PCTFREE and PCTUSED

hai !!!
I want to improve insertion and retriving performance of a table !'
* Could i achieve this by changing PCTFREE and PCTUSED values ?
* If so, what values do i need to put ?
- my table contains lakhs of records.
- involves continuos insertion of records.
- Updation is a rare.
- iam using Oracle 10g, data_block_size=8kb, OS : windows-7
* What about change in block size ?
- Do i need to increase it ? or decrease it ?

Not required to specify it if Segment Space Management is AUTO.
Specifying Segment Space Management in Locally Managed Tablespaces
When you create a locally managed tablespace using the CREATE TABLESPACE statement, the SEGMENT SPACE MANAGEMENT clause lets you specify how free and used space within a segment is to be managed. You can choose either manual or automatic segment-space management.
MANUAL: Manual segment-space management uses free lists to manage free space within segments. Free lists are lists of data blocks that have space available for inserting rows. With this form of segment-space management, you must specify and tune the PCTUSED, FREELISTS, and FREELIST GROUPS storage parameters for schema objects created in the tablespace. MANUAL is the default.
AUTO: Automatic segment-space management uses bitmaps to manage the free space within segments. The bitmap describes the status of each data block within a segment with respect to the amount of space in the block available for inserting rows. As more or less space becomes available in a data block, its new state is reflected in the bitmap. These bitmaps allow the database to manage free space automatically.
You can specify automatic segment-space management only for permanent, locally managed tablespaces. Automatic segment-space management is a simpler and more efficient way of managing space within a segment. It completely eliminates any need to specify and tune the PCTUSED, FREELISTS, and FREELIST GROUPS storage parameters for schema objects created in the tablespace. If you specify these attributes, the database ignores them.
can i set PCTFREE and PCTUSED in LMT
http://docs.oracle.com/cd/B12037_01/server.101/b10739/tspaces.htm
Thanks
Kuljeet Pal Singh

Similar Messages

How to find block free space and PCTUSED FOR THE TABLE

HI all,
Due to performance issues for my database , my management ask me to reset the PCTUSED and PCTFREE values , and my doubt is
1)How to find the current PCTUSED and PCTFREE values.
2)How to find block free space and PCTUSED FOR THE TABLE.
Please help me out regarding this.
Regards,
Vamsi.

1)version is 10.2.0.4
2)output of query
tablespace extent_management allocation_type segment_space_management
SYSTEM     LOCAL     SYSTEM     MANUAL
UNDOTBS1     LOCAL     SYSTEM     MANUAL
SYSAUX     LOCAL     SYSTEM     AUTO
TEMP     LOCAL     UNIFORM     MANUAL
USERS     LOCAL     SYSTEM     AUTO
UNDOTBS2     LOCAL     SYSTEM     MANUAL
INS     LOCAL     SYSTEM     AUTO
CONFTBS     LOCAL     SYSTEM     AUTO
REINS     LOCAL     SYSTEM     AUTO
ANALYST     LOCAL     SYSTEM     AUTO
BI     LOCAL     SYSTEM     AUTO
INTRFC     LOCAL     SYSTEM     AUTO
COGNOS     LOCAL     SYSTEM     AUTO
TS_INDX     LOCAL     SYSTEM     AUTO
TS_CHOLAWEB     LOCAL     SYSTEM     AUTO
TS_DASBOARD     LOCAL     SYSTEM     AUTO

(PCTFREE, PCTUSED) and Storage parameters

HI,
I am confused about (PCTFREE, PCTUSED) and Storage parameters(initial, next, pctincrease etc.)
As far as i have read PCTFREE and PCTUSED are used to control free and used space in a datablock and also these parameters related to Manual segment space management in Locally managed tablespace(i.e we need to manually set and tune these parameters). Whether these parameter are used in Dictionary managed tablespace or not?
Also, Storage parameters(intital, next, PCTUSED etc) are used in Dictionary managed tablespace. But in locally managed tablespaces how they are set as i have read we need not set these in locally managed tablespaces.
So, can you explain me about differences of these parameters with regard to Locally and Dictionary managed tablespaces in Oracle 9i and 10g platform on RHEL.

Hi,
Locally Managed Tablespace :-
A tablespace that can manage extent allocation by itself is called locally managed tablespace.
Using the bitmap in each datafile to keep track of the freed or used status of blocks in that datafile.
Each bit in the bitmap corresponds to a block or a group of blocks.
When an extent is allocated or freed for reuse, Oracle changes the bitmap values to show the new status of the blocks.
These changes do not generate rollback information because they do not update tables in the data dictionary.
Now remember, storage parameters
NEXT,
PCTINCREASE,
MINEXTENTS,
MAXEXTENTS, and
DEFAULT STORAGE are not valid for extents that are managed locally
Extents allocated in LMT :-
LMT have extent sizes either UNIFORM or variable extent sizes
For UNIFORM extents you can specify an extent size. The default size is 1MB.
and for AUTOALLOCATE extents you can specify the size of the initial extent and Oracle determines the optimal size of the additional extents, with a minimum extent size of 64KB
Example :-
Extent of uniform size
CREATE TABLESPACE test
DATAFILE 'tet.dbf'
EXTENT MANAGEMENT LOCAL
UNIFORM SIZE 256K;
Specifying Segment Space Management in Locally Managed Tablespaces
When you create a locally managed tablespace using the CREATE TABLESPACE statement, the SEGMENT SPACE MANAGEMENT clause allows you to specify how free and used space within a segment is to be managed.
MANUAL (MSSM) :- refers to oracle use free lists for managing free space within segments
because of the need to specify and tune the PCTUSED, FREELISTS, and FREELISTS GROUPS storage parameters for schema objects created in the tablespace
AUTO :-
Oracle use bitmaps to manage the free space within segments- automatic segment-space management
(ASSM)
Example :-
CREATE TABLESPACE lmtbsb DATAFILE '/u02/oracle/data/lmtbsb01.dbf' SIZE 50M
EXTENT MANAGEMENT LOCAL - LMT
SEGMENT SPACE MANAGEMENT AUTO; - ASSM
- DMT :-
Example :-
CREATE TABLESPACE tbsb
DATAFILE '/u02/oracle/data/tbsa01.dbf' SIZE 50M
EXTENT MANAGEMENT DICTIONARY -- specified how to manag the extent in DB
DEFAULT STORAGE (
INITIAL 50K
NEXT 50K
MINEXTENTS 2
MAXEXTENTS 50
PCTINCREASE 0); -- you have specified how extents in memory should increase
In the above example you have created dmt and specified the storage parameter for Extents, that is
how they much allocated as data get inserted in to the segments(tables) .
refer : http://www.mpi-inf.mpg.de/departments/d5/teaching/ss05/is05/oracle/server.920/a96521/tspaces.htm#636
- Pavan Kumar N
Oracle 9i/10g - OCP
http://oracleinternals.blogspot.com/

