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.
Similar Messages
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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 -
Is there any way exsit to drop database specific data buffer from buffer pool.
hi,
Is there any way exist to drop one data buffer(DBCC DROPCLEANBUFFERS)
.like DBCC FLUSHPROCINDB( db_id )
yours sincerely.hi,
Is there any way exist to drop one data buffer(DBCC DROPCLEANBUFFERS
You can selectively flush plans from buffer pool, not all cache objects related to database . See
DBCC FREEPROCCACHE
Please mark this reply as answer if it solved your issue or vote as helpful if it helped so that other forum members can benefit from it
My Technet Wiki Article
MVP -
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.... -
How to clear a buffer memory in a report program?
Hi Gurus,
How to clear a buffer memory in a report program?
Regards,
Amit Kumar SinghYes i am using USER__COMMAND like this
FORM USER_COMMAND *
FORM user_command USING u_ucomm TYPE sy-ucomm
us_selfield TYPE slis_selfield. "#EC CALLED
data : l_memory_id(20) type c value 'BSVA_BUFFER'.
free memory ID l_memory_id.
CASE u_ucomm.
WHEN gc_refresh.
PERFORM clear_data.
CONCATENATE '-' p_months INTO p_months.
PERFORM populate_z01. "List of Plants and Materials
PERFORM populate_z02. "List of Periods and dates
PERFORM populate_z03. "Report Contents
PERFORM add_data.
us_selfield-refresh = c_x.
us_selfield-col_stable = c_x.
us_selfield-row_stable = c_x.
ENDCASE.
ENDFORM. "user_command
FORM PF_STATUS_SET *
FORM pf_status_set USING ut_extab TYPE slis_t_extab. "#EC CALLED
DELETE ut_extab WHERE fcode = gc_refresh.
SET PF-STATUS 'STANDARD_FULLSCREEN' OF PROGRAM 'SAPLKKBL'
EXCLUDING ut_extab.
ENDFORM. "pf_status_set
Where gc_refresh is defined as
constants : gc_refresh TYPE syucomm VALUE '&REFRESH'. -
Is there any way that I could signal daat buffer cache to write all data to data files if amount of dirty blocks reach say 50 Mb.
Iam processing with BLOBS, one blob at a time, some of which has sizes exceeeding 100 Mb and the diffcult thing is that I cannot write to disk until the whoile blob is finished as it is one transaction.
Well if anyone is going to suggest that to open, process close, commit ....well i tried that but it also gives error "nmo free buffer pool" but this comes for twice the size of buffer size = 100 Mb file when db cache size is 50 mb.
any ideas.Hello,
Ia using Oracle 9.0.1.3.1
I am getting error ORA-OO379 No free Buffers available in Buffer Pool. Default for block size 8k.
My Init.ora file is
# Copyright (c) 1991, 2001 by Oracle Corporation
# Cache and I/O
db_block_size=8192
db_cache_size=104857600
# Cursors and Library Cache
open_cursors=300
# Diagnostics and Statistics
background_dump_dest=C:\oracle\admin\iasdb\bdump
core_dump_dest=C:\oracle\admin\iasdb\cdump
timed_statistics=TRUE
user_dump_dest=C:\oracle\admin\iasdb\udump
# Distributed, Replication and Snapshot
db_domain="removed"
remote_login_passwordfile=EXCLUSIVE
# File Configuration
control_files=("C:\oracle\oradata\iasdb\CONTROL01.CTL", "C:\oracle\oradata\iasdb\CONTROL02.CTL", "C:\oracle\oradata\iasdb\CONTROL03.CTL")
# Job Queues
job_queue_processes=4
# MTS
dispatchers="(PROTOCOL=TCP)(PRE=oracle.aurora.server.GiopServer)", "(PROTOCOL=TCP)(PRE=oracle.aurora.server.SGiopServer)"
# Miscellaneous
aq_tm_processes=1
compatible=9.0.0
db_name=iasdb
# Network Registration
instance_name=iasdb
# Pools
java_pool_size=41943040
shared_pool_size=33554432
# Processes and Sessions
processes=150
# Redo Log and Recovery
fast_start_mttr_target=300
# Sort, Hash Joins, Bitmap Indexes
pga_aggregate_target=33554432
sort_area_size=524288
# System Managed Undo and Rollback Segments
undo_management=AUTO
undo_tablespace=UNDOTBS -
Data Buffer Quality got down below 90%
Hi,
The data buffer quality in ST04 getting reduced gradually and came down below 90%, there are 8 app servers on our production, how to improve the data buffer quality, please suggest.
Thanks,
PavanHi Pavan,
r u running update optimizer stats daily
please check below links its helpfull to u
http://sap.ittoolbox.com/groups/technical-functional/sap-basis/st04-database-performance-analysis-shared-pool-and-data-buffers-770596?cv=expanded
http://www.uber-goober.com/~ubergoob/forums/showthread.php?t=105003
Regards,
Srinu -
Have somebody used it and what are your comments?
I have very high activity for specific tables growing over 15-20 mnl of records. Many inserts and few select. very optimized SQL but still slower then the same code on DB2.
