Oracle 9.2 – New features in the SAP world Jürgen Kirschner (Oracle) Senior Principal Technical...

Oracle 9.2 – New features in the SAP world

Jürgen Kirschner (Oracle)Senior Principal Technical [email protected]

Who we are?

Our group:

• We are working for Oracle’s ”Solution Center SAP Support and Services”• Based at SAP• Responsible for Development Support• offers Advanced Product Services - APS (Workshops, Migration, Onsite Services)• Customers: Dow Corning, Chevron, Shell, Hershey, Bristol-Myers Squibb, SAP, Schindler, Grainger, Black & Decker, Callaway, Wyeth, GPU, ...

Who we are?

Contact person in the US:

Paul Loos

Sr. Principal Support [email protected]: 612.839.5957

Why should I upgrade?

PerformanceStability

Features Nice presentation

Company decision

Why should I upgrade?

Because you have to!8.1.7 will be desupported by the end of 2003. Please check SAP note #578113 and Oracle metalink note #148054.1.

Whether or not there will be an Extended Maintenance Support (EMS) for SAP customers has not yet been decided.

We recommend to start the evaluation process soon.

Please check note #626172.

Features

SAP note#598678 (at the moment released internally only)

Describes the current features officially supported by SAP.

Will be updated continuously during the next months to reflect changes.

The following presentation is covering the features from the Oracle point of view and is only talking about such features where their usage makes sense in an SAP environment

Features (Part I)

• Automatic PGA tuning• Automated undo management (AUM)• Flashback query• Parameter file (spfile)• Online table redefinition• Resumable session

Automated PGA tuning


Oracle 6/7/8Parameters which control memory allocation of EACH shadow process (sort_area_size, hash_area_size, …)

Oracle 9iParameters which control memory allocation of EACH shadow process (sort_area_size, hash_area_size, …)

OR



Idea:

Instead of each shadow process allocating private memory (and keeping it) for temporary operations like sorts, Oracle is providing a kind of ‘shared area’. If this workarea is no longer needed, the memory is freed against the OS and therefore can be used by all other shadow processes.

Note:The memory will not be pre-allocated.


Example: First peak: Sort by session A

Second peak: Sort by session B

Third peak: Sort by session A+B at the same time


How to activate?

Init.ora or spfile:

WORKAREA_SIZE_POLICY = AUTOPGA_AGGREGATE_TARGET = <maximum amount of memory>

Please check OSS note #180605 for SAP’s recommendations for BW systems.


Restrictions (I):

• Each shadow process can by default only allocate up to 5% of the overall pga_aggregate_target value• Parallel operations can allocate up to 30% of the overall pga_aggregate_target value• Each shadow process can by default only allocate up to 200MB of memory. • CKPT process is permanently checking/controlling the utilization and adjusting the memory allocation requests


Restrictions (II):

• If not enough memory is available, space in the temporary tablespace will be allocated (as with the ‘old’ behavior)

Automated Undo Management (AUM)


How long would it take if I now leave the room and request from ALL of you to define a concept for a classic rollback segment layout to which EVERYONE agrees?

Question:

Answer:

Private opinion:

Forever!


With 9i, Oracle has introduced the Automated Undo Management (AUM).

What is new in AUM?

• Oracle controls the number of undo segments (adding new if necessary)

• A special tablespace is introduced for handling only undo segments

• You can decide for how long the undo information SHOULD stay in the undo segments


How to activate?

Init.ora or spfile:

UNDO_MANAGEMENT = AUTOUNDO_TABLESPACE = <tablespace name>

Note: The tablespace must be created BEFORE switching to AUM. The default value for undo_management is ‘MANUAL’ (=classic rollback segment setup)


How to create an undo tablespace?

