IOncrease size of buffer pool and PGA

Dear All,
Currently my DB is on Automatic Memory Management,
I want to increase the size of Buffer cache and PGA, so do I need to move the DB out of Automatic Memory Managemen and manually manage the memory?
Please help
Thanks

Wrong forum. This is for SQL and PL/SQL questions.
Try General Database Discussions

Similar Messages

Query about Keep Buffer Pool and Recycle Buffer Pool

What will Keep Buffer Pool and Recycle Buffer Pool contains actually in Database Buffer Cache, specially what type of objects? I know the definitions but need to know the practical aspects about them.

918868 wrote:
What will Keep Buffer Pool and Recycle Buffer Pool contains actually in Database Buffer Cache, specially what type of objects? I know the definitions but need to know the practical aspects about them.I believe you have already got the answer from the experts. Just to echo the same, in any cache, either Buffer Cache(default), Keep or Recycle, its going to be data buffers which are actually the placeholders for the data blocks that are available on the disk. The default cache is going to throw away the lesser used buffers as fast as possible. And if you don't want this to happen, you can use either of the other two, indepandant caches-Recycle and Keep. The keep cache , as the name suggests would keep the buffers in it for a more loonger duration compared to the default cache. This probably would be a better idea when you know that some buffers are meant to be reused again and again. Recycle is going tobe for those, which are very seldom used and you don't want them to choke up the caches at all. For the buffers kept in the Recycle cache, they would be thrown out almost instantly.
Read the link that's given to you. It contains a lot of stuff that would further make things clear.
Aman....

Increase the SGA and PGA size

Hello Guru,
How do i check what is my SGA and PGA..I am using TOAD..
I need to increase the SGA and PGA size...Please help..
I have a table having 200 million records, all indexes are there for the column..But it hang on in the debugging mode and also compile mode..
So i believe, I need to increase the SGA and PGA size...
Thanks,
Haraprasad...

805936 wrote:
Hello Guru,
How do i check what is my SGA and PGA..I am using TOAD..
I need to increase the SGA and PGA size...Please help..
The current size for both SGA and PGA can be shown depending on the version of the db. For 10g, the SGA size is shown by sga_target parameter and PGA size is shown by pga_aggregate_target parameter. For 11g, the parameter memory_target sets them both.
I have a table having 200 million records, all indexes are there for the column..But it hang on in the debugging mode and also compile mode..
So i believe, I need to increase the SGA and PGA size...No, IMO, your believe doesn't hold much base as the evidence that you have used is insufficient. What is the debugging mode or compile mode ? For what purpose you are using these modes? 200 million is not a very large number if you ask me. Tell us your db version and based on it, generate a Statspack or AWR report and post here.
HTH
Aman....

Clearing Data Buffer Pools

Is it possible to clear the buffer pool in Oracle without bouncing the database? We are configuring our database to use the keep buffer pools, and I wanted to test the performance improvements with pinning different tables into the keep buffer. Unfortunately the only way I can clear the buffer is to bounce the database, which disrupts several other people. I was hoping there was something like the "alter system flush shared_pool" to do this.
Any help would be greatly appreciated...

Is it possible to clear the buffer pool in Oracle without bouncing the database? We are configuring our database to use the keep buffer pools, and I wanted to test the performance improvements with pinning different tables into the keep buffer. Unfortunately the only way I can clear the buffer is to bounce the database, which disrupts several other people. I was hoping there was something like the "alter system flush shared_pool" to do this.
Any help would be greatly appreciated... i guess there is no straight forward method like 'flush shared pool'
maybe you can try running a full table scan or a cartesian join on two large tables
which will flush the buffers of the tables that you are trying to tune.
this is exactly the situation why you want to go for 'keep' buffer pool.

Why should recyle cache should be smaller then buffer pool.

Hi,
I am going through a documnetaion, where i read that your recyle cahche should be smaller then your buffer pools and it should be use buffers more quickly then .the idea behiend having a recycle cache is that if the sql statment is tuned then put the large segmant in recycle cahche so it does not effect others segmant in cache to edge out more frequentlly then it should be?now i wanted to know that what is the reason of taknig recyle cache smaller then buffer pool and why it should use buffers more quickly then the default buffer pool?and am i putting the right picture of recycle cache ?
thanks and regards
Alok Kumar...

