Performance Tuning :: Getting Enq - TS - Contention?
Jul 26, 2011I am getting enq: TS - contention as top event in AWR Report.where can i look into database to fix this issue.
View 14 Replies
ADVERTISEMENT
Performance Tuning :: Tools For Database Tuning And Instance Tuning
Jul 12, 2010Looking 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?
Performance Tuning :: Merge Statement Tuning For 100M Records In Table?
Oct 31, 2011I 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,
[code].....
Performance Tuning :: How Length Of Column Width Effects Index Performance
Sep 30, 2010How 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'.
Performance Tuning :: Fragmentation Can Reduce Performance In Query Times
Jun 16, 2010I 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?
Performance Tuning :: Method Of Tuning Database - Row Reduction?
Oct 20, 2010There 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 ?
Performance Tuning :: Performance Standard Edition Without Partitioning?
Jun 16, 2011How 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?
Performance Tuning :: Procedure Performance On New Database Import?
Nov 15, 2010Testing 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?
Performance Tuning :: Checking Delete Performance In Package
Apr 12, 2013I 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.
Performance Tuning :: Query Performance Gain Using Statistics?
Aug 9, 2010Somewhere 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.
Performance Tuning :: How To Improve The Performance Of Export Job (expdp)
Dec 6, 2011I 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?
Performance Tuning :: DECODE In WHERE CLAUSE Performance?
Oct 17, 2011The following query gets input parameter from the Front End application, which User queries to get Reports.There are many drop down boxes like LOB, FAMILY, BRAND etc., The user may or may not select values from drop down boxes.
If the user select any one or more values ( against each drop down box) it has to fetch all matching values from DB. If the user does'nt select any values it has to fetch all the records, in this case application will send a value 'DEFAULT' (which is not a value in DB ) so that the DB will fetch all the records.
For getting this I wrote a query like below using DECODE, which colleague suggested that will hamper performance.From the below query all the variables V_ are defined in procedure which gets the values selected by user as a comma separated string here V_SELLOB and LOB_DESC is column in DB.
DECODE (V_SELLOB, 'DEFAULT', V_SELLOB, LOB_DESC) IN
OPEN v_refcursor FOR
SELECT /*+ FULL(a) PARALLEL(a, 5) */
*
FROM items a
WHERE a.sku_status = 'A'
[code]...
Performance Tuning :: Same Data But Different Performance Results
Sep 3, 2010what the principal things to look at when we have for the same query different performance results are?I have 2 different bases: the plan and data are the same but performance results are very differents.
View 10 Replies View RelatedPerformance Tuning :: DB Performance Keys?
Mar 17, 2012are the most important performance keys we have to calculate or take in account to preserve or to increase the DB performance in terms of response times, and whatsoever according to performance ?
View 8 Replies View RelatedEnq - TX - Row Lock Contention?
Oct 10, 2012In my current project, I am handling an Oracle database with version 10.2.0.3. I analyzed the AWR report for the past month abd saw the following wait events consistently:
CPU time - 45.6% (% Total Call Time)
db file sequential read - 30.6% (% Total Call Time)
enq: TX - row lock contention - 18.8 % (% Total Call Time)
I have uploaded the report for your reference.What should be my approach to troubleshoot this?
Attached File(s)
awr_report.html ( 382.28K )
Number of downloads: 6
SQL & PL/SQL :: Contention Between JOB_QUEUE_PROCESSES And Processes
Aug 30, 2011In the program i wrote, posted in this thread I parallelize 340 jobs.
To do this, according to oracle documentation, i set the job_queue_processes parameters to 450. This works fine, all jobs are submitted, but, when i chek the dba_scheduler_job_run_details, i notice that there is a difference between REQ_START_DATE, which is my requested start date, when i enabled my job, and the ACTUAL_START_DATE, which is the date on which Oracle start this process.
And the more i submit job, the more difference between ACTUAL_START_DATE and REQ_START_DATE increase. But for each job, run duration is less than 1second. I check the processes parameter, and it is set to 100. if i have to increase the processes parameter to 450 too ?
TX - Index Contention On Update
Sep 3, 2012I have a UPDATE statement which sets values on non-indexes columns and do not use indexed-column in where clause (so every column used in statement are not indexes). Lastly, I had some problem with database and saw in ASH report in TOP SQLs that update with events enq: TX - index contention and buffer busy waits. What does it mean? I read a lot of information about index contention, but always related to INSERT and DELETE. What has UPDATE to do with this contention?
View 3 Replies View RelatedServer Administration :: Contention On Data Blocks?
Oct 22, 2010We are suffering from very bad application response for last few days, when i try to check and drill down, where the actual contention is? I came to know that there may be contention on data blocks, which may be a prime reason for degraded performance. Herewith i'm pasting my actual stats of gathered from v$waitstat. I gone through some of asktom docs and find that there may be a problem with freelist or segment space management. My data tablespace is segment space management = Manual.