I would like to separate may be temp tablespace, and a few tables I never select from - like log and audit tables.
Will multiple Buffer Pools be beneficiary for me?
Thanks,Thanks a lot - Yes, your assumption is absolutely right - the application always reports much higher time then I could see from the Oracle side even when I add all SQLNet waits. The same time on Db2 is approximatelly equal - again, the app reported time is a little bit higher, but it's not 250 times difference like in Oracle.
The app is 3rd party and get a lot of data in and out. The app structure is: Reading XML file and inserting the values in common tables like Address, Name, etc. As a next step the application will check if these records already exist and will perform specific logic if previous entries are found. From Oracle point these are multiple selects and few possible updates and/or inserts. After all processing is done a record in a log table will be inserted and the transaction is commited. Then the app gets the next XML record. This is single threaded process repeating over and over again. The capacity is about 25,000 records inserted per minute with about 40 application instances running simultaneously. if I increase the number of app instances running against DB2 to 100, the insert rate jumps to 60-65,000/min. In Oracle is the opposite - the increase of the app processes more then 45-50 do not change the insert rate at all. Even on SQL server I can run about 70 processes... So, something is wrong with the way Oracle process runs. These results are not new and have been run on at least 30 different hardware setups for months -AIX, linux, Solaris, windows, and on differnet type of hardware. This is the result for all of them. Everybody who tried the app reports the same case. Most of this cases though do not have well tuned environment... That's why I'm trying to make it work better - could not be "just doesn't run!!!" - Oracle is a great scalable system!
I've already thought to run the app locally on the server, but it's very hard as the usual set up takes about 3-4 hours and the app is very CPU consuming. But for a single app instance it'll work.
I think your idea is great and I must do it. Let me do that first thing on Monday and I'll post the results.
Thanks a lot,
mj -
Need help in clearing string buffer during dynamic VO where clause in oaf
Hi All,
I am dynamically setting where clause in OAF using string buffer, but the issue is when i am executing the vo multiple times so the old data in the string buffer it is not clearing .so every time my where clause adding to the query and it is erroring out, please help me how to clear string buffer class in oaf.
ThnaksHi,
Could you please share the code segment for reference. Then we can tell the solution.
Regards,
Tarun -
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...
Markusthis 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 -
AWR Report -- Buffer Pool Advisory
Hi,
does anyone know in that kind of measurement the "Estimated Phys Reads (thousands)" from buffer pool advisory is ?
I mean in seconds ? in hours ? addicted to the time period the report was written ?
http://img.ly/images/6379055/full
Thanks a lot
*TRe,
OK it makes it a little bit clearer.
What I now think to understand is that the "Estimated Phys Reads (thousands) no represents the
current workload of the system it only gives clue that there will be a change around 3 times more blocks was red.
Right ?
But if it is like that why these numbers are changing from one to another report....
So again another image.... Maybe my problem is that I try to set the current workload (phys block reads) in comparison with the "Estimated Phy Reads from the Advisory....
Our AWR reports are generated every hour.
http://img.ly/qNfn
Sorry for my understanding problem... I also will try to check if the views gave other information than the ARW report.
*T -
Can not find Flush Return Data Buffer.vi
When I try to start my Labview program I get a "Error -70025 occurred at Read Home Input Status.vi" because the Return Data Buffer is not empty.
I searched for the Flush Return Data Buffer.vi in the Labview library but it is not there.
Where can I find it?Hello Mishka,
The Flush Return Data Buffer.vi should be located in your functions palette at Vision and Motion>>73xx>>Advanced>>Flush RDB.vi. Alternatively, you can press ctrl+space on your keyboard to open the quick drop menu and then search for Flush RDB.vi.
Regards,
J_Bou -
How to get the data from Pooled Table T157E.
Hi Experts,
How to get the data from Pooled Table T157E.
Any help.
Thanks in Advance,
Ur's Harsha.create some internal table similar to T157E and pass all data as per SPRAS.
After that use internal table in your program as per the requirement.
Regds,
Anil -
Posting date and clearing date different in G/L clearing document
Hi Friends,
While clearing a G/L manually using F-03, the clearing date is entered in the selection screen.
The clearing document which is posted is posted with the posting date same as the clearing date mentioned in the selection screen of F-03.
In what situations can the posting date of a G/l clearing document be different from the clearing date?
Regards,
ShilpiHi,
The Clearing Date in F-03 is actually the Posting date, so in this case the posting date will be same as clearing date. But a clearing document can also be created when you reverse a FI document, in this case the Reversal document will have a clearing date different than posting date. Let me know if this info helps you -
How to clear data in Table Control.
hi! all
How to clear the data in table control.
i have a Table control which displays column A data from the previous screen and allows to enter column B and column C and i have a button CLEAR, when i click CLEAR button the Data displaying in table control has to be cleared. how to do it.
Regards,
NagulanHi,
Loop over the internal table of table control & clear data from table control.
loop at tctab.
clear tctab.
modify tctab.
endloop.
Best regards,
Prashant
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