Performance Tuning :: Memory And SGA Target In Oracle 11gR2?
Dec 29, 2012
I am aware that from 11g, memory_target is sufficient for memeory management between SGA and PGA.
what happens if MEMORY_TARGET set to non-zero and SGA_TARGET set to zero values in a 11g database? Does it enable automatic memory management within the SGA?
We regularly hit by ORA-4031 errors. Also, memory_target advisory (v$memory_target_advice) does not show any advisory information.
for eg:
memory_max_target = 500m
memory_target = 500m
and
sga_max_size=500m
sga_target=0
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Jan 15, 2011
I have a confusion with MEMORY_TARGET and MEMORY_MAX_TARGET parameter. if i set SGA_TARGET, SGA_MAX_SIZE along with MEMORY_TARGET and MEMORY_MAX_TARGET then how oracle will manage the memory? Because as per my understanding if we set MEM
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Oct 16, 2012
I am building a database to store call quality statistics for VOIP networks. It is a very insert heavy application, and data reliability is of relatively minimal importance (in the sense that a few corrupt call records here and there doesn't matter the way corruption does in for example a banks database). Long term storage is also unimportant, most customers only wish to keep 3 months of data readily available in the database. Most do not even archive the older data.
To that end I am searching for every possible way to improve my insert performance and the internet has turned me onto the idea of NOLOGGING. These are the steps I have taken to reduce my IO consumed by the Redo and Undo logs.
1. I am inserting with the APPEND_VALUES hint.
2. I have disabled force logging at the database level
3. I have disabled force logging at the tablespace level
4. I have disabled logging on the relevant table and each of its indices
As best I can tell this is all I can do to minimize Redo/Undo, but based on my observations of the Disk portion of the WinServer2008 Performance Monitor, this has made little to no change in the amount of IO to my REDO and UNDO files. IO to the .dbf containing my table makes up less than 20% of the total disk IO for oracle.exe, the rest is the REDO and UNDO logs.
asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:897564200346274711
The above article is a little over my head but I am able to extract from it that I will never entirely eliminate REDO/UNDO, which is fine, but I would think I could get it lower than it currently is.ted.
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Nov 18, 2012
I have a question regarding memory parameters in oracle database 9.2.0.8, especially sga_max_size and db_cache_size. Database server has 32G of ram. Oracle parameter on server shmmax is set to 16G. Is reasonable to set sga_max_size to the same value, and db_cache_size to 80% of that size?
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Jul 31, 2012
We are using the 11g AMM feature and Memory_Target set to 96GB and total RAM on the Server is 128GB Now the top and free shows up only 200MB memory free on the system.
There are 2 process dbw0 and dbw1 which consumes the top memory and this is 30GB per dbw.
Why is the dbw process taking up so much memory when there is not much load on the database.
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Jun 20, 2012
we have 96GB Memory on the UNIX server and 85% of its usage shows oracle processes I want to determine which Oracle processes are taking most of the memory
SGA is around 36G
SGA_TARGET is 40G
PGA is around 4G
the total of around 40-45 GB of usage is understandable but what other oracle process are chewing up the remaining 30-40 GB on the server is not known
load averages: 7.35, 6.46, 6.15; up 248+11:33:21 12:25:03
2202 processes: 2196 sleeping, 1 zombie, 5 on cpu
CPU states: 83.8% idle, 10.5% user, 5.8% kernel, 0.0% iowait, 0.0% swap
Memory: 96G phys mem, 15G free mem, 128G total swap, 128G free swap
PID USERNAME LWP PRI NICE SIZE RES STATE TIME CPU COMMAND
21720 oracle 258 0 0 40G 40G cpu/48 215:28 2.04% oracle
10709 oracle 1 0 2 1816K 1448K cpu/9 0:02 0.90% res_conf_email_
[code]......
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Dec 24, 2012
The below query is taking high CPU almost 98% and longer time to execute.
SELECT ancestor,
Max(D.alarmstate) ALARMSTATE,
Max(D.sialarmstate) SIALARMSTATE,
Max(D.uncralarmstate) UNCRALARMSTATE,
Max(M.commstate) COMMSTATE,
Max(M.nncommstate) NNCOMMSTATE,
Max(M.servicestate) SERVICESTATE,
Max(M.abnormal) ABNORMAL,
CASE
[code]....