PCTUsed - PCTFree

Hi,
I am using the below mentioned storage parameters for my tables, due to which oracle isn't able to use the free space after a delete. I can alter the value of PCTUSED but is there a way to remove the PCTUSED parameter from the table defination and let oracle manage it using alter table command so that i dont have to create the table again?
PCTFREE 10
PCTUSED 40
STORAGE(MINEXTENTS 1
MAXEXTENTS 1024
PCTINCREASE 0
BUFFER_POOL DEFAULT
Thanks
Rajat Thakran

exactly ASSM ignores pctfree and pctused while is MSSM it consider which is bydefault 10 and 40 percent respectively.Come what may if you just define pctfree and let the oracle use its own pctused it would be default 40 percent.
SQL> conn sys/sys as sysdba
Connected.
SQL> create tablespace myspace
2   datafile 'c:\myfile.dbf' size 1G
3 extent management local uniform size 100M
4 /
Tablespace created.
SQL> conn scott/tiger
Connected.
SQL> drop table t
2 /
Table dropped.
SQL> create table t (a number) tablespace myspace
2 /
Table created.
SQL> conn sys/sys as sysdba
Connected.
SQL> select tablespace_name,status,contents,extent_management,segment_space_management
2    from user_tablespaces
3 /
TABLESPACE_NAME                STATUS    CONTENTS EXTENT_MAN SEGMEN
SYSTEM                         ONLINE    PERMANENT LOCAL      MANUAL
UNDOTBS1                       ONLINE    UNDO      LOCAL      MANUAL
SYSAUX                         ONLINE    PERMANENT LOCAL      AUTO
TEMP                           ONLINE    TEMPORARY LOCAL      MANUAL
USERS                          ONLINE    PERMANENT LOCAL      AUTO
MYSPACE                        ONLINE    PERMANENT LOCAL      MANUAL
6 rows selected.
SQL> select pct_free,pct_used
2     from user_tables
3    where table_name='T'
4   /
PCT_FREE   PCT_USED
        10         40
SQL> conn scott/tiger
Connected.
SQL> create table t1 (a number) pctfree 20 tablespace myspace
2 /
Table created.
SQL> select pct_free,pct_used
2    from user_tables
3   where table_name='T1'
4 /
PCT_FREE   PCT_USED
        20         40
SQL> how you are identifying that oralce is not reusing that block which cross pctused defined percentage?
Khurram

Storage Parameter - PCTFREE & PCTUSED

My question is regarding storage parameter PCTFREE and PCTUSED. I have little bit confusion to determine PCTUSED calculation.
Suppose we set PCTFREE 20% and PCTUSED 50%. Initially, a block is empty, an INSERT fill free space 30% and after this UPDATE fill 20% reserved PCTFREE space.
My question is, the block will be available for new INSERT.
Thank

asif.maqbool wrote:
Thanks Aman for sending links. I read and understood. But I'd like to know the block availability. Do we consider filled PCTFREE space to calculate PCTUSED space?Are you sure that you read the link?
The block's availability is based on the PCTUSED marker (only in the Manual Segment Space Management). PCTFREE is going to be a reserved space for the subsequent updates.
This diagram should clear the concept.
http://docs.oracle.com/cd/E11882_01/server.112/e25789/logical.htm#BABHHIDA
My understanding is PCTUSED percentage only for new insert and the block is available until PCTUSED to reach specified percentage doesn't matter PCTFREE filled or not. A PCTFREE percentage is a separate space allocation in the block that we do not consider for PCTUSED space. If we set 20% PCTFREE and 50% PCTUSED so, we will use the over all 70% of a block space 20% for UPDATE and 50% for new INSERT.Wrong! Please read and re-read the given links.
I'd appreciate if you or anyone to correct my concept if there is something wrong.Though its not going to be of much use right now as you are not clear with the basic concepts , this link should help in knowing the idea behind calculation required to set the parameters(only for MSSM) ,
http://asktom.oracle.com/pls/asktom/f?p=100:11:::::P11_QUESTION_ID:733825532206
Aman....

Plz guide me on the formula of PCTUSED

Hi
I read in a blog to find out blocks available for insert are
Blocks with total filled volume < (BLOCKSIZE – overhead – (blocksize*(1-(PCTFREE/100)))
In the above formula I am unable to understand the meaning of
blocksize*(1-(PCTFREE/100))
Please explain.
Thanks

The documentation nicely explains PCTFREE and PCTUSED.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/logical.htm#sthref344
The author performs some calculations to conceptually show how to understand if a block is available for inserts or not.

Specifying segments and block size manaually

Hi, just a quick question,
But could anyone help me understand why someone may manually add segments to a table space (or is it a data file they would be added to) ? does auto extend not take care of this?
And secondly ... why would you increase or decrease the block size of a segment?... is this because you may have small or large sized rows within a table and want a block size to acompany this?
Any help would be appriciated

Hi,
In Oracle free space can be managed automatically or manually,You specify automatic segment-space management when you create a locally managed tablespace
Free space can be managed automatically inside database segments. The in-segment free/used space is tracked using bitmaps, as opposed to free lists. Automatic segment-space management offers the following benefits:
-Ease of use
-Better space utilization, especially for the objects with highly varying size rows
-Better run-time adjustment to variations in concurrent access
-Better multi-instance behavior in terms of performance/space utilization
For manually managed tablespaces, two space management parameters, PCTFREE and PCTUSED, enable you to control the use of free space for inserts and updates to the rows in all the data blocks of a particular segment. Specify these parameters when you create or alter a table or cluster (which has its own data segment). You can also specify the storage parameter PCTFREE when creating or altering an index (which has its own index segment).
see this link
http://download.oracle.com/docs/cd/B10500_01/server.920/a96524/b_deprec.htm#634923 :)

Why fragmentation in T1 is huge and in T2 is zero

Hi
I have a busy DB 8107 , with compatible 8.0.5.0.0 on Windows 2000 SP4
(i am going to 11g very soon)
i have 2 tables , t1 in tablespace1 and t2 in tablespace2
both T1 and T2 are getting lots of inserts and deletes ,there are huge fragmentation in T1 but not T2
tablespace1 and tablspace2 are identical in definition
EX:
CREATE TABLESPACE tablespace1 DATAFILE
LOGGING
DEFAULT STORAGE (
INITIAL 104K
NEXT 104K
MINEXTENTS 1
MAXEXTENTS UNLIMITED
PCTINCREASE 0
ONLINE
PERMANENT
EXTENT MANAGEMENT DICTIONARY;
Giving no maintenance has been done to T1 or T2 or their 2 tablespaces in the last 24 months
My question is why there are huge fragmentation in t1 but not t2?
Thanks
Edited by: user8803475 on Aug 21, 2012 11:14 PM

Think about how the rows are being inserted and deleted.
In general, there are two extremes in the way that data is inserted and removed from a table.
The first way is usually chronological and sees the data getting inserted into the table, sitting there for a while then getting deleted.
In this scenario, rows have a consistent lifespan and the datablocks will in general, get filled then get emptied.
Think of a log table that is retained for 1 year. The rows get inserted and deleted using the same time based criteria.
These data blocks will get filled, get emptied and get reused pretty regularly.
Fragmentation will be near zero.
The second way is more random. The rows get inserted and deleted on entirely different criteria.
Think of a table in which rows get inserted based on time, but get deleted based on some other value in the data.
These data blocks will be filled with inserts, but partially emptied with the deletes.
The database will reuse the space when it falls below a threshold but will otherwise be "fragmented"
This explains the "why did it get this way"
Now, the part about should you "fix" it gets more to the point.
Is the "fragmentation" a problem? probably not.
Disk space is pretty cheap and your time is not.
You say that this is a pretty busy database. Unless your fragmented table has been configured with a bad PCTFREE and PCTUSED setting, the database will reuse the space.
Is it worth your time to tweak the use/reuse of small amounts of disk space?
An Oracle database does not require special maintenance procedures to reuse disk space.
The management of this space is explained very well in the database concepts guide:
http://docs.oracle.com/cd/E11882_01/server.112/e25789/logical.htm#i13690

Pctused is confusing

my database objects have pctused =40 and pctfree=10.huge insertiton and deletions occure because of pctused =40 space is not reused.by alter table ....pctused=90 but still prior to this statemnt space are not reused.Then i took the backup of the table and recreated it with pctused=90 and the space was being reused .
why alter table <tab_name> pctused 90 is not allowing to reuse the previous space .

