Performance Tuning :: Create Statements On A Highly Fragmented Disk
Nov 24, 2010
On Oracle 10g, I create, delete and drop a lot of tables. Therefore, the disk is highly fragmented.The execution of a very simple create statement takes more than a minute. If I execute the same statement but first truncate the table and insert the data, it takes less than a second!
I think this has to do with the high fragmentation of the disk. Obviously, I can defragment the disk, but I will always have a high fragmentation since I use a lot of create, delete and drops.
how I can improve the performance of create statements on highly fragmented disks?
We are working on a Data warehouse (ard 50G ) architecture with the following acquired environment:
Single server X3650 M4 Dual CPU ( 16 core in total ) with 48G ram Oracle standard 10g x64 Windows 2008 x64 128 SSD x 8 IBM ServeRAID M5110e SAS/SATA Controller
Due to budget concern, we will be running the App server(Business OBjects 4.0 w/ Tomcat and DB server on the same machine. ) We have a user base of around 30 ppl on the app server.
We intend to have external redundancy using IBM raid card on raid 10 configuration. I wonder what kind of disk config yield better performance if we only have write update in the morning and 95% read for the rest ?
Raid 1 for OS (128SSD x 2 including DB logfile ) Raid 10 for DB server ( 128 SSD x 6 )
I heard ASM provides better disk management but just wonder it increase performance in anyway.
I have 2 servers both having windows server 2008 64 bit as operating system installed on both I need to install oracle clusterware 11g r1 on both servers with clustering on external storage. I have configured the network(private,public and virtual) for both servers and have started the installation.
In the installation of oracle I add both servers but then I reach to a point where they ask me for voting disk or ocr disk in the cluster configuration storage but no disk is present how can i create ocr disk or voting disk on windows server 2008? And the external storage should I buy a special type of storage that supports clustering to continue my work?
* 35 | ID TABLE ACCESS BY INDEX ROW | S_ORG_EXT | 3064K| 2472M| | 1 (0)| 00:00:01 | | 36 | INDEX FULL SCAN | S_ORG_EXT_U1 | 14 | | | 1 (0)| 00:00:01 |
Predicate Information (identified by operation id): --------------------------------------------------- 35 - filter("T2"."ACCNT_FLG"<>'N' AND ("T2"."INT_ORG_FLG"<>'Y' OR "T2"."PRTNR_FLG"<>'N'))
This unselective index scan on step 36 of the explain is returning 14 rows but optimizer is selecting 3064 K rows from the table .
I tried creating combined index on all 3 columns mentioned in the predicates for 35th step , but that is not utilized .
how to index this whole expression ::--
(ACCNT_FLG<>'N' AND (INT_ORG_FLG<>'Y' OR PRTNR_FLG<>'N'))
Something like CREATE INDEX XYZ on table((ACCNT_FLG<>'N' AND (INT_ORG_FLG<>'Y' OR PRTNR_FLG<>'N')) compute statistics ;
I have column containing three values:-N,E,Y.I want to get results with only E and Y values.Is it it possible to create index which would not look for N values.
1DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDITEMID4 2DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDITEMTYPE3 3DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDOWNERID2 4DGT_ITEMEFFORTDATA_DAILYHCLT_IDX_DGT_IFDOWNERTYPE1 There is no index on DGT_ITEMEFFORTDATA_TEMP table
Create small functional indexes for special cases in very large tables.
When there is a column having one values in 99% records and another values that have to be search for, it is possible to create an index using null value. Index will be small and the rebuild fast.
Example
create index vh_tst_decode_ind_if1 on vh_tst_decode_ind (decode(S,'I','I',null),style)
It is possible to do index more selective when the key is updated and there are many records to create more levels in b-tree.
create index vh_tst_decode_ind_if3 on vh_tst_decode_ind (decode(S,'I','I',null), decode(S,'I',style,null) )
To access the record can by like:
SQL> select --+ index(vh_tst_decode_ind_if3) 2 style ,count(*) 3 from vh_tst_decode_ind 4 where 5 decode(S,'I','I',null)='I' 6 group by style 7 ;
1) Split values from "INST" Column : suppose 23 2) Find all values from "NUM" column for above splitted value i.e 23 ,
Eg:
For Inst : 23 , It's corresponding "NUM" values are : 1234,1298
3) Save these values into
A table Y : INST, NUM are column names.
INST NUM 23 1234,1298
1) I have a thousand records in Table X , and for all of those records i need to split and save data into Table Y.Hence, I need to do this task with best possible performance.
2) After this whenever a new data comes in Table X, above 'split & save' operation should automatically be called and append corresponding data wherever possible..
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?
I'm trying to create a ASM disk using oracleasm.I created list the disk (using oracleasm), but the view V$ASM_DISK and ASMCMD (lsdsk command) can't see it..Look:
This is the first time I've got a job in Windows platform, I've worked as DBA with Unix/Linux still now.
I received one command: Install Oracle 11gR2 on Windows 7 Enterprise, so that, I plan to create one Partition (really, not mounted, this is Unallocated partition by Partition Magic 3rd software) which will contain datafile in it.
And, when I install 11gR2 Grid, the step ASM creation did not recognize the Unallocated Partition I created.
In my environment Oracle database 11gR1 is running & dg is configured i.e >> 1 primary & 1 standby. In near future space issues will arise for standby. I want to create 1 more standby with max disk space, but how? Active dataguard is configured where report are generated from where & what changes should be made in Primary pfile & new standby pfile.
I am using 11.2.0.1.0 on RHEL 5.4ASM is properly working on my machine. database is running from ASM. I want to configure additional oracleasm devices.command fails saying:
$ oracleasm createdisk ASMDISK08 /dev/xvd8 Writing disk header: done Instantiating disk: failed Clearing disk header: done
I am creating asm diskgroup on loopback devicesHere are the configured loopback devices.
[root@host1 ~]# ls -l /dev/loop[1-9] brw-rw-rw- 1 oracle oinstall 7, 1 Oct 25 14:42 /dev/loop1 brw-rw-rw- 1 oracle oinstall 7, 2 Oct 25 14:42 /dev/loop2 brw-rw-rw- 1 oracle oinstall 7, 3 Oct 25 14:42 /dev/loop3 brw-rw-rw- 1 oracle oinstall 7, 4 Oct 25 14:42 /dev/loop4
I have two tables with 113M records in DWH_BILL_DET & 103M in prd_rerate_chg_que and Im running following merge query, which is running for 13 hrs to update records, which is quiet longer time.
SQL> explain plan for MERGE /*+ parallel (rq, 16) */ INTO DWH_BILL_DET rq USING (SELECT rated_que_rowid, detail_rerate_flag_code, rerate_sel_key,
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'.
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?
There is a simple way to increase the performance of a query by reducing the row-size of the table it hits. I used it in the past by dividing the table into smaller parts and querying respective smaller table in each query.
what is this method called ? just forgot the method and can't recall it. what this type of row-reduction optimization is called ?
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?
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?