SQL:Create undo tablespace<name><datafile>;

Note:The TS will be created as a locally managed TS with autoallocate

(OEM screenshot)


Additional information:

• After startup, 10 undo segments are always active

• If more than 10 active concurrent DML operation are present, for every new concurrent DML operation, a new undo segment will be created/activated (automatically)

• You can create multiple undo tablespaces. However only 1 undo tablespace can be active at one time

• The name of the segments are: ‘_SYSSMU<n>$’

• The segment type is: ‘TYPE2 UNDO’


Parameter ‘undo_suppress_errors’

The default value for this parameter is false.

If you set this parameter to true, errors regarding classic rollback segments will not be signaled. Mainly the Oracle error ORA-30019 will be suppressed.

This parameter can help if you have scripts or optimized code for the classic rollback segment setup. Otherwise, after switching to AUM an error would be signaled.


Example (I):

SQL> set transaction use rollback segment prs_1;set transaction use rollback segment prs_1*ERROR at line 1:ORA-30019: Illegal rollback Segment operation in Automatic Undo mode

SQL> alter system set undo_suppress_errors = true scope=memory;System altered.

SQL> set transaction use rollback segment prs_1;Transaction set.


Example (II):

SQL> create rollback segment RBS_NEW;create rollback segment RBS_NEW*ERROR at line 1:ORA-30019: Illegal rollback Segment operation in Automatic Undo mode

SQL> alter session set undo_suppress_errors = true;Session altered.SQL> create rollback segment RBS_NEW;Rollback segment created.

SQL> select * from dba_rollback_segs where segment_name = 'RBS_NEW';no rows selected

ONLY THE ERROR WILL BE SUPPRESSED!!


Parameter ‘undo_retention’ (I)

The default value for this parameter is 900 (value is seconds).

This parameters controls for how long Oracle is TRYING to keep read consistent information within the undo segments.

If you set this to a large value, the number of ORA-1555 errors can be reduced, however, you may will need a lot of space.


Parameter ‘undo_retention’ (II)

If the undo tablespace does not have more free space but we have not yet reached the time specified with undo_retention, no error will be signaled.

We are then reusing existing blocks.

Advice:Create the undo tablespace with the same size as your current PSAPROLL and set undo retention to e.g. 12 hours. Then monitor the usage of undo segments by checking V$rollstat and V$undostat

Flashback query

Flashback query

This is one of the really nice features with 9i. Let us have a look at an example:SQL> select * from flash_new; T1 T2---------- ---------- 1 xsdfsadfSQL> @get_scnThis is the current SCN: 26214082SQL> delete flash_new;1 row deleted.SQL> commit;Commit complete.SQL> select * from flash_new;no rows selectedSQL> create table flash_rescue as select * from flash_new as of scn 26214082;Table created.SQL> select * from flash_rescue; T1 T2---------- ---------- 1 xsdfsadf

Flashback query

Facts about flashback query:• will work with AUM and classic RBS (but flashback query is designed to work with AUM – parameter undo_retention)• prerequisite is, that the data is still in the undo segments (otherwise ORA-1555 will be signaled)• you can use a time based or a scn based approach• for LONG or LONG RAW columns, you have to create a view and then use PL/SQL to get the data.• exp can also be used (FLASHBACK_SCN, FLASHBACK_TIME)

• maximum flashback time is 5 days (if the system is running the whole time – server uptime)

Flashback query

Attention:

If you create a new table, you can not immediately use flashback query.

You have to wait several minutes before you can use this feature.

SPFILE

Spfile

• Binary parameter file managed by the Oracle server• Location: default: $ORACLE_HOME/dbs (Unix) %ORACLE_HOME%/database (NT)• Default name: spfile<SID>.ora• Search path (Unix): $OH/dbs/spfile$ORACLE_SID.ora $OH/dbs/spfile.ora $OH/dbs/init$ORACLE_SID.ora• Search path (NT): same as above; just replace dbs with database

Spfile = Server parameter file

Spfile

• How to activate: SQL> create spfile from pfile;• How to check if a spfile is active: SQL> show parameter spfile• For the creation of a spfile, you need sysdba privileges• If a parameter cannot be changed online, an error will be raised (ORA-02096 )• Advantages:

• no OS login necessary• Changes can be made immediately (in memory) and in the spfile