Hi Alok,
I asume you mean by buffer the default buffer cache, right ?
The only idea why a recycle buffer cache should be smaller than another cache can be for memory reasons: not to spend to much memory for cache. But I cannot image this should be a general guide all all kind of application ...
On the other I have the impression that your picture of the recycle cache is a little bit different to my's picture:
I only will use different caches if have very different tables and indexes (not sql stmts). Each table and index will be assigned to a cache, e.g. the default cache and the recycle cache. The goal is, as you described, to prtend small tables and indexes from ageing out of the default cache. But the access to the recycle cache is as fast as to the default cache: both are in memory. The only diference is the administration of the blocks into the cache. The recycle cache has an administration of the blocks much easier and faster as the other one.
I hope this will give you some answers (and porb. some new questions) ...
greets,
Rainer

Buffer pool keep and multiple db block sizes

I have a tablespace with 8k block size (database default) and a tablespace with 16k block size. I have db_cache_size and db_16k_cache_size set (obviously).
Also i have buffer cache keep set in the database.
Question: If a table is placed in a tablespace with 16k block size, and it's buffer pool is keep, does it end up in the keep pool (like tables from 8k tablsepace and keep pool set), or it ends in 16k buffer?

You can find in the following online manual
http://download-west.oracle.com/docs/cd/B19306_01/server.102/b14220/memory.htm#i16408

Default Buffer Pool Busy Waits and Default Buffer Pool Hit Ratio

Hi experts,
I am having oracle database with version 11gR2 on windows server 2003 platform.
I am continuously getting alerts related to "Default Buffer Pool Busy Waits" and "Default Buffer Pool Hit Ratio."
I have fired some of the queries(which contain view like v$session_wait) to get information of sessions that causing the same issue,but unable to get it.
Please help me to resolve the same issue.

Hi - Try this query for Buffer busy wait
COL class FORM a10
COL total_waits FORM 9,999,999,999
COL "WAITS %" FORM 9999999
COL time_waited FORM 9999999
COL "TIME %" FORM 9999999
COL event FORM a24
COL avg_wait FORM 9999.99
SELECT a.event event, substr(c.wait_class,1,9) class,
a.total_waits total_waits, a.time_waited/100 time_waited,
a.average_wait avg_wait
-- a.average_wait/100 avg_wait -- displays seconds instead of 100s
FROM v$system_event a, v$event_name b, v$system_wait_class c
WHERE a.event_id=b.event_id
AND b.wait_class#=c.wait_class#
AND a.time_waited/100 > 0
AND (event LIKE '%HW%' OR event = 'buffer busy waits')
-- AND c.wait_class in ('Application','Concurrency','User I/O')
ORDER BY 1 DESC;

KEEP and RECYCLE buffer pools question...

About the DB buffer cache's two optional buffer pools: KEEP and RECYCLE pools.
If i want a table to be kept in KEEP buffer pool, can i specify that in CREATE TABLE or ALTER TABLE syntax? Or is it possible only at tablespace level?

HI,
You can keep tables at keep pool by specifying storage (buffer_pool keep) parameter.

Buffer pool size

Oracle 9.2.0.4.0
java 1.4.2
Hi,
How can I set the buffer pool size in oracle 9i?
Thanks
JN

DB_CACHE_SIZE
Parameter type
Big integer
Syntax
DB_CACHE_SIZE = integer [K | M | G]
Default value
48 MB, rounded up to the nearest granule size
Parameter class
Dynamic: ALTER SYSTEM
DB_CACHE_SIZE specifies the size of the DEFAULT buffer pool for buffers with the primary block size (the block size defined by the DB_BLOCK_SIZE parameter).
The value must be at least the size of one granule (smaller values are automatically rounded up to the granule size). A value of zero is illegal because zero is the size of the DEFAULT pool for the standard block size, which is the block size for the SYSTEM tablespace.
[email protected]
Joel P�rez