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Aug 25, 2011
If I have specify the SGA_TARGET, do I still need to specify the amount of memory for SHARED_POOL_SIZE? I thought once the SGA_TARGET, auto memory management is in place and SHARED_POOL is not neccessary.
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Aug 24, 2012
We are using the 11.1.0.7 database, we implemented the Memory_Max_Target and Memory_target in the database.Here is the value of the memory parameters:
SQL> show parameter memory_
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
hi_shared_memory_address integer 0
memory_max_target big integer 3G
memory_target big integer 2G
shared_memory_address integer 0
We want to increase the value of the Memory_target=3G, means, I want to increase the value of the memory_target upto Memory_max_target by using below command:alter system set MEMORY_TARGET=3G scope=both SID='OLTP1'; but I am getting below error:
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-00846: could not shrink MEMORY_TARGET to specified value
I tried to give the memory_target value less than the memory_max_target value like:alter system set MEMORY_TARGET=2900M scope=both SID='OLTP1'; but get the same error:
ERROR at line 1:
ORA-02097: parameter cannot be modified because specified value is invalid
ORA-00846: could not shrink MEMORY_TARGET to specified value
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Jun 10, 2013
I am using 11g version, and trying to understand the Memory Allocation.
1) The new feature Memory target parameters are dynamic? is in it? But when I set with the ALTER SYSTEM... it was not changed, then I had to restart the DB.
2) With the new 2 parameters (MEMORY_MAX_TARGET, MEMORY_TARGET), the SGA_MAX_SIZE parameter should be 0, right? But in my case, the SGA_MAX_SIZE value is automatically assigned.
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Jul 24, 2013
determine if a function is worth pinning in memory? I want to come up with a percentage, implying that if the function is already im memory 80%+ of the time then it is not worth it.
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Feb 13, 2013
I have two tables with same columns(15 of them), I am trying to find difference between two tables using minus operator and then insert in stage table using below code
Issue is table1 has 50 million records
table2 is empty
so when first time when we execute this v_collection1,v_collection2 collection will have 50 million records in it which will go in memory, I think this is not good, because going in memory will eat memory and resources while sorting and other activities ?
After fetching records in collection we are inserting that in stage table and then COMMIT so i think that wont be good because committing 50 million will generate large amount of redo?
below is snippet of my code
DECLARE
type lst_collection1
IS
TABLE OF table1.col1%type INDEX BY binary_integer;
type lst_collection2
IS
[code].......
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Aug 31, 2011
I am trying to run a trace file with TKPROF. It throws an error :
MEMORY FAULT
The size of the trace file is 8MB. I tried with some other file trace files bigger in size (10MB) than the above file, it works fine. I tried seeing any permission right is required on that trace file is required for the tkprof to excute, but it has got the same permissions like the other trace files.
The problem is that it is not showing any error number or any other Error Description other than "MEMORY FAULT".
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Feb 11, 2011
I have few queries on PGA memory management.Since these queries are based on 2-3 examples not exactly same by nature I am summarising it after my understanding for the same
As I understand many workareas can be allocated to a single sql statement and number and sizes of theses workareas is controlled internally by Oracle when Automatic Memory management (PGA_aggregate_target and workarea_size_policy=Auto are set) Since many sessions share the PGA memory, the amount of memory available to each session may vary and if less amount of memory is available for a session for sorting then TEMP tablespace is used
[1] Can we say paging happens and can be checked at this time?
[2] Is there a difference in handling memory while populating pl/sql tables?
As I have encountered ora-04030 while some our developers were populating pl/sql tables but never encountered this error for sorting, hash joins etc Though I don't remember the width of pl/sql table, I am sure the developer used 'LIMIT' clause during bulk collect and still faced the issue.
With a single session on the server, I noticed that the difference in values displayed issuing 'free' command in linux and output values from sesstat did not match at all while there wasn't any heavy OS process involved during the period. I was expecting 'used' and 'free' values displayed by free command (linux) will change and difference would be approximately equals 'before and after values of session pga memory.