Spfile

Examples:

- alter system set optimizer_index_cost_adj = 20 scope=spfile; - alter system set max_dump_file_size=unlimited scope=BOTH ;

- alter system set max_dump_file_size=1000 scope=memory;

- alter system reset user_dump_dest scope=spfile sid='*';

- alter system set optimizer_index_cost_adj = 20 comment = 'Changed on July/19/2002 - old: 10 new: 20 reason: advised by JK - Oracle‘ scope = spfile;

- alter system set event = '10191 trace name context forever, level 1', '10181 trace name context forever, level 1' scope=spfile;

Spfile

Advices:• backup your spfile in regular timeframes SQL> create pfile=/../../../ from spfile;• Be careful when you change parameters which can have multiple lines (events)• If you switch to a spfile setup, you should rename your original init<SID>.ora• Get familiar with V$parameter, V$parameter2, V$spparameter V$system_parameter

Note:If you are using the Oracle Upgrade Assistant, a spfile will be created automatically!!!

Online table redefinition


• Online redefinition is based on a PL/SQL package • By default, a table which is planned to be redefined, needs a primary key constraint• Tables which contain LONG or LONG RAW fields can NOT be redefined online• Online table redefinition is based on the materialized view concept• The target table can have a different layout than the source table. This is the reason for the wording ‘redefinition’• You are responsible for the creation of the target table and the correct settings for this table (default values)

“OR” Online table reorganization


Walk through example:

SQL> create table test_redef (t1 number, t2 varchar2(10));Table created.

SQL> alter table test_redef add constraint pk_test_redef primary key (t1);Table altered.

SQL> begin for i in 1..10000 loop insert into test_redef values (i,'XXX'); end loop; end; /PL/SQL procedure successfully completed.

SQL> create table test_redef_new as select * from test_redef where rownum < 1;Table created.

SQL> exec dbms_redefinition.can_redef_table('SAPR3','TEST_REDEF');PL/SQL procedure successfully completed.

SQL> exec dbms_redefinition.start_redef_table('SAPR3','TEST_REDEF','TEST_REDEF_NEW');PL/SQL procedure successfully completed.


SQL> select count(*) from test_redef;

COUNT(*) ---------- 10000

SQL> select count(*) from test_redef_new;

COUNT(*) ---------- 10000

SQL> begin for i in 10001.. 50000 loop insert into test_redef values (i,'XXX'); end loop; end; /PL/SQL procedure successfully completed.

SQL> commit;Commit complete.


SQL> select count(*) from test_redef;COUNT(*) ---------- 50000

SQL> select count(*) from test_redef_new; COUNT(*) ---------- 10000

SQL> exec dbms_redefinition.sync_interim_table('SAPR3','TEST_REDEF','TEST_REDEF_NEW');PL/SQL procedure successfully completed.

SQL> select count(*) from test_redef_new; COUNT(*) ---------- 50000

SQL> begin for i in 50001.. 60000 loop insert into test_redef values (i,'XXX'); end loop; end; /PL/SQL procedure successfully completed.


SQL> commit;Commit complete.

SQL> comment on table test_redef is 'This is the original table';Comment created.

SQL> comment on table test_redef_new is 'This is the new table';Comment created.

SQL> select count(*) from test_redef_new;COUNT(*) ---------- 50000

SQL> select count(*) from test_redef;COUNT(*) ---------- 60000


SQL> alter table test_redef_new add constraint 2 pk_test_redef_new primary key (t1);Table altered.

SQL> create index i_test_redef_new on test_redef_new (t2);Index created.

SQL> analyze table test_redef_new compute statistics;Table analyzed.

SQL> exec dbms_redefinition.finish_redef_table('SAPR3','TEST_REDEF','TEST_REDEF_NEW');PL/SQL procedure successfully completed.