A smaller PCTUSED has the following effects:
1. Reduces processing costs incurred during UPDATE and DELETE statements for moving a block to the free list when it has fallen below that percentage of usage
2. Increases the unused space in a database
A larger PCTUSED has the following effects:
1. Improves space efficiency
2. Increases processing cost during INSERT and UPDATE
===========================================================
The sum of PCTFREE and PCTUSED must be equal to or less than 100
The smaller the difference between 100 and the sum of PCTFREE and PCTUSED (as in PCTUSED of 75, PCTFREE of 20), the more efficient space usage is, at some performance cost
==========================================================
As you dont have much updation on the tables keep the PCTFREE low so that 1.Allows inserts to fill the block more completely
2.more rows or entries for each block
Regards,
Sandeep P.

Multiple record insert problem in Oracle Procedure that uses a cursor

Dear X-pert guies,
I have a oracle procedure that use a cursor, I repeatedly make query on 1st table using cursor value and insert that queried value(of 1st table) to 2nd table
y_summary. y_summary has composite primary key :PK_Y_SUM (BILL_DATE, TRUNK_MGR, IDD_FLAG, PK_FLAG, PREFIX).*
when i run the procedure explicit2('201001'); the it gives me the error:::: begin explicit2('201001'); end;_
ORA-00001: unique constraint (PRM.PK_Y_SUM) violated_
ORA-06512: at "PRM.EXPLICIT2", line 413_
ORA-06512: at line 1_
but when i remove the composite primary key from y_summary table then, the procedure runs ok and make so many duplicate entries in y_summary.
but i want the single record to be inserted for single time in y_summary ,so You guies are honorly requested to make the required help .
the structure of y_summary Table and Procdure code is given below.
Table:
-- Create table
create table Y_SUMMARY
BILL_DATE VARCHAR2(10) not null,
TRUNK_MGR VARCHAR2(20) not null,
IDD_FLAG VARCHAR2(10) not null,
PK_FLAG NUMBER(2) not null,
OUTCALLS NUMBER(20,2),
OUTDUR NUMBER(20,2),
PREFIX VARCHAR2(10) not null
tablespace TBS_PRM_D01
pctfree 10
pctused 40
initrans 1
maxtrans 255
storage
initial 64K
minextents 1
maxextents unlimited
-- Create/Recreate primary, unique and foreign key constraints
alter table Y_SUMMARY
add constraint PK_Y_SUM primary key (BILL_DATE, TRUNK_MGR, IDD_FLAG, PK_FLAG, PREFIX)
using index
tablespace TBS_PRM_D01
pctfree 10
initrans 2
maxtrans 255
storage
initial 64K
minextents 1
maxextents unlimited
Procedure:
create or replace procedure explicit2( month_val in varchar2) is
cursor explicit_cur is select dest_code from y_table where dest_code like '44%' order by dest_code desc;
dummy varchar2(100);
lv_length Number(9);
sqlstr varchar2(2500);
rec_count1 number;
rec_count2 number;
rec_count3 number;
begin
open explicit_cur;
LOOP
fetch explicit_cur into dummy;
EXIT WHEN explicit_cur%NOTFOUND;
rec_count1 :=0;
rec_count2 :=0;
rec_count3 :=0;
lv_length := length(dummy);
sqlstr := 'select count(*) from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr into rec_count1;
sqlstr := 'select count(*) from y_table_data1 t where t.fee_dur_1_2 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'',
''ITAX1B'',''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr into rec_count2;
sqlstr := 'select count(*) from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'',
''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''012'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr into rec_count3;
if(rec_count1>0) then
sqlstr := 'insert into y_summary(BILL_DATE ,PREFIX, TRUNK_MGR,OUTCALLS , OUTDUR , IDD_FLAG , PK_FLAG )
select '|| month_val||' ,substr(t.orig_called_num,1,'||lv_length||'),t.trunkout_operator ,count(*) , round(sum(ceil(t.duration / 15) * 15) / 60, 0),''00'',''1'' from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||''''|| ' group by t.trunkout_operator,substr(t.orig_called_num,1,'||lv_length||')';
execute immediate sqlstr;
commit;
sqlstr :='DELETE from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr;
commit;
end if ;
if(rec_count2>0) then
sqlstr :='insert into y_summary(BILL_DATE ,PREFIX, TRUNK_MGR,OUTCALLS , OUTDUR , IDD_FLAG , PK_FLAG )
select '|| month_val||' ,substr(t.orig_called_num,1,'||lv_length||'),t.trunkout_operator ,count(*) , round(sum(ceil(t.duration / 15) * 15) / 60, 0),''00'',''0'' from y_table_data1 t where t.fee_dur_1_2 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' group by t.trunkout_operator,substr(t.orig_called_num,1,'||lv_length||')';
execute immediate sqlstr;
commit;
sqlstr :='DELETE from y_table_data1 t where t.fee_dur_1_2 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''00'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr;
commit;
end if;
if(rec_count3>0) then
sqlstr :='insert into y_summary(BILL_DATE ,PREFIX, TRUNK_MGR,OUTCALLS , OUTDUR , IDD_FLAG , PK_FLAG )
select '|| month_val||',substr(t.orig_called_num,1,'||lv_length||'),t.trunkout_operator ,count(*) , round(sum(ceil(t.duration / 15) * 15) / 60, 0),''012'',''0'' from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''012'' group by t.trunkout_operator,substr(t.orig_called_num,1,'||lv_length||')';
execute immediate sqlstr;
commit;
sqlstr :='DELETE from y_table_data1 t where t.fee_dur_1_1 <> 0
and t.out_trunk in (''MHISRM'', ''GEISRM'', ''GEIMRP'', ''MHIMRP'', ''13'', ''ITAX1B'', ''ITAX3B'',''ITAX5B'', ''ITAX6B'', ''ITAX7B'', ''BTIMRP'', ''BTI5RP'', ''BTI6RP'', ''BTI7RP'')
and t.service_code = ''012'' and substr(t.orig_called_num,1,'||lv_length||')='||''''||dummy||'''';
execute immediate sqlstr;
commit;
end if;
end loop;
close explicit_cur;
end explicit2;
Edited by: user10951541 on 25.4.2010 12.08

Dear concern
Really sorry not to make format listing because i am amature to this blog.
my anwser to your way .
1. I have Tested my SQL statements manually in SQL*Plus. this runs ok
2. "Cursor loops, such as the one you have coded here, have been obsolete in Oracle since version 8i 12+ years ago.
Look up BULK COLLECT and FORALL in the docs and use them instead."
I am trying to make use of the BULK COLLECT and FORALL statement in proper location.
3. "Your procedure never performs a commit so no work actually takes place" i need to get the anwser why........................?
4. "On what basis was the decision made to use the default PCTFREE and PCTUSED values of 10 and 40?"
is there any problem if default is used..? if any suggestion........pls
5." You did not format your listing using the CODE tags as explained in the FAQ making your listing unreadable ... so I've not read it.
Please read the FAQ and use the proper way to post code so we can understand it. Then perhaps we can help you further. " really sorry not to make understandable to you..? but i will try from next post..
I really will try to be synced..
My aim is to make query to Table A using the cursor value like( '4422','442','4411','441','44') and get some data in accordance of these values.Then i put the data into another Table B. same time i need to delete the record from Table A containing the prefix value in accordance for example- i compute value for '4422' from Table A and put the computed value to Table B .Then i delete the record from Table A where prefix is '4422' .so that computed value for the next prefix '442' should contain the computed value for 442[0-1] and 442[3-9] .Same way it will be happened for ('4411','441','44'....bla...bla).
Thanks in advance..

