I/O Performance And Out Of Memory?
Jun 12, 2013
we are using windows server 2008 R2 and oracle database version 11.2.0.2
Have two points here : I/O performance and Out of memory issue
1.) ADDM Report recommended solution is to stripe all data files for to reduce "Wait class "User I/O" was consuming" But I am not sure It will improve more I/O performance(it will resolved the issue) and same issue we are getting on many servers.
ADDM Report Snipped:
Findings and Recommendations
----------------------------
Finding 1: I/O Throughput
Impact is .28 active sessions, 44.97% of total activity.
--------------------------------------------------------
The throughput of the I/O subsystem was significantly lower than expected.
Recommendation 1: Host Configuration
Estimated benefit is .28 active sessions, 44.97% of total activity.
[code]....
2.) Same issue we got in another server and we increased memory thrice but again we got same below error. Now we are getting same below error another server.
Alert log Snipped:=
Wed Jun 12 07:12:15 2013
Process startup failed, error stack:
Errors in file E:\APP\ORACLE\diag\rdbms\oemgc\oemgc\trace\oemgc_psp0_3316.trc:
ORA-27300: OS system dependent operation:CreateThread failed with status: 8
ORA-27301: OS failure message: Not enough storage is available to process this command.
ORA-27302: failure occurred at: ssthrddcr
[code]....
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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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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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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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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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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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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 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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Jul 25, 2012
I have the following setup
SQL> show parameter sga;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE
pre_page_sga boolean FALSE
sga_max_size big integer 3G
sga_target big integer 2G
from what I read I beleive this will initially grab 2GB of memory on startup and will grab up to to 3GB of memory total for the SGA. The "total" memory can be allocated to different peices of the SGA when needed but will never exceed 3GB. Is this correct or would these settings infringe on any available memory on a system that is already tight on memory?
Secondly, what happens if both these values are set to the same value?
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May 23, 2013
Can i know the internal process of initialization of DB into memory in timesten , when a new connection is establishing? Will timesten create tables and indexes in RAM when first connection is established if the RAM policy is default?
want to know the internal functional flow of timesten when any command is fired against it.
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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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Sep 30, 2010
How the length of column width effects index performance?
For example if i had IOT table emp_iot with columns:
(id number,
job varchar2(20),
time date,
plan number)
Table key consist of(id, job, time)
Column JOB has fixed list of distinct values ('ANALYST', 'NIGHT_WORKED', etc...).
What performance increase i could expect if in column "job" i would store not names but concrete numbers identifying job names.
For e.g. i would store "1" instead 'ANALYST' and "2" instead 'NIGHT_WORKED'.
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Jun 16, 2010
I have a question about database fragmentation.I know that fragmentation can reduce performance in query times. The blocks are distributed in many extents and scans process takes a long time. Oracle engine have to locate the address of the next extent..
I want to know if there is any system view in which you can check if your table or index has high fragmentation. If it's needed I will have to re-create, move or rebulid the table or index, but before I want to know if the degree of fragmentation is high.
Any useful script or query to do this, any interesting oracle system view?
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Jun 16, 2011
How many records could I have in a single table without performance degradation with Standard Edition without partitioning with cutting-edge server (8 or 12 cores, 72 GB RAM, FC 4 Gbit, etc...) and good storage?
300 Millions in only one table with 500K transactions / day is too much?
Simple database with simple schema.
How many records begin to be too many?
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Nov 15, 2010
Testing our 9i to 11g upgrade, we've imported the entire DB into the new machine.We've found that certain procedures are really suffering performance problems. BUT, we've also found, that if we check out a production copy of the procedure from our source code control, and reinstall it, the performance issue goes away. Just alter the procedure and recompiling does NOT work.
The new machine where the 11g database exists is slightly different than the source, but it's not like we have this problem with every procedure. It's only a couple.
any possible reason that we'd have to re-install a procedure to correct a performance problem?
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Apr 12, 2013
I need to check the package performance and need to improve the package performance.
1. how to check the package performance(each and every statement in the package)?
2. In the package using the delete statement to delete all records and observed that delete is taking long time to delete all the records in the table(Table records 7000000). This table is like staging table.Daily need to clean the data before inserting the data into it. what can I use instead of Delete.
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Aug 9, 2010
Somewhere I read that we should not use hints in Oracle production environments, but we can use hints in the development environment and on achieving the desired execution plan we can adjust the 'statistics' to follow that plan without hints.
Q1. If it is true what statistics do we adjust for influencing the execution plan and how?
For example, I have the following simple query:
select e.empid, e.ename, d.dname
from emp e, dept d
where e.deptno=d.deptno;
emp.empid, emp.deptno and dep.deptno columns have indexes and the tables have the standard structure as found in the basic oracle examples.
If I look at the execution plan of the above query then I see that the driving table is empand the driven table is dept.Also the type of join that is taking place is 'Nested Loop'.