Script to find out table and index candidates to keep in the buffer pool

I am looking for a script to find out tables and indexes to keep in the buffer pool.
Could you help me on this ?
thanks...
Markus

this is more of a open question. As you know ur data well. We do not know whats ur data. cachin tables in buffer pool is okay, but it might age out after not being used...instead you can use the KEEP POOL...to cache small tables/popular tables into the keep pool...as keep pool guarantees full caching .....
here are some links on keep pool cacheing
http://download.oracle.com/docs/cd/B19306_01/server.102/b14211/memory.htm#sthref410
http://www.dba-oracle.com/oracle_tips_cache_small_fts.htm
http://www.dba-oracle.com/t_script_automate_keep_pool_tables_indexes.htm
http://www.dba-oracle.com/oracle_news/news_caching_keep_pool_large_objects_clob_blob.htm
Edited by: user630084 on Apr 8, 2009 5:48 AM

No free buffers available in buffer pool default

We encounter this error ORA00379 No free buffers available in buffer pool default with one of our online transaction system.
Initially, the errors occur once every 30 sec, and became less frequent (about twice a day) after the buffers has been increased to the size of Oracle's default medium size database.
Currently, the system is under testing and we have 4 staffs using the same userid to send transactions. Furthermore the size of each transaction is about 3-5mb. Will these issues actually caused Oracle to run out of free buffer spaces?
Please advise.
Thankyou,

Kenny
I think your are running your server as dedicated server. Make it multi-threaded server if it is applicable. It will use the resources more efficiently. Otherwise, you have to set your pool size, prespawn, etc to their maximums.
Regards

Db_keep_cache_size shows 0 when i keep object in KEEP buffer pool !

Dear Frineds ,
I use Oracle 10g . Form the oracle 10g documentaiton, I get the following information regarding ASMM (Automatic Shared Memory Management) :
The following pools are manually sized components and are not affected by Automatic Shared Memory Management:
Log buffer
Other buffer caches (such as KEEP, RECYCLE, and other non-default block size)
Fixed SGA and other internal allocations
Now plz see the following examle :
1) SQL> select sum(bytes)/1024/1024 " SGA size used in MB" from v$sgastat where name!='free memory';
SGA size used in MB
247.09124
2) SQL> show parameter keep_
NAME TYPE VALUE
db_keep_cache_size big integer 0 (Here db_keep_cache_size is 0 )
3) Now I keep the scott's dept table to KEEP cache :
SQL> select owner,segment_type,segment_name,buffer_pool from dba_segments where buffer_pool != 'DEFAULT';
no rows selected
SQL> alter table scott.dept storage(BUFFER_POOL KEEP);
Table altered.
SQL> select owner,segment_type,segment_name,buffer_pool from dba_segments where buffer_pool != 'DEFAULT';
OWNER SEGMENT_TYPE SEGMENT_NAME
SCOTT TABLE DEPT
4)
After doing this , I have to see the following parameter :
SQL> show parameter keep
NAME TYPE VALUE
db_keep_cache_size big integer 0
SQL> select sum(bytes)/1024/1024 " SGA size used in MB" from v$sgastat where name!='free memory';
SGA size used in MB
246.76825
Here I see that my sga is used but "db_keep_cache_size" still shows the '0' .
Can u plz explain why this parameter value shows '0' now ?
Thx in advance ... ...

Hi,
I am not sure I have understood the question fully but if you are trying to monitor usage of the buffer pools you should use some of the dynamic views like in the example query below. If this is not what you are interested in let me know.
SELECT NAME, BLOCK_SIZE, SUM(BUFFERS)
FROM V$BUFFER_POOL
GROUP BY NAME, BLOCK_SIZE
HAVING SUM(BUFFERS) > 0;

How to configure params for buffer pool for named data cache?

when create a named data cache on ase 12.5, it will setup 2K I/O buffer pool by default with Configured size=0, wash size = 60M
1. if 2K can be changed to 8K for this buffer pool?
2. If add another 16k buffer pool, should Affected Pool be changed to the right pool?
3. How to decide then pagesize, configured size and wash size for a buffer pool? Are they part of total memory size allocated for this cache?

> 1. if 2K can be changed to 8K for this buffer pool?
You should be able to create an 8K i/o pool, then drop the 2k pool by setting its size to 0.
> 2. If add another 16k buffer pool, should Affected Pool be changed to the right pool?
If you don't specify the Affected Pool (when calling sp_poolconfig), the procedure uses the pool with the smallest i/o. So if you had an 8k but not had dropped the 2k, the space for the new 16k pool would come from the 8k pool.
> 3. How to decide then pagesize, configured size and wash size for a buffer pool? Are they part of total memory size allocated for this cache?
The wash is included in the pool. I don't think it usually needs to be adjusted.
Which page size pools to have will depend on how the cache is used. Tables with a clustered index that have a lot of range queries will benefit from larger page size pools, as will text/image/java. Syslogs is said to do well on a 4k pool.
-bret

Buffer pool Cache is two low .