Oracle Table Storage Parameters - a nice reading

bold Gony's reading excercise for 07/09/2009 bold -
The below is from the web source http://www.praetoriate.com/t_%20tuning_storage_parameters.htm. Very good material.The notes refers to figures and diagrams which cannot be seen below. But the text below is ver useful.
Let’s begin this chapter by introducing the relationship between object storage parameters and performance. Poor object performance within Oracle is experienced in several areas:
Slow inserts Insert operations run slowly and have excessive I/O. This happens when blocks on the freelist only have room for a few rows before Oracle is forced to grab another free block.
Slow selects Select statements have excessive I/O because of chained rows. This occurs when rows “chain” and fragment onto several data blocks, causing additional I/O to fetch the blocks.
Slow updates Update statements run very slowly with double the amount of I/O. This happens when update operations expand a VARCHAR or BLOB column and Oracle is forced to chain the row contents onto additional data blocks.
Slow deletes Large delete statements can run slowly and cause segment header contention. This happens when rows are deleted and Oracle must relink the data block onto the freelist for the table.
As we see, the storage parameters for Oracle tables and indexes can have an important effect on the performance of the database. Let’s begin our discussion of object tuning by reviewing the common storage parameters that affect Oracle performance.
The pctfree Storage Parameter
The purpose of pctfree is to tell Oracle when to remove a block from the object’s freelist. Since the Oracle default is pctfree=10, blocks remain on the freelist while they are less than 90 percent full. As shown in Figure 10-5, once an insert makes the block grow beyond 90 percent full, it is removed from the freelist, leaving 10 percent of the block for row expansion. Furthermore, the data block will remain off the freelist even after the space drops below 90 percent. Only after subsequent delete operations cause the space to fall below the pctused threshold of 40 percent will Oracle put the block back onto the freelist.
Figure 10-83: The pctfree threshold
The pctused Storage Parameter
The pctused parameter tells Oracle when to add a previously full block onto the freelist. As rows are deleted from a table, the database blocks become eligible to accept new rows. This happens when the amount of space in a database block falls below pctused, and a freelist relink operation is triggered, as shown in Figure 10-6.
Figure 10-84: The pctused threshold
For example, with pctused=60, all database blocks that have less than 60 percent will be on the freelist, as well as other blocks that dropped below pctused and have not yet grown to pctfree. Once a block deletes a row and becomes less than 60 percent full, the block goes back on the freelist. When rows are deleted, data blocks become available when a block’s free space drops below the value of pctused for the table, and Oracle relinks the data block onto the freelist chain. As the table has rows inserted into it, it will grow until the space on the block exceeds the threshold pctfree, at which time the block is unlinked from the freelist.
The freelists Storage Parameter
The freelists parameter tells Oracle how many segment header blocks to create for a table or index. Multiple freelists are used to prevent segment header contention when several tasks compete to INSERT, UPDATE, or DELETE from the table. The freelists parameter should be set to the maximum number of concurrent update operations.
Prior to Oracle8i, you must reorganize the table to change the freelists storage parameter. In Oracle8i, you can dynamically add freelists to any table or index with the alter table command. In Oracle8i, adding a freelist reserves a new block in the table to hold the control structures. To use this feature, you must set the compatible parameter to 8.1.6 or greater.
The freelist groups Storage Parameter for OPS
The freelist groups parameter is used in Oracle Parallel Server (Real Application Clusters). When multiple instances access a table, separate freelist groups are allocated in the segment header. The freelist groups parameter should be set the number of instances that access the table. For details on segment internals with multiple freelist groups, see Chapter 13.
NOTE: The variables are called pctfree and pctused in the create table and alter table syntax, but they are called PCT_FREE and PCT_USED in the dba_tables view in the Oracle dictionary. The programmer responsible for this mix-up was promoted to senior vice president in recognition of his contribution to the complexity of the Oracle software.
Summary of Storage Parameter Rules
The following rules govern the settings for the storage parameters freelists, freelist groups, pctfree, and pctused. As you know, the value of pctused and pctfree can easily be changed at any time with the alter table command, and the observant DBA should be able to develop a methodology for deciding the optimal settings for these parameters. For now, accept these rules, and we will be discussing them in detail later in this chapter.
There is a direct trade-off between effective space utilization and high performance, and the table storage parameters control this trade-off:
For efficient space reuse A high value for pctused will effectively reuse space on data blocks, but at the expense of additional I/O. A high pctused means that relatively full blocks are placed on the freelist. Hence, these blocks will be able to accept only a few rows before becoming full again, leading to more I/O.
For high performance A low value for pctused means that Oracle will not place a data block onto the freelist until it is nearly empty. The block will be able to accept many rows until it becomes full, thereby reducing I/O at insert time. Remember that it is always faster for Oracle to extend into new blocks than to reuse existing blocks. It takes fewer resources for Oracle to extend a table than to manage freelists.
While we will go into the justification for these rules later in this chapter, let’s review the general guidelines for setting of object storage parameters:
Always set pctused to allow enough room to accept a new row. We never want to have a free block that does not have enough room to accept a row. If we do, this will cause a slowdown since Oracle will attempt to read five “dead” free blocks before extending the table to get an empty block.
The presence of chained rows in a table means that pctfree is too low or that db_block_size is too small. In most cases within Oracle, RAW and LONG RAW columns make huge rows that exceed the maximum block size for Oracle, making chained rows unavoidable.
If a table has simultaneous insert SQL processes, it needs to have simultaneous delete processes. Running a single purge job will place all of the free blocks on only one freelist, and none of the other freelists will contain any free blocks from the purge.
The freelist parameter should be set to the high-water mark of updates to a table. For example, if the customer table has up to 20 end users performing insert operations at any time, the customer table should have freelists=20.
The freelist groups parameter should be set the number of Real Application Clusters instances (Oracle Parallel Server in Oracle8i) that access the table.

sb92075 wrote:
goni ,
Please let go of 20th century & join the rest or the world in the 21st century.
Information presented is obsoleted & can be ignored when using ASSM & ASSM is default with V10 & V11I said the same over here for the exactly same thread, not sure what the heck OP is upto?
Oracle Table Storage Parameters - a nice reading
regards
Aman....