Questions: With respect to the above query,
Q 2. If I want to make dept the driving table and emp the driven table then how can I adjust the statistics to achieve that?
Q 3. If I want to use hash join instead of a nested loop join then then how can I adjust the statistics to achieve that?
I can put the ordered and the use_hash hint to effect this but again I have heard that altering statistics is a more robust way to control an execution plan as compared to hints.
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Dec 6, 2011
I have an issue with export(expdp).
When i exporting an user using expdp utility, the load the on the server is going up-to 5. The size of the database is 180GB. Below is the command that i use for export.
expdp sys/xxxx directory=dbpdump dumpfile=expdp_trk_backup.dmp logfile=expdp_trk_backup.log exclude=statistics schemas=trk
Do i need any look into any memory parameters for this?
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Nov 16, 2012
I am not a major member of performance tuning area.Performance team is saying DB utilizing high memory. DB team is telling DB utilizing low memory.
How it was calculated here ?
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Mar 18, 2013
Currently weblogic has 120 concurrent connections to the database.There is a requirement to scale up the number ofconcurrent connections to 300.We have did some study and quite be quite sure that the current sga and pga is required. (the additional connections will be firing the same sql which is very well tuned.
However each additional connection to the database will take up additional memory just for the connection?Will is be using the memory in the PGA? Or outside the PGA for the connection overhead?We are not using MTS.
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Feb 5, 2013
1)collections uses pga memory ,does globle tem table used in sp also uses PGA memory.
2)and does type of table of object type uses pga memory.
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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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Nov 12, 2012
I have a 11.2.0.3 database runing on AIX. The instance hangs and crashes due to memory usage issues. I checked the alert log of the database and this is what i see:
WARNING: Heavy swapping observed on system in last 5 mins.pct of memory swapped in [11.85%] pct of memory swapped out [3.45%]. make sure there is no memory pressure and the SGA and PGA are configured correctly. Look at DBRM trace file for more details.i also see the following in the alert.log:
Errors in file
/opt/oracle/diag/rdbms/iut3px1/iut3px1/trace/iut3px1_cjq0_55312404.trc:
ORA-00604: error occurred at recursive SQL level 2
ORA-04031: unable to allocate 3896 bytes of shared memory ("shared pool","select audit$,options from p...","sga heap(1,0)","kglsim object batch")
The file contents of iut3px1_cjq0_55312404.trc are:
====================
Process State Object
====================
----------------------------------------
SO: 0x70000007b97de70, type: 2, owner: 0x0, flag: INIT/-/-/0x00 if: 0x3 c: 0x3
proc=0x70000007b97de70, name=process, file=ksu.h LINE:12616 ID:, pg=0
[code]...
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Feb 28, 2012
I am facing this error in my application page
OraOLEDB(0x80040E14)
ROW-00001
Cannot allocate memory
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Nov 27, 2012
I have a quick question about Automatic Memory Management in 11g. I know that it combines the SGA and PGA components together, but the pga_aggregate_target (in 10g) was a target, rather than a strict limit. In certain circumstances you could (and we have) exceed the pga_ aggregate_ target by quite some way.
If I use AMM, does this enforce a limit on the PGA usage – or if I through enough bind variables at it, can I still exceed the ‘target’?
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Oct 10, 2012
Specs are as follows:
Linux kernel 2.6.18-274.12.1.el5
Total physical memory - 96G
Oracle version:
Oracle Database 11g Release 11.1.0.6.0 - 64bit Production (Standard Edition)
I am having trouble making my spfile parameters take effect and would like to set them manually. Disk reads are very slow, so I thought I would look at the db_cache_size in the spfile:
<INSTANCE>.__db_cache_size=805306368
But, when I look at the parameter via 'show parameter cache':
db_cache_size big integer 0
Digging deeper, I noticed none of my <INSTANCE>.__ parameters match the values returned from 'show parameter'. Most of my concern is sga_target & pga_aggregate_target both being zero.
My memory targets:
memory_max_target big integer 49G
memory_target big integer 49G
I would like to increase the db_cache_size in an attempt to reduce the table scan time.
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May 13, 2013
When investigating memory usage on HP-UX V3 for my oracle database 11.2.0.3.4 which use AMM, it seems to me that system is not shifting shared SGA memory to private PGA memory when needed but it allocate other memory.The shared memory don't shrink all the memory_target id allocated. VSZ = RSZ
To test i have used this script which will allocate memory in process PGA.
create or replace package demo_pkg
as
type array is table of char(2000) index by binary_integer;
g_data array;
end;
[code]...
I have done the same test on a linux machine (Red Hat Enterprise Linux Server release 6.3) and the size of the POSIX shared memory switched (/dev/shm) to the PGA like demonstrated by Tanel Poder in his blog [URL]...
Related conf :
lock_sga=FALSE
pre_page_sga=FALSE
pga_aggregate_target 0
sga_target 0
memory_target 5553258496
memory_max_target 5553258496
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