

SQL> select DBMS_METADATA.GET_DDL('TABLESPACE', ' USERS') from dual;

ASSIGNING QUOTAS TO A USER IN DEFAULT TABLESPACE

SQL> alter user default tablespace

quota m on ;

SQL> alter user sam default tablespace sample quota 2m on sample;

SET DEFAULT TABLESPACE TYPE

SQL>alter database set default tablespace;

SQL>alter database set default SMALLFILE tablespace;

SQL>alter database set default BIGFILE tablespace;

DISPLAY DEFAULT TABLESPACE TYPE

SQL> select property_value from database_properties

where property_name = 'DEFAULT_TBS_TYPE';

PROPERTY_VALUE

It will show what already set smallfile or bigfile.


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FIND DEFAULT_PERMANENT_TABLESPACE

SQL>select property_value from database_properties

where property_name='DEFAULT_PERMANENT_TABLESPACE';

CAN WE DROP PERMANENT TABLESPACE


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PERMANENT TABLESPACE

Permanaent tablespaces can be either small tablespacesorbig tablespaces.

Small tablespace can be made up of a number of data files. Big tablespace will

only be made up of one data file and this can get extremely large. We cannot

add datafile to a bigfile tablespace.

A bigfile tablespace with 8K blocks can contain a 32 terabyte datafile. A bigfile

tablespace with 32K blocks can contain a 128 terabyte datafile. The maximum

number of datafiles in an Oracle Database is limited (usually to 64K files). We

can specify SIZE in kilobytes (K), megabytes (M), gigabytes (G), or terabytes (T).

Bigfile tablespaces are supported only for locally managed tablespaces with

automatic segment space management.


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TEMPORARY TABLESPACES

CREATING LOCALLY MANAGED TEMPORARY TABLESPACE

SQL>create temporary tablespace TEMPFILE file path size

m EXTENT MANAGENT LOCAL;

SQL>create temporary tablespace temptbs tempfile

'/u01/app/oracle/oradata/orc/temp01.ora' size 20m

Extent management local;

ADDING TEMPFILE TO TEMPORARY TABLESPACE

SQL>alter tablespace add tempfile file path size m;

SQL>alter tablespace temptbs add tempfile

'/u01/app/oracle/oradata/orcl/temp02.ora' size 8m;

RESIZING A TEMPORARY FILE

SQL>alter database TEMPFILE file path resize m;

SQL>alter database tempfile

'/u01/app/oracle/oradata/orcl/temp02.ora' resize 15m;

HOW TO ASSIGN DEFAULT TEMPORARY TABLESPACE

SQL> alter database DEFAULT temporary tablespace

SQL> alter database default temporary tablespace temp;


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TEMPFILES AND ASSOCIATED TEMPORARY TABLESPACE

CHECKING LOCAL MANAGED TEMPFILES AND STATUS

MAKING TEMPORARY TABLESPACE TO OFFLINE

SQL>alter tablespace TEMPFILE OFFLINE;

SQL>alter tablespace TEMPTBS TEMPFILE OFFLINE ;


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ORA-12905

The DEFAULT TEMPORARY TABLESPACE cannot be taken off-line

The DEFAULT TEMPORARY TABLESPACE cannot be dropped until create

another one. We cannot change a default temporary tablespace into a

permanent tablespace. Oracle10gintroduced new feature which we will create

the temp file automatically when we restart the database.

If we make Temporary tablespace goes offline, associated all temp files will be

offline status. Even if tablespace is offline , can add temp file under this

tablespace by default ONLINE status. Even a tablespace is offline, can set

temporary tablespace as Default temporary tablespace.


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ALTERING TEMPORARY TABLESPACE TO ONLINE

SQL>alter tablespace TEMPFILE ONLINE;

SQL>alter tablespace tmpbs tempfile online;

CREATING TEMPORARY TABLESPACE AND GROUP

SQL> create temporary tablespace tempfile

filepath' size m tablespace GROUP ;

SQL> create temporary tablespace temtbs tempfile

'/u01/app/oracle/oradata/orcl/temp01.ora' size 2m

tablespace GROUP T1;

ORA-10918:

TABLESPACE GROUP name cannot be the same as tablespace name.

CREATING GROUP FOR EXISTING TEMPORARY TABLESPACE

SQL> alter tablespace tablespace GROUP ;

SQL> alter tablespace temp tablespace group t2;


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Here tmpts1 is created by oracle. If NO group exists oracle will create it.