Oracle Performance tunning genral question

Hi,
Below is the list of Areas of Oracle db for which tunning activities are done. You are invited to comment to it weather this is complete list or need some addition or deletion. As I'm learning PT for Oracle now a days, therefore I want to expand my knowledge by sharing what I'm learning and what I need to learn.
So comment with Open hearts on it. Espically from experts and Gurus.
Here is the List
1-Planning for Performance, include Storage consideration( Weather it is SAN, NAS, DAS), Network planning and host OS planning with proper configuration for running Oracle.
2-Database desining (Not under-Normalized and not Over-Normalized with proper usage of Indexes, views and Stored Procedures)
3- Instance tunning (Memory structure + B.g Processes)
4- Session tunning.
5- Segment Space tunning.
6- SQL tunning.
This is what uptill what I've learned. If it needs addition kindly tell me what are these. Please also provide me links(good and precise one) for PT tutorials on web.Also note that I'm discussing this w.r.t Single instance non-rac db.
Looking for Good sugessions
Regards,
Abbasi

Hello,
This is the oracle course contents:
Contents
Preface
1 Introduction
Course Objectives 1-2
Organization 1-3
Agenda 1-4
What Is Not Included 1-6
Who Tunes? 1-7
What Does the DBA Tune? 1-8
How to Tune 1-10
Tuning Methodology 1-11
Effective Tuning Goals 1-13
General Tuning Session 1-15
Summary 1-17
2 Basic Tuning Tools
Objectives 2-2
Performance Tuning Diagnostics 2-3
Performance Tuning Tools 2-4
Tuning Objectives 2-5
Top Wait Events 2-6
DB Time 2-7
CPU and Wait Time Tuning Dimensions 2-8
Time Model: Overview 2-9
Time Model Statistics Hierarchy 2-10
Time Model Example 2-12
Dynamic Performance Views 2-13
Dynamic Performance Views: Usage Examples 2-14
Dynamic Performance Views: Considerations 2-15
Statistic Levels 2-16
Statistics and Wait Events 2-18
System Statistic Classes 2-19
Displaying Statistics 2-20
Displaying SGA Statistics 2-22
Wait Events 2-23
Using the V$EVENT_NAME View 2-24
Wait Classes 2-25
Displaying Wait Event Statistics 2-26
Oracle Internal & Oracle Academy Use Only
iv
Commonly Observed Wait Events 2-28
Using the V$SESSION_WAIT View 2-29
Precision of System Statistics 2-31
Using Features of the Packs 2-32
Accessing the Database Home Page 2-34
Enterprise Manager Performance Pages 2-35
Viewing the Alert Log 2-37
Using Alert Log Information as an Aid in Tuning 2-38
User Trace Files 2-40
Background Processes Trace Files 2-41
Summary 2-42
Practice 2 Overview: Using Basic Tools 2-43
3 Using Automatic Workload Repository
Objectives 3-2
Automatic Workload Repository: Overview 3-3
Automatic Workload Repository Data 3-4
Workload Repository 3-5
Database Control and AWR 3-6
AWR Snapshot Purging Policy 3-7
AWR Snapshot Settings 3-8
Manual AWR Snapshots 3-9
Managing Snapshots with PL/SQL 3-10
Generating AWR Reports in EM 3-11
Generating AWR Reports in SQL*Plus 3-12
Reading the AWR Report 3-13
Snapshots and Periods Comparisons 3-14
Compare Periods: Benefits 3-15
Compare Periods: Results 3-16
Compare Periods: Report 3-17
Compare Periods: Load Profile 3-18
Compare Periods: Top Events 3-19
Summary 3-20
Practice 3 Overview: Using AWR-Based Tools 3-21
4 Defining Problems
Objectives 4-2
Defining the Problem 4-3
Limit the Scope 4-4
Setting the Priority 4-5
Top Wait Events 4-6
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v
Setting the Priority: Example 4-7
Top SQL Reports 4-8
Common Tuning Problems 4-9
Tuning Life Cycle Phases 4-11
Tuning During the Life Cycle 4-12
Application Design and Development 4-13
Testing: Database Configuration 4-14
Deployment 4-15
Production 4-16
Migration, Upgrade, and Environment Changes 4-17
ADDM Tuning Session 4-18
Performance Versus Business Requirements 4-19
Performance Tuning Resources 4-20
Filing a Performance Service Request 4-21
RDA Report 4-22
Monitoring and Tuning Tool: Overview 4-23
Summary 4-25
Practice 4 Overview: Identifying the Problem 4-26
5 Using Metrics and Alerts
Objectives 5-2
Metrics, Alerts, and Baselines 5-3
Limitation of Base Statistics 5-4
Typical Delta Tools 5-5
Oracle Database 11g Solution: Metrics 5-6
Benefits of Metrics 5-7
Viewing Metric History Information 5-8
Using EM to View Metric Details 5-9
Statistic Histograms 5-10
Histogram Views 5-11
Server-Generated Alerts 5-12
Database Control Usage Model 5-13
Setting Thresholds 5-14
Creating and Testing an Alert 5-15
Metric and Alert Views 5-16
View User-Defined SQL Metrics 5-17
Create User-Defined SQL Metrics 5-18
View User-Defined Host Metrics 5-19
Create User-Defined Host Metrics 5-20
Summary 5-21
Practice Overview 5: Working with Metrics 5-22
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6 Baselines
Objectives 6-2
Comparative Performance Analysis with AWR Baselines 6-3
Automatic Workload Repository Baselines 6-4
Moving Window Baseline 6-5
Baselines in Performance Page Settings 6-6
Baseline Templates 6-7
AWR Baselines 6-8
Creating AWR Baselines 6-9
Single AWR Baseline 6-10
Creating a Repeating Baseline Template 6-11
Managing Baselines with PL/SQL 6-12
Generating a Baseline Template for a Single Time Period 6-13
Creating a Repeating Baseline Template 6-14
Baseline Views 6-15
Performance Monitoring and Baselines 6-17
Defining Alert Thresholds Using a Static Baseline 6-19
Using EM to Quickly Configure Adaptive Thresholds 6-20
Changing Adaptive Threshold Settings 6-22
Summary 6-23
Practice 6: Overview Using AWR Baselines 6-24
7 Using AWR-Based Tools
Objectives 7-2
Automatic Maintenance Tasks 7-3
Maintenance Windows 7-4
Default Maintenance Plan 7-5
Automated Maintenance Task Priorities 7-6
Tuning Automatic Maintenance Tasks 7-7
ADDM Performance Monitoring 7-8
ADDM and Database Time 7-9
DBTime-Graph and ADDM Methodology 7-10
Top Performance Issues Detected 7-12
Database Control and ADDM Findings 7-13
ADDM Analysis Results 7-14
ADDM Recommendations 7-15
Database Control and ADDM Task 7-16
Changing ADDM Attributes 7-17
Retrieving ADDM Reports by Using SQL 7-18
Active Session History: Overview 7-19
Active Session History: Mechanics 7-20
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ASH Sampling: Example 7-21
Accessing ASH Data 7-22
Dump ASH to File 7-23
Analyzing the ASH Data 7-24
Generating ASH Reports 7-25
ASH Report Script 7-26
ASH Report: General Section 7-27
ASH Report Structure 7-28
ASH Report: Activity Over Time 7-29
Summary 7-30
Practice 7 Overview: Using AWR-Based Tools 7-31
8 Monitoring an Application
Objectives 8-2
What Is a Service? 8-3
Service Attributes 8-4
Service Types 8-5
Creating Services 8-6
Managing Services in a Single-Instance Environment 8-7
Everything Switches to Services 8-8
Using Services with Client Applications 8-9
Using Services with the Resource Manager 8-10
Services and Resource Manager with EM 8-11
Services and the Resource Manager: Example 8-12
Using Services with the Scheduler 8-13
Services and the Scheduler with EM 8-14
Services and the Scheduler: Example 8-16
Using Services with Parallel Operations 8-17
Using Services with Metric Thresholds 8-18
Changing Service Thresholds by Using EM 8-19
Services and Metric Thresholds: Example 8-20
Service Aggregation and Tracing 8-21