[3] Isn't it expected to match?
[4] Can we say in dedicated server, at any moment of time, the SUM of 'session pga memory' represents all the memory used by Oracle SGA, at that point of time?
select sum(value)/1024/1024 "memory in MB" from v$sesstat where statistic#=20;
During one of the tests I got following output (divide value by 10 for my visibility and avoid formatting)
SQL> select a.name, to_char(b.value/10, '999,999,999') value
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
and a.name like '%ga memory%'; 2 3 4
[code]...
The above query is showing above values even when the pl/sql block execution is completed 30 minutes back
[5] Do we call this as 'memory leak' where memory is not released even while some time has passed since session has done something?Of course I am not checking at OS level as mentioned in question [3] above the values won't match!
Still the output of free command for reference(After the pl/sql block executed)
SQL> !free
total used free shared buffers cached
Mem: 3016796 2999660 17136 0 4308 1173260
-/+ buffers/cache: 1822092 1194704
Swap: 1048568 636124 412444
--(After the pl/sql block executed)
SQL> select * from v$pgastat;
NAMEVALUEUNIT
aggregate PGA target parameter 524288000bytes
aggregate PGA auto target 456256512bytes
global memory bound 26214400bytes
total PGA inuse 17328128bytes
[code]...
[6] What could be the significance of negative values of 'session pga memory/max'?
Last We have an OLTP system and in the night we run batch processes in 2-4 sessions
Suppose I have 10 GB RAM and with PGA setting of 3.5 GB Now I want the batch process sessions to use max possible memory during nighttime and toggle the setting back in the morning
[7] With above settings (10 GB RAM and 3.5 GB PGA) how can I divide the memory among 4 sessions?
Shall I set 1) PGA_aggregate_target=0 2)Workarea_size_policy=manual 3) Sort_are_size 4) Hash_area_size
[8] What would be approx values for parameter 3 and 4? will it be straight 3.5 GB/ 4?
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Jul 5, 2012
i am running 11.2.0.1 on HP-UX PA-RISC (64-bit). My Memory max target is defined as 34 GB and memory target is 32 GB on the database. The host has 256 GB physical memory. i see memory utlization is almost 90% used when seen from Grid Control on the host and wondering, what's going on? when i see into more details, i see the following 3 HP Processes consuming around 3.6 GB memory and rest very small is consumed by Oracle processes. Who's using the rest of the memory?
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Aug 5, 2013
SQL> select name,decode(unit,'bytes',value/1024/1024,value) as mb from v$pgastat; NAME MB---------------------------------------------------------------- ----------aggregate PGA target parameter 25600aggregate PGA auto target 2724.14648global memory bound 1024total PGA inuse 22601.7333total PGA allocated 26653.6230maximum PGA allocated
[code]....
I understand I have soft limit( aggregate PGA target parameter) which was overlimited (maximum PGA allocated = 35374.4638) hence we have over allocation count>0.Extra bytes read/written=13GB,hence we have excessive 13Gb that we had to flush on disk(excessive I/O operations) cause of limitation in 1024MB(global memory bound)(it's not enough to join or to sort something so we must do onepassor multipass) ,which defines the size of single operation of sort or join(so does it mean that it's some kind of sort_area_size and hash_area_size for automatic workarea_size_policy? and in this case what about _smm_max_size?)aggregate PGA auto target - is the amount of space(total) that Oracle can give for work areas running in automatic mode.
So I can't understand ratio between global memory bound and aggregate PGA auto target - why does the aggregate PGA auto target such tiny?(relatively process count)?Is the global memory bound static for particular aggregate PGA target parameter?
I can change it only by redefining aggregate PGA target parameter?What would be with aggregate PGA auto target if I started 10 sort operation and each of them takes about 1Gb of memory.How huge it would be? 10Gb?
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May 25, 2013
I am using 11gR2 on windows server. This is the query that runs many times a day and effect badly the performance of database. I don't have much idea about this query.