TEMPORARY TABLESPACE WITH ASSOCIATED GROUP

SQL>select * from DBA_TABLESPACE_GROUPS;

DROPPING TEMPORARY TABLESPACE

SQL> drop tablespace including contents and datafiles;

SQL>drop tablespace tmpts including contents and datafiles;

REMOVE A TABLESPACE FROM A GROUP

SQL> alter tablespace tablespace group '';

SQL> alter tablespace tmpts tablespace group '';

QUERY TO FIND DEFAULT TEMPORARY TABLESPACE

SQL> select property_value from database_properties where

property_name = 'DEFAULT_TEMPORARY_TABLESPACE';


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SQL>select property_value from database_properties where

property_name = 'DEFAULT_TEMPORARY_TABLESPACE';

PROPERTY_VALUE

TEMP

V$SORT_SEGMENT

It contains information about every sort segment in TEMP TABLESPACE. This

view is only updated when the tablespace is of the temporarytype. We can

check total_extents , extent_size, total_blocks, free_extents, free_blocks from

v$sort_segment view.

SQL> select * from V$SORT_SEGMENT;


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DISPLAY FREE TEMP SPACE

V$TEMP_SPACE_HEADER

SQL> select sum(bytes_used), sum(bytes_free)

from v$temp_space_header group by tablespace_name;

MAKE USER USE TEMP GROUP

SQL> alter user temporary tablespace ;

SQL> alter user sam temporary tablespace t3;

The DBA should assign a temporary tablespace to each user in the database to

prevent them from allocating sort space in the SYSTEM tablespace.


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UNDO TABLESPACES

Undo tablespaces are used to store original data after it has been changed.

We can create more than one undo tablespace, but one of them can be

active at any one time. Oracle provides a fully automated mechanism, referred

to as automatic undo management, for managing undo information and space.

AUM (AUTOMATIC UNDO MANAGEMENT)

CREATING UNDO TABLESPACE

SQL> create UNDO tablespace datafile filepath' size m;

RESIZING UNDO TABLESPACE

SQL> alter database datafile pathfile resize m;


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ADDING DATAFILE TO UNDO TABLESPACE

SQL> alter tablespace add filepath size m;

TO FIND CURRENTLY USED UNDO TABLESPACE

ORA-30013

SQL> drop tablespace UNDOTBS1 including contents and datafiles;

ERROR at line 1:

ORA-30013: undo tablespace 'UNDOTBS1'is currently in use


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TO FIND ALL UNDO TABLESPACES

SQL> select tablespace_name , status from DBA_TABLESPACES

Where tablespace_name like '%UNDO%';

Only one undo tablespace can be active at a time. Here UNDOTBS1. We cannot

drop an undo tablespace if it is being used by any instance or if it contains any undo

data needed to roll back uncommitted transactions.


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SWITCHING UNDO TABLESPACE

SQL>alter system set undo_tablespace=undo_tsname;

SQL> alter system set undo_tablespace='UNDOTBS';

UNASSIGN CURRENT UNDO TABLESPACE

SQL>alter system set undo_tablespace=' ';

SQL>alter system set undo_tablespace=' '


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DROP UNDO TABLESPACE

SQL> drop tablespace including contens and datfiles;

FIND ALLOCATED/FREE SIZE OF THE UNDO DATAFILE

Now I have removed UNDOTBS1&UNDOTEST, my default undo tablespace

is UNDOTBS. Letsperform small test with UNDOTBS.


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POINTS TO NOTE

Space for undo segments is dynamically allocated, consumed, freed, and

reusedall under the control of Oracle Database, rather than by DBAS so

Oracle takes care undo tablespace.

undo_extent_stat.sql

DATABASE_PROPERTIES

The current settings for the default tablespaces can be viewed using the

DATABASE_PROPERTIES view.

SEGMENT_NAME ( ROLL BACK SEGMENT NAME )
https://www.scribd.com/doc/249018916/Undo-Extent-Stat?secret_password=Cocf0nkL3L3Uc3irlLoPhttps://www.scribd.com/doc/249018916/Undo-Extent-Stat?secret_password=Cocf0nkL3L3Uc3irlLoP


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TO GET TABLESPACE METADATA

SQL> set serveroutput on ;

SQL> declare c clob;

begin

for t in( select tablespace_name from dba_tablespaces)

loop

select dbms_metadata.get_ddl('TABLESPACE', t.tablespace_name) into c

from dual;

dbms_output.put_line(c);

dbms_output.put(';');

end loop;

end;

/

SOME IMPORTANT PARAMS ABOUT TABLESPACES

COLUMNS VALUES

CONTENTS PERMANENT , TEMPORARY , UNDO

STATUS ONLINE , OFFLINE , READ ONLY

EXTENT_MANAGEMENT DICTIONARY , LOCAL

ALLOCATION_TYPE SYSTEM ( autoallocate), UNIFORM (manual )

SEGMENT_SPACE_MANAGEMENT MANUAL , AUTO

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Tablespace mgmt in 10g.pdf