Top Services Performance Page 8-22
Service Aggregation Configuration 8-23
Service Aggregation: Example 8-24
Client Identifier Aggregation and Tracing 8-25
trcsess Utility 8-26
Service Performance Views 8-27
Summary 8-29
Practice 8 Overview: Using Services 8-30
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9 Identifying Problem SQL Statements
Objectives 9-2
SQL Statement Processing Phases 9-3
Parse Phase 9-4
SQL Storage 9-5
Cursor Usage and Parsing 9-6
SQL Statement Processing Phases: Bind 9-8
SQL Statement Processing Phases: Execute and Fetch 9-9
Processing a DML Statement 9-10
COMMIT Processing 9-12
Role of the Oracle Optimizer 9-13
Identifying Bad SQL 9-15
TOP SQL Reports 9-16
What Is an Execution Plan? 9-17
Methods for Viewing Execution Plans 9-18
Uses of Execution Plans 9-19
DBMS_XPLAN Package: Overview 9-20
EXPLAIN PLAN Command 9-22
EXPLAIN PLAN Command: Example 9-23
EXPLAIN PLAN Command: Output 9-24
Reading an Execution Plan 9-25
Using the V$SQL_PLAN View 9-26
V$SQL_PLAN Columns 9-27
Querying V$SQL_PLAN 9-28
V$SQL_PLAN_STATISTICS View 9-29
Querying the AWR 9-30
SQL*Plus AUTOTRACE 9-32
Using SQL*Plus AUTOTRACE 9-33
SQL*Plus AUTOTRACE: Statistics 9-34
SQL Trace Facility 9-35
How to Use the SQL Trace Facility 9-37
Initialization Parameters 9-38
Enabling SQL Trace 9-40
Disabling SQL Trace 9-41
Formatting Your Trace Files 9-42
TKPROF Command Options 9-43
Output of the TKPROF Command 9-45
TKPROF Output with No Index: Example 9-50
TKPROF Output with Index: Example 9-51
Generate an Optimizer Trace 9-52
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Summary 9-53
Practice Overview 9: Using Execution Plan Utilities 9-54
10 Influencing the Optimizer
Objectives 10-2
Functions of the Query Optimizer 10-3
Selectivity 10-5
Cardinality and Cost 10-6
Changing Optimizer Behavior 10-7
Using Hints 10-8
Optimizer Statistics 10-9
Extended Statistics 10-10
Controlling the Behavior of the Optimizer with Parameters 10-11
Enabling Query Optimizer Features 10-13
Influencing the Optimizer Approach 10-14
Optimizing SQL Statements 10-15
Access Paths 10-16
Choosing an Access Path 10-17
Full Table Scans 10-18
Row ID Scans 10-20
Index Operations 10-21
B*Tree Index Operations 10-22
Bitmap Indexes 10-23
Bitmap Index Access 10-24
Combining Bitmaps 10-25
Bitmap Operations 10-26
Join Operations 10-27
Join Methods 10-28
Nested Loop Joins 10-29
Hash Joins 10-31
Sort-Merge Joins 10-32
Join Performance 10-34
How the Query Optimizer Chooses Execution Plans for Joins 10-35
Sort Operations 10-37
Tuning Sort Performance 10-38
Reducing the Cost 10-39
Index Maintenance 10-40
Dropping Indexes 10-42
Creating Indexes 10-43
SQL Access Advisor 10-44
Table Maintenance for Performance 10-45
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Table Reorganization Methods 10-46
Summary 10-47
Practice 10 Overview: Influencing the Optimizer 10-48
11 Using SQL Performance Analyzer
Objectives 11-2
Real Application Testing: Overview 11-3
Real Application Testing: Use Cases 11-4
SQL Performance Analyzer: Process 11-5
Capturing the SQL Workload 11-7
Creating a SQL Performance Analyzer Task 11-8
SQL Performance Analyzer: Tasks 11-9
Optimizer Upgrade Simulation 11-10
SQL Performance Analyzer Task Page 11-11
Comparison Report 11-12
Comparison Report SQL Detail 11-13
Tuning Regressing Statements 11-14
Preventing Regressions 11-16
Parameter Change Analysis 11-17
Guided Workflow Analysis 11-18
SQL Performance Analyzer: PL/SQL Example 11-19
SQL Performance Analyzer: Data Dictionary Views 11-21
Summary 11-22
Practice 11: Overview 11-23
12 SQL Performance Management
Objectives 12-2
Maintaining SQL Performance 12-3
Maintaining Optimizer Statistics 12-4
Automated Maintenance Tasks 12-5
Statistic Gathering Options 12-6
Setting Statistic Preferences 12-7
Restore Statistics 12-9
Deferred Statistics Publishing: Overview 12-10
Deferred Statistics Publishing: Example 12-12
Automatic SQL Tuning: Overview 12-13
SQL Statement Profiling 12-14
Plan Tuning Flow and SQL Profile Creation 12-15
SQL Tuning Loop 12-16
Using SQL Profiles 12-17
SQL Tuning Advisor: Overview 12-18
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Using the SQL Tuning Advisor 12-19
SQL Tuning Advisor Options 12-20
SQL Tuning Advisor Recommendations 12-21
Using the SQL Tuning Advisor: Example 12-22
Using the SQL Access Advisor 12-23
View Recommendations 12-25
View Recommendation Details 12-26
SQL Plan Management: Overview 12-27
SQL Plan Baseline: Architecture 12-28
Loading SQL Plan Baselines 12-30
Evolving SQL Plan Baselines 12-31
Important Baseline SQL Plan Attributes 12-32
SQL Plan Selection 12-34
Possible SQL Plan Manageability Scenarios 12-36
SQL Performance Analyzer and SQL Plan Baseline Scenario 12-37
Loading a SQL Plan Baseline Automatically 12-38
Purging SQL Management Base Policy 12-39
Enterprise Manager and SQL Plan Baselines 12-40
Summary 12-41
Practice 12: Overview Using SQL Plan Management 12-42
13 Using Database Replay
Objectives 13-2
Using Database Replay 13-3
The Big Picture 13-4
System Architecture: Capture 13-5
System Architecture: Processing the Workload 13-7
System Architecture: Replay 13-8
Capture Considerations 13-9
Replay Considerations: Preparation 13-10
Replay Considerations 13-11
Replay Options 13-12
Replay Analysis 13-13
Database Replay Workflow in Enterprise Manager 13-15
Capturing Workload with Enterprise Manager 13-16
Capture Wizard: Plan Environment 13-17
Capture Wizard: Options 13-18
Capture Wizard: Parameters 13-19
Viewing Capture Progress 13-20
Viewing Capture Report 13-21
Export Capture AWR Data 13-22
Oracle Internal & Oracle Academy Use Only
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Viewing Workload Capture History 13-23
Processing Captured Workload 13-24
Using the Preprocess Captured Workload Wizard 13-25
Using the Replay Workload Wizard 13-26
Replay Workload: Prerequisites 13-27
Replay Workload: Choose Initial Options 13-28
Replay Workload: Customize Options 13-29
Replay Workload: Prepare Replay Clients 13-30
Replay Workload: Client Connections 13-31
Replay Workload: Replay Started 13-32
Viewing Workload Replay Progress 13-33
Viewing Workload Replay Statistics 13-34
Packages and Procedures 13-36
Data Dictionary Views: Database Replay 13-37
Database Replay: PL/SQL Example 13-38
Calibrating Replay Clients 13-40
Summary 13-41
Practice 13: Overview 13-42
14 Tuning the Shared Pool
Objectives 14-2
Shared Pool Architecture 14-3
Shared Pool Operation 14-4
The Library Cache 14-5
Latch and Mutex 14-7
Latch and Mutex: Views and Statistics 14-9
Diagnostic Tools for Tuning the Shared Pool 14-11
AWR/Statspack Indicators 14-13
Load Profile 14-14
Instance Efficiencies 14-15
Top Waits 14-16
Time Model 14-17
Library Cache Activity 14-19
Avoid Hard Parses 14-20
Are Cursors Being Shared? 14-21
Sharing Cursors 14-23
Adaptive Cursor Sharing: Example 14-25
Adaptive Cursor Sharing Views 14-27
Interacting with Adaptive Cursor Sharing 14-28
Avoiding Soft Parses 14-29
Sizing the Shared Pool 14-30
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Shared Pool Advisory 14-31
Shared Pool Advisor 14-33
Avoiding Fragmentation 14-34
Large Memory Requirements 14-35
Tuning the Shared Pool Reserved Space 14-37
Keeping Large Objects 14-39