SELECT TO_CHAR(current_timestamp AT TIME ZONE 'GMT', 'YYYY-MM-DD HH24:MI:SS TZD') AS curr_timestamp, COUNT(username) AS failed_count
FROM sys.dba_audit_session
WHERE returncode != 0 AND TO_CHAR(timestamp, 'YYYY-MM-DD HH24:MI:SS') >= TO_CHAR(current_timestamp - TO_DSINTERVAL('0 0:30:00'), 'YYYY-MM-DD HH24:MI:SS')
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Feb 9, 2012
We are having major differences in performance when accessing an Oracle 11gR2 database from two different environments.
I won't sadden you with the gory details of the full application but I will use an indicative example of our problem.
We have SQL Developer in both environments. In each of these SQL Developer instances is a defined a connection to the same database on another machine. So there is the PC looking at a database and a virtual instance looking at the same database.
Selecting the '+' sign next to 'tables' for that connection, on the PC the list of four tables comes back in 4 seconds but on the virtual instance the list of the same four tables comes back in 1 minute and 50 seconds.
This sort of timing issue is repeatable for all accesses to the Oracle database on the third machine.
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Jul 12, 2013
I have installed database in one server. I would like to enable AWR into it. Statistics_level is set to Typical. While running the below script to enable the AWR, its gives error -
SQL> exec dbms_scheduler.enable('GATHER_STATS_JOBS');
BEGIN dbms_scheduler.enable('GATHER_STATS_JOBS'); END;
*
ERROR at line 1:
ORA-27476: "SYS.GATHER_STATS_JOBS" does not exist
ORA-06512: at "SYS.DBMS_ISCHED", line 4343
ORA-06512: at "SYS.DBMS_SCHEDULER", line 2802
ORA-06512: at line 1
make AWR automatical generation.
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Aug 28, 2012
I am running an Oracle 10.2.0.3 on Solaris 5.9 OS. Front end appplication is PeopleSoft v8.8.From my AWR report I have found below SQL which needs to be tuned:
SELECT TO_CHAR (TO_DATE (TO_CHAR (B.ASOFDATE, 'YYYY-MM-DD'), 'yyyy-mm-dd'),
'dd/mm/yyyy'),
B.EMPLID,
B.PWCUK_LEGACY_ID,
B.NAME,
[code]...
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Jul 12, 2010
Looking to understand the difference between instance tuning and database tuning.
What is the difference between these two tuning exercises? I understand that an instance is memory based structures (logical) where as database consists of physical structures.
However, how does one tune a database the physical structure? Does it have to do with file placements/block sizes etc. Would you agree that a lot of that is taken care by ASM now in 11g? What tools are required/available (third party as well as oracle supplied) for these types of tuning scenarios?
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Nov 13, 2010
Recently i have been working analyzing Oracle Row Chaining and Migration in the database. Is their any way to track the chaining & migration of rows as part of database health checkup.
Else we have analyze the table for detecting row Chaining and Migration.
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Oct 31, 2013
We are re-designing our App and we have a critical question, what's the best way (in terms of performance) of using TIFF images (about 20K size) with Oracle.
Currently we have a Windows shared file server and we create the tiff images there under a huge directory structure (like /images/ddddmmyy/aa/bb/001, then /images/ddddmmyy/aa/bb/002, etc, etc). Our database is usually in LINUX version 10, 11 or 12. We create about 200,000 images per day, keep them for 60 days and then remove that structure.
Our Web app (developed with .NET) reads those images just to display them on a Web Session (IE).As you can see, what we are doing now works fine. But network sometimes is an issue and also it's hard to keep synchronization with our DR server, backups, etc.
Are we taking the correct approach? It would be better to have the images in CLOB or BLOBS for better performance? If so, As I mentioned, performance is the KEY FACTOR and the most important item to consider in this design.
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Oct 25, 2010
I am querying a table having 6 million records,It takes arround 35 seconds in command line terminal using putty in a windows client.
Also the server is linux centos with oracle 11g installed. I saw the method Oracle result_cache which i am suspecting to be fast
my query is
"select /*+ result_cache */ * from relationshipobject;"
SQL> set autotrace traceonly stat
SQL> set timi on
[Code]....
i can i reduce my query execution time and consistent gets?
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Mar 24, 2013
how do you limit oracle redo?