Dear Experts ,
All of the sudden the producation database buffer pool cacheing had fallen down to 35 %
select
100*(1 - (v3.value / (v1.value + v2.value))) "Cache Hit Ratio [%]"
from
v$sysstat v1, v$sysstat v2, v$sysstat v3
where
v1.name = 'db block gets' and
v2.name = 'consistent gets' and
v3.name = 'physical reads';
When i run this script i am getting '93.9% hit
but
select name,100 - round ((physical_reads/(db_block_gets+consistent_gets))*1
"hit ratio" from v$buffer_pool_statistics;
NAME hit ratio
DEFAULT 34.87
my hit ratio is also about 93% but sudden my database perforamce gone very low .
please advise your valuable suggestion .

> {quote:title=user640913 wrote:}{quote}
> Thanks for the Response .
> My DB version 10.2.0.4 on AIX 5.3
>
> there are some lending users . that cause this please help me how to find the stmt that making a troble and to solve it .
> i am copyiing the AWR REPORT with this mail .
>
> AWR REPORT LOAD PROFILE .
>
>                        Per Second                      PerTransaction I
> Redo size:             89,912.03                            13,411.58
> Logical reads:           55,554.6                             8,285.20
> Block changes:        553.50                                 82.56
> Physical reads:        15,842.52                              2,318.37
> Physical writes:        20.93                                      3.12
> User calls:              269.32                                      40.17
> Parses:                 138.35                                      20.64
> Hard parses:          4.13                                         0.62
> Logons:                0.81                                          0.09
> Executes:             356.3                                       53.23
> ransactions:          6.70                                        0
> [eBlocks changed per Read: 1.00 Recursive Call %: 70.83
> Rollback per transaction %: 3.84 Rows per Sort: 103.67
>
Since you're licensed to run the AWR why are you bothering with something as silly as that SQL for the "buffer cache hit ratio" !
You need to compare a "pre-problem" AWR with the current AWR reports to see if you can spot the changes that might be the significant ones, but based purely on the Load Profile that you have shown, you're not really doing much work, but you're doing it the hard way. The figures that stand out are:
{code}
Logical reads:           55,554.6                             8,285.20
Physical reads:        15,842.52                              2,318.37
{code}
You can check the instance statistics to learn more about what type of read activity is generating these physical reads, and work out whether (a) it's sensible and (b) it's supportable on your number of disc. Having said that - take a look at the "SQL ordered by Reads" section of the report to see which SQL statements are responsible for most of the reads, get the historic plans from the AWR and then work out why the plan changed and how to produce a better plan.
See my note below that explains why my quote of your results is tidier than your original.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
To post code, statspack/AWR report, execution plans or trace files, start and end the section with the tag {noformat}{code}{noformat} (lowercase, curly brackets, no spaces) so that the text appears in {code}fixed format{code}.
There is a +"Preview"+ tab at the top of the text entry panel. Use this to check what your message will look like before you post the message. If it looks a complete mess you're unlikely to get a response. (Click on the +"Plain text"+ tab if you want to edit the text to tidy it up.)

Buffer pool parameter vs LRU/MRU

Dear Friends,
I know that in the database buffer cache , the following parameters define the sizes of the caches for buffers :
–     Default : DB_CACHE_SIZE
–     Keep : DB_KEEP_CACHE_SIZE
–     Recycle: DB_RECYCLE_CACHE_SIZE
And also I know LRU and MRU also works in this regards .Now my ques is , when the "keep pool" and " the "buffer pool" is on then LRU and MRU are active ?
Both the above 3 pools and (LRU+MRU) is working together ? I have confusion about that . plz help .. ..

I am getting buffer busy waits on some tables.
Users are not experiencing any problem.Looks like you got bit by the CTD troll while sleeping.
Note also that (if I'm reading the report alright) out of 23 mins you have 6 seconds accounted to buffer busy waits.
Read the sample chapter here.

IOncrease size of buffer pool and PGA

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