Data Dictionary Cache 14-41
Dictionary Cache Misses 14-42
SQL Query Result Cache: Overview 14-43
Managing the SQL Query Result Cache 14-44
Using the RESULT_CACHE Hint 14-46
Using the DBMS_RESULT_CACHE Package 14-47
Viewing SQL Result Cache Dictionary Information 14-48
SQL Query Result Cache: Considerations 14-49
UGA and Oracle Shared Server 14-50
Large Pool 14-51
Tuning the Large Pool 14-52
Summary 14-53
Practice Overview 14: Tuning the Shared Pool 14-54
15 Tuning the Buffer Cache
Objectives 15-2
Oracle Database Architecture 15-3
Buffer Cache: Highlights 15-4
Database Buffers 15-5
Buffer Hash Table for Lookups 15-6
Working Sets 15-7
Tuning Goals and Techniques 15-9
Symptoms 15-11
Cache Buffer Chains Latch Contention 15-12
Finding Hot Segments 15-13
Buffer Busy Waits 15-14
Calculating the Buffer Cache Hit Ratio 15-15
Buffer Cache Hit Ratio Is Not Everything 15-16
Interpreting Buffer Cache Hit Ratio 15-17
Read Waits 15-19
Free Buffer Waits 15-21
Solutions 15-22
Sizing the Buffer Cache 15-23
Buffer Cache Size Parameters 15-24
Dynamic Buffer Cache Advisory Parameter 15-25
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Buffer Cache Advisory View 15-26
Using the V$DB_CACHE_ADVICE View 15-27
Using the Buffer Cache Advisory with EM 15-28
Caching Tables 15-29
Multiple Buffer Pools 15-30
Enabling Multiple Buffer Pools 15-32
Calculating the Hit Ratio for Multiple Pools 15-33
Multiple Block Sizes 15-35
Multiple Database Writers 15-36
Multiple I/O Slaves 15-37
Use Multiple Writers or I/O Slaves 15-38
Private Pool for I/O Intensive Operations 15-39
Automatically Tuned Multiblock Reads 15-40
Flushing the Buffer Cache (for Testing Only) 15-41
Summary 15-42
Practice 15: Overview Tuning the Buffer Cache 15-43
16 Tuning PGA and Temporary Space
Objectives 16-2
SQL Memory Usage 16-3
Performance Impact 16-4
Automatic PGA Memory 16-5
SQL Memory Manager 16-6
Configuring Automatic PGA Memory 16-8
Setting PGA_AGGREGATE_TARGET Initially 16-9
Monitoring SQL Memory Usage 16-10
Monitoring SQL Memory Usage: Examples 16-12
Tuning SQL Memory Usage 16-13
PGA Target Advice Statistics 16-14
PGA Target Advice Histograms 16-15
Automatic PGA and Enterprise Manager 16-16
Automatic PGA and AWR Reports 16-17
Temporary Tablespace Management: Overview 16-18
Temporary Tablespace: Best Practice 16-19
Configuring Temporary Tablespace 16-20
Temporary Tablespace Group: Overview 16-22
Temporary Tablespace Group: Benefits 16-23
Creating Temporary Tablespace Groups 16-24
Maintaining Temporary Tablespace Groups 16-25
View Tablespace Groups 16-26
Monitoring Temporary Tablespace 16-27
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Temporary Tablespace Shrink 16-28
Tablespace Option for Creating Temporary Table 16-29
Summary 16-30
Practice Overview 16: Tuning PGA Memory 16-31
17 Automatic Memory Management
Objectives 17-2
Oracle Database Architecture 17-3
Dynamic SGA 17-4
Granule 17-5
Memory Advisories 17-6
Manually Adding Granules to Components 17-7
Increasing the Size of an SGA Component 17-8
Automatic Shared Memory Management: Overview 17-9
SGA Sizing Parameters: Overview 17-10
Dynamic SGA Transfer Modes 17-11
Memory Broker Architecture 17-12
Manually Resizing Dynamic SGA Parameters 17-13
Behavior of Auto-Tuned SGA Parameters 17-14
Behavior of Manually Tuned SGA Parameters 17-15
Using the V$PARAMETER View 17-16
Resizing SGA_TARGET 17-17
Disabling Automatic Shared Memory Management 17-18
Configuring ASMM 17-19
SGA Advisor 17-20
Monitoring ASMM 17-21
Automatic Memory Management: Overview 17-22
Oracle Database Memory Parameters 17-24
Automatic Memory Parameter Dependency 17-25
Enabling Automatic Memory Management 17-26
Monitoring Automatic Memory Management 17-27
DBCA and Automatic Memory Management 17-29
Summary 17-30
Practice 17: Overview Using Automatic Memory Tuning 17-31
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18 Tuning Segment Space Usage
Objectives 18-2
Space Management 18-3
Extent Management 18-4
Locally Managed Extents 18-5
Large Extents: Considerations 18-6
How Table Data Is Stored 18-8
Anatomy of a Database Block 18-9
Minimize Block Visits 18-10
The DB_BLOCK_SIZE Parameter 18-11
Small Block Size: Considerations 18-12
Large Block Size: Considerations 18-13
Block Allocation 18-14
Free Lists 18-15
Block Space Management 18-16
Block Space Management with Free Lists 18-17
Automatic Segment Space Management 18-19
Automatic Segment Space Management at Work 18-20
Block Space Management with ASSM 18-22
Creating an Automatic Segment Space Management Segment 18-23
Migration and Chaining 18-24
Guidelines for PCTFREE and PCTUSED 18-26
Detecting Migration and Chaining 18-27
Selecting Migrated Rows 18-28
Eliminating Migrated Rows 18-29
Shrinking Segments: Overview 18-31
Shrinking Segments: Considerations 18-32
Shrinking Segments by Using SQL 18-33
Segment Shrink: Basic Execution 18-34
Segment Shrink: Execution Considerations 18-35
Using EM to Shrink Segments 18-36
Table Compression: Overview 18-37
Table Compression Concepts 18-38
Using Table Compression 18-39
Summary 18-40
19 Tuning I/O
Objectives 19-2
I/O Architecture 19-3
File System Characteristics 19-4
I/O Modes 19-5
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Direct I/O 19-6
Bandwidth Versus Size 19-7
Important I/O Metrics for Oracle Databases 19-8
I/O Calibration and Enterprise Manager 19-10
I/O Calibration and the PL/SQL Interface 19-11
I/O Statistics: Overview 19-13
I/O Statistics and Enterprise Manager 19-14
Stripe and Mirror Everything 19-16
Using RAID 19-17
RAID Cost Versus Benefits 19-18
Should I Use RAID 1 or RAID 5? 19-20
Diagnostics 19-21
Database I/O Tuning 19-22
What Is Automatic Storage Management? 19-23
Tuning ASM 19-24
How Many Disk Groups per Database 19-25
Which RAID Configuration for Best Availability? 19-26
ASM Mirroring Guidelines 19-27
ASM Striping Granularity 19-28
What Type of Striping Works Best? 19-29
ASM Striping Only 19-30
Hardware RAID Striped LUNs 19-31
ASM Guidelines 19-32
ASM Instance Initialization Parameters 19-33
Dynamic Performance Views 19-34
Monitoring Long-Running Operations by Using V$ASM_OPERATION 19-36
ASM Instance Performance Diagnostics 19-37
ASM Performance Page 19-38
Database Instance Parameter Changes 19-39
ASM Scalability 19-40
Summary 19-41
20 Performance Tuning Summary
Objectives 20-2
Necessary Initialization Parameters with Little Performance Impact 20-3
Important Initialization Parameters with Performance Impact 20-4
Sizing Memory Initially 20-6
Database High Availability: Best Practices 20-7
Undo Tablespace: Best Practices 20-8
Temporary Tablespace: Best Practices 20-9
General Tablespace: Best Practices 20-11
Internal Fragmentation Considerations 20-12
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Block Size: Advantages and Disadvantages 20-13
Automatic Checkpoint Tuning 20-14
Sizing the Redo Log Buffer 20-15
Sizing Redo Log Files 20-16
Increasing the Performance of Archiving 20-17
Automatic Statistics Gathering 20-19
Automatic Statistics Collection: Considerations 20-20
Commonly Observed Wait Events 20-21
Additional Statistics 20-22
Top 10 Mistakes Found in Customer Systems 20-23
Summary 20-25
Appendix A: Practices and Solutions
Appendix B: Using Statspack
Index