SQL> select table_name, substr(comments,1,29) from dba_tab_comments 2 where table_name like 'TEST_REDEF%';

TABLE_NAME SUBSTR(COMMENTS,1,29)------------------------------ -----------------------------TEST_REDEF This is the new tableTEST_REDEF_NEW This is the original table

Tables are automatically renamed

SQL> select table_name, index_name from dba_indexes 2 where table_name like 'TEST_REDEF%‘ 3 order by table_name;

TABLE_NAME INDEX_NAME------------------------------ ------------------------------TEST_REDEF PK_TEST_REDEF_NEWTEST_REDEF I_TEST_REDEF_NEWTEST_REDEF_NEW PK_TEST_REDEF


• Based on a step by step implementation, the DBA always has full control over the procedure• Based on the materialized view implementation, this is not a completely new concept• You can perform ALL tasks on the ‘shadow’ table before performing the final switch (statistics, index creation)• If you decide to terminate the reorg, you simply execute: exec dbms_redefinition.abort_redef_table ('SAPR3',‘orig_tab ,‘new_tab');

• The original table will not be dropped automatically after the switch

Summary:

Resumable session

Resumable session

SQL> create tablespace test datafile 'D:\ORACLE\ORADATA\V92\test.dbf' size 5M;Tablespace created.

SQL> create table test_resumable (t1 number) 2 tablespace test storage (initial 10M);create table test_resumable (t1 number)*ERROR at line 1:ORA-01659: unable to allocate MINEXTENTS beyond 4 in tablespace TEST

Example:

Resumable session

SQL> alter session enable resumable;Session altered.

SQL> create table test_resumable (t1 number) 2 tablespace test storage (initial 10M);

The session is waiting!

V$session_wait will show us:“statement suspended, wait error to be cleared”

Resumable session

In the alert file we will find:

Thu Apr 17 09:43:52 2003statement in resumable session 'User SAPR3(62), Session 13, Instance 1' was suspended due to ORA-01659: unable to allocate MINEXTENTS beyond 4 in tablespace TEST

In the view dba_resumable will find additional information about this suspended statement!

Resumable session

• ‘alter session resumable’ is setting statements, which are running into SPACE errors, ‘on hold’• Errors which are covered are (for example): ORA-1536, ORA-1653, ORA-1659, ORA-30036• The suspend time is by default 7200 seconds• The suspend time can be also set: SQL> alter session enable resumable timeout 10; • To activate for all sessions, a logon trigger is necessary• You can also setup an ‘AFTER SUSPEND’ trigger on database level, where you can define actions depending on the kind of error

Summary:

Resumable session

‘alter session resumable’ does NOT work in combination with database links:

SQL> create database link to_my_own_database 2 connect to sapr3 identified by sap using 'V92';Database link created.

SQL> alter session enable resumable;Session altered.

SQL> select * from dual@to_my_own_database;select * from dual@to_my_own_database *ERROR at line 1:ORA-30044: Resumable cannot be enabled with distributed transactions

Attention:

Features (Part II)

Features (Part II)

• Alter system suspend holds all I/O

• Dynamic SGA dynamic increasing/decreasing of different areas of the SGA

• CBO• Index skip scan• Dynamic sampling• New first_rows hint CBO• Parameter changes• Bind variable peeking

Features (Part II)

• Different Oracle block sizes for tablespaces • Automated Space Management also called Bitmap Managed Blocks (BMB) new method of block dispatching for insert operations and handling of re-usage of blocks (pctused will not work anymore)

• Two pass recovery• Merge statement (upsert) combination of insert/update for synchronization of two tables

• RAC (Real Application Cluster)• Compress for tables• …

Summary

9.2 offers a lot of helpful and good features for the daily work of a DBA.

There is a lot for you to learn!

Information

At 12:30 PM, there will be a Round Table Lunch – “Oracle SIG”

If you have time, you are welcome to join. We will meet after this presentation at the Oracle booth at the vendor fair.

Thank you for attending!

Please remember to complete and return your evaluation form following this session.

Session Code: [902A]

Oracle 9.2 – New features in the SAP world Jürgen Kirschner (Oracle) Senior Principal Technical...

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