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Dec 2, 2010
I have a table "NEWS_COMMENT" like this:
Name Type
------- --------------
ID NUMBER(8)
USERID NUMBER(8)
SORT_TEXT VARCHAR2(100)
TEXT VARCHAR2(1000)
DATE DATE
VALID VARCHAR2(1)
CODNEW NUMBER(10)
The table has a normal index for the userid column.
There is a query that looks for the differents CODNEW for a USERID but allways the CODNEW has to be greater than 2248833
select codnew from news-comment where userid=2914655 and valid='N' and codnew>2248833
I have created a new index for this kind of querys
create index coment_new_IDX on news_comment
(CASE WHEN codnew >2248833 and valid='N' THEN userid ELSE NULL END )
but oracle doesn't use it. I have used a hint to force it but doesn't run.
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Jun 7, 2011
We have a data migration scripts written for oracle. Data is not huge but we are observing that the migration is faster in the development labs but is 5x slower in the production site.
The development Oracle setup is on Windows and Production setup on Solaris. I have attached the AWR generated for a period where migration was run for 3 hours and stopped due to slow performance.
Here is my initial analysis.
1) The first timed events is the DB CPU. Hence I feel the migration scripts can be modified to run in parallel so that they can finish faster. However here the question arises why it should run faster in development env if this is an issue.
2) I tried increasing the
a.large_pool_size set to 512M
b.sga_max_size set to 8G
c.sga_target set to 8G
from 0, 4G and 4G respectively.
I have attached the AWR and below are the etc/system contents for solaris settings.
* Begin MDD root info (do not edit)
rootdev:/pseudo/md@0:0,1,blk
* End MDD root info (do not edit)
set noexec_user_stack=1
set noexec_user_stack_log=1
* IBMdpo vpath_START (do not remove)
* default SCSI timeout is 60 seconds
* uncomment to change SCSI timeout * set sd:sd_io_time=0x1e
forceload: drv/vpathdd
* IBMdpo vpath_END (do not remove)
set noexec_user_stack=1
set semsys:seminfo_semmni=100
set semsys:seminfo_semmns=1024
set semsys:seminfo_semmsl=256
set semsys:seminfo_semvmx=32767
set shmsys:shminfo_shmmax=4294967295
set shmsys:shminfo_shmmin=1
set shmsys:shminfo_shmmni=100
set shmsys:shminfo_shmseg=10
P.S. The awr report is renamed to .txt from .html to be able to upload the file.
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Apr 7, 2011
Here, let me explain:
I have create a table with 8 million records and 2 different indexes using 2 different columns (columns name NUM1 & NUM2) on that table. First indexed column (NUM1) values have many different values (1,2,3... etc).
Second indexed column (NUM2) values have only 2 different values.
7999999 records values is same("A") and remaining one record values is different("B").
Query1:
select * from tbl where num1=val
Query2:
select * from tbl where num2='B'
I have compare explain plan both queries, but Query2 doesn't use predefined index. Why Oracle don't use my redefined index at column NUM2?
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Sep 9, 2010
Oracle UNION ALL performance issue: when I try to run below SQL query separately SQL part1 and SQL part2 it takes some seconds only but if I run together with group by and without group by it take much time.
SELECT AVG(date_completed-login_date),to_char(to_date(login_date), 'YYYY') as wYear FROM
(
SELECT test.date_completed 'date_completed',sample.login_date 'login_date')
FROM sample test
where (some conditions) ) ---SQL part 1
UNION ALL
[code]...
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Feb 21, 2013
I have a query optimized as to it indexes and others runs immediately when the answer is few records in SQL Server such as Oracle, however when the result is large eg 20,000 records all data access times are very diferent. The query returns many fields (about 20) and some of them are of type Varchar 250 and some of 2000 I understand here may be the problem, but not is because for similar results (20,000 records) sql run in 2 seconds and Oracle but it responds little to have full data takes around 30 seconds. The problem is really in bringing information to all these fields since if the inquiry it also but only returning a numeric field is done in 2 seconds. Tests I've done them both through ODBC, in the Toad as in the own Oracle console on the server, so it is not problem Driver or flow of data through the network, I would like to think that this is some of the settings I think there is as much difference between Oracle and Sql. The databases are ORACLE 10 and SQL Server 2008.
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