Coalesce free space in blocks

Hi
Assume I insert a row into the block and there are small free spaces inside the block.
Does oracle automatically coalesce the free spaces in the block for my new row ?

Assume I insert a row into the block and there are small free spaces inside the block.If there is small free space inside the block the row will be inserted into new block. The block will allocated from the free list of the tablespace for that table. If the records are freed from the block such as delete than PCTFREE and PCTUSED comes into account. PCTFREE is limitation upto which the block should be free and PCTUSED is the pecentage of space upto which the blocks to be used.
Does oracle automatically coalesce the free spaces in the block for my new row ?Free spaces are not coalesced from blocks its from the extents of the table. If there is free blocks before HWM(High Water Mark) then the block is allocated to new row.
Thanks.
Edited by: virendra.k on Aug 1, 2009 4:20 PM

Insert performance

Hi guys,
I have a web application running on Oracle 9.2.0.7. This application inserts one row in a specific table for auditing purposes in every click of the user.
The problem is that some periods of the day there are too many users using that app and there is too many inserts in the audit table.
So, I am doing some configurations to improve performance for that particular process.
1) Created a 16K tablespace and move the audit table
2) Altered the audit table with PCTFREE and PCTUSED to 0
3) Altered the audit table with FREELIST = 2
4) Certified that there is no triggers or idexes on that table.
My question is: There is another thing that I can do? What about using hint APPEND to the insert statement on the application?
Thanks in advance,
Paulo.

Thank you Jaffar!
I read an article of Dan Burleson about using multiple freelist x ASSM (http://www.rampant-books.com/phys_81.htm) which tells that using multiple freelist can be better than ASSM. But, I am thinking now in using ASSM, as you suggest. It will be, also, more easy to handle the tablespace, right?
So, If I will use the ASSM, I will not be able to configure the PCTFREE and PCTUSED, right?
Have you think of partitioning this table? This will give you good results mainly for the tables which large amount of dataI am on Standard Edition! Not able to use the Partitioning...
APPEND hint is used for direct load/inserts.So, it cannot be used in a statement default? "insert into xxxx values xxxx" ?
Thanks again,
Paulo.

Error in impdp with dblink

Hi all,
I have small problem. I am trying importing schema uing a network link.
I create dblink on target database and start import with this parameters:
userid="SCAN@odtest"
network_link=ODLINK
LOGFILE=scan_imp.log
DIRECTORY=DPDIR
SCHEMAS="SCAN"
TABLE_EXISTS_ACTION=replace
EXCLUDE=INDEX_STATISTICS
EXCLUDE=TABLE_STATISTICS
CONTENT=ALLbut I get error.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning option
Starting "SCAN"."SYS_IMPORT_SCHEMA_01": SCAN/********@odtest parfile=scan.par
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 0 KB
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/TYPE/TYPE_SPEC
Processing object type SCHEMA_EXPORT/TABLE/TABLE
ORA-39083: Object type TABLE:"SCAN"."SCANIMAGE" failed to create with error:
ORA-14460: only one COMPRESS or NOCOMPRESS clause may be specified
Failing sql is:
CREATE TABLE "SCAN"."SCANIMAGE" ("ID" NUMBER(10,0) NOT NULL ENABLE, "IMAGE" BLOB, "TYPE" VARCHAR2(10 BYTE), "SCAN_DATE" TIMESTAMP (6) DEFAULT sysdate NOT NULL ENABLE) PCTFREE 10 PCTUSED 40 INITRANS 1 MAXTRANS 255 STORAGE( BUFFER_POOL DEFAULT FLASH_CACHE DEFAULT CELL_FLASH_CACHE DEFAULT) TABLESPACE "SCAN" LOB ("IMAGE") STORE AS BASICFILE (ENABLE S
. . imported "SCAN"."OBJECT" 4 rows
...User SCAN have grants to create table. Import stopped only on this table(partitioned).

I've seen this error as well and was able to work around it by running the datapump import with:
transform=segment_attributes:n
This causes impdp to NOT include the COMPRESS/NOCOMPRESS setting. However, you lose a lot of other settings as well. You will lose the LOGGING clause, the PCTFREE and PCTUSED settings, INITTRANS, MAXTRANS, the whole storage clause, and perhaps worst of all the TABLESPACE clause.

PCTFREE and PCTUSED

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