Tablespace mgmt in 10g.pdf

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g ****

INTRODUCTION TO TABLESPACES LOGICAL storage 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. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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 extent allocation in the data dictionary, are called DICTIONARY MANAGED. Tablespaces that record extent allocation in the

tablespace (datafile) header, are called LOCALLY MANAGED. DMT is an obsolete Technology. Always LMT is superior to DMT in every respect.

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MANAGING TABLESPACES IN ORACLE 10g

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 TEST

EXTENT_MANAGEMENT DICTIONARY

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MANAGING TABLESPACES IN ORACLE 10g

ORA - 12913

Let’s check SYS.FET$ view to tablespace TEST (dictionary managed ). SQL> select * from SYS.FET$ where ts#='6'; (test tablespace). TS#

6

FILE#

4

BLOCK#

2

LENGTH

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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MANAGING TABLESPACES IN ORACLE 10g

Let’s 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 40960

MIN_EXTENTS 1

MAX_EXTENTS NEXT_EXTENT PCT_INCREASE 505

40960

50

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MANAGING TABLESPACES IN ORACLE 10g

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 SYSTEM tablespace 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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

As I said , see the keyword "autoallocate" why extents are allocated with different sizes as “autoallocate” specifies extent sizes 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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MANAGING TABLESPACES IN ORACLE 10g

Let’s 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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MANAGING TABLESPACES IN ORACLE 10g

When creating tablespace test , I have mentioned ‘UNIFORM’ so all extents sizes are same. We can see bytes column from following screen shot.

EXAMPLE II ( EXTENTS ALLOCATIONS BY SYSTEM)

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MANAGING TABLESPACES IN ORACLE 10g

When creating tablespace samp , I did NOT mention ‘UNIFORM’ so extents sizes are NOT same. We can see bytes column from following screen shot.

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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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 SIZE bytes (use K or M to specify the extent size).

When the SYSTEM tablespace is dictionary managed other tablespaces can be managed 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). Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

MANAGING TABLESPACE CREATE TABLESPACE SYNTAX - CREATING A NEW TABLESPACE

SQL> create tablespace datafile ‘file path’ size m ; SQL> create tablespace TEST datafile 'test01.ora' size 10m; SQL> create tablespace TEST datafile ‘/u01/oradata/test02.ora’ size 15m; Tablespace created. If path is not specified, by default it is located at dbs directory

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 Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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 'new file path' Database altered SQL> alter database open; Database opened. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

II) SYNTAX SQL>alter database RENAME FILE ‘ old file path’ to 'newfile path’; SQL>alter database rename file ‘/u01/app/test.dbf ’ to ‘/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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MANAGING TABLESPACES IN ORACLE 10g

SYSTEM tablespace should be “ DICTIONARY MANAGED ” otherwise cannot

create dictionary managed tablespaces.

As far as I remember, dbca creates 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 ‘file pathf' size m extent management LOCAL; SQL>create tablespace samp datafile '/u01/app/oracle/oradata/samp/samp01 .dbf' size 20m extent management local; Tablespace created. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g *************

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

SQL> create tablespace datafile ‘filepath’ size m AUTOEXTEND ON MAXSIZE m;

SQL> create tablespace test datafile '/u01/oradata/samp/test03.ora' size 10m autoextend on maxsize 100m; EXAMPLE –III

SQL> create tablespace datafile ‘filepath’ size m 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

SQL> create tablespace datafile ‘filepath’ size m AUTOEXTEND ON MAXSIZE UNLIMITED.

SQL> create tablespace test datafile '/u01/oradata/samp/test04.ora' size 10m autoextend on maxsize 100m; Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

EXAMPLE - V

SQL> create tablespace add datafile ‘filepath’ size m AUTOEXTEND 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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MANAGING TABLESPACES IN ORACLE 10g

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 Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

CHECKING DATAFILE’S BYTES , BLOCKS IN DATABASE

CHECKING DATAFILE’S UNDER ANYONE TABLESPACE

CHECKING DATAFILE FILE_ID , BYTES , FILE_NAME UNDER TABLESPACE

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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

PERMANENT TABLESPACE

Permanaent tablespaces can be either small tablespaces or big 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. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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. Oracle10g introduced 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 “. Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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 temporary type. We can check total_extents , extent_size, total_blocks, free_extents, free_blocks from v$sort_segment view. SQL> select * from V$SORT_SEGMENT; Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

ADDING DATAFILE TO UNDO TABLESPACE

SQL> alter tablespace add ‘file path’ 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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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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MANAGING TABLESPACES IN ORACLE 10g

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. Let’s perform small test with UNDOTBS.

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MANAGING TABLESPACES IN ORACLE 10g

POINTS TO NOTE

Space for undo segments is dynamically allocated, consumed, freed, and reused—all under the control of Oracle Database, rather than by DBA’S

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 )

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu

MANAGING TABLESPACES IN ORACLE 10g

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

Exploring the Oracle DBA Technology by Gunasekaran ,Thiyagu