My main question is
1) Should i need to increase freelist value (Right now my value is 1)
2) Or i have to move on segment space management = auto
SQL> select * from v$waitstat;
CLASS COUNT TIME
------------------ ---------- ----------
data block 2022 4052
sort block 0 0
save undo block 0 0
segment header 1 1
save undo header 0 0
free list 0 0
extent map 0 0
1st level bmb 0 0
2nd level bmb 0 0
3rd level bmb 0 0
bitmap block 0 0
bitmap index block 0 0
file header block 0 0
unused 0 0
system undo header 0 0
system undo block 0 0
undo header 6 0
undo block 0 0
18 rows selected.
Row Lock Contention - Trace File Shared
Nov 19, 2012I am having enq: TX - row lock contention in top wait event. it is occurring between 10pm - 2am.
We are having sqlloader job running every one hour(conventional path). But for the specific period of time i am getting "Global Enqueue Services Deadlock detected". Between 10-5. I analyzed related trace file it is make me little confusion.I found there are four insert query culprit for this locking. out of four sql , tow of them are ran by same SID, other two insert ran by same id. I got confused because how same sid locking them self. trace file below. during this period oracle maintenance window is active.
Trace file:
*** 2012-10-09 03:40:31.135
user session for deadlock lock 0x15365e060
sid: 1104 ser: 22256 audsid: 8797820 user: 49/iurth flags: 0x45
pid: 71 O/S info: user: oracle, term: UNKNOWN, ospid: 8601
image: oracle@sgh0909
client details:
[code]....
Performance Tuning :: Options While Using RBO?
Mar 27, 2013I am working on an assignement where client is using Oracle 10g but stuck to using RBO Now the application team, from the GUI available to them build dynamic queries and some of them run very slow.
Neither the code can not be changed to tune the queries nor do we get the exact step in the plan which is an issue (being RBO).For some long running queries the Tuning advisor is not producing any recommendations.
Another hurdle is that all the application users are using same application user id so we can not write a logon trigger to use CBO for some particular queries to see what is happening in the background!
Performance Tuning :: Next SQL Sentence
Jul 4, 2012I want to tuning the next sql sentence. In this sql I want to get the hash_value and sql_text of the sentences that it's causing TX blocks. Is it possible?. This sentence works fine but sometimes It's slow.
SELECT DISTINCT hash_value,
sql_text
FROM gv$sql sq
WHERE hash_value IN (SELECT DISTINCT prev_hash_value
FROM gv$session se
WHERE sid IN (SELECT sid
FROM gv$lock l
WHERE type = 'TX'
AND ctime >= 2000
AND l.inst_id = se.inst_id
AND l.sid = se.sid)
AND sq.inst_id = se.inst_id);
[code]....
Performance Tuning :: Different SQL ID For Same HASH-VALUE?
Nov 2, 2012I see one of my SQL's which is ran by the user on a 10.2.0.3 database changing its SQL_ID after some runs even if the query is not changed a bit! However the HASH VALUE for this query remains the same.
how a same query can have different SQL_ID's but same HASH_VALUE?
Note: Statistics are not modified on the base tables of this query.
Performance Tuning :: SGA-MAX-SIZE To More Than 2G?
Aug 10, 2011I am running Oracle 10.2.0.1.0 on MS Windows 2003 server 64-bit with 16G RAM.
Here is the findings for my Oracle database.
SQL> select * * from v$sgainfo;
NAME BYTES RES
-------------------------------- ---------- ---
Fixed SGA Size 1293560 No
Redo Buffers 7094272 No
Buffer Cache Size 830472192 Yes
[code]...
I find that the SGA component "Buffer Cache" is decreasing from the start "1.8G" and down to now 0.8G. On the other hand, the component "Shared Pool" is increasing from the start 0.3G to now 1.2G. I noticed that there are 100 operations of shrinking of "Buffer cache" and growth of "Shared Pool" in Oracle every day.Is it a indicator that I should raise up the SGA_MAX_SIZE?
I tried to increase the SGA_MAX_SIZE to 4G. But I cannot start the Oracle afterward.Is it a limitation of MS Windows(OS) or Oracle?I set the SGA_MAX_SIZE to 3G. This time, I can startup Oracle.What is the optimum/maximum I can set to SGA_MAX_SIZE?Is there any adverse effect/concern when setting the SGA_MAX_SIZE more than 2G?
Performance Tuning :: How To Know Host Name Using Sql ID Or SID
Jul 11, 2012Here i have three tier application. I want to know it host name from sid or sqlid . I want to know which query run on which host. Because i have one user from application to database. So i want to know which query consume more time on which host ?
View 19 Replies View RelatedPerformance Tuning :: No Redo For DML?
Mar 17, 2006How can I disable redo generation for DML statements.
View 25 Replies View RelatedPerformance Tuning :: TPC-E Benchmarking
Aug 14, 2010I want to run some OLTP benchmarks on my system. I have looked up the TPC-E benchmarking suite .. but the documentation on the site makes no sense to me .
View 1 Replies View RelatedPerformance Tuning :: AWR Report Evaluation
May 20, 2010My DB is oracle10g.
I have AWR report comparison for two different days. I want to find the below things.
1. Which day has better performance?
2. What are the top two findings on the report.
I attached the report.
Here are my answer. Please correct me if i am wrong.
1. Which day has better performance? Second day has higher load. Since redosize is showing very high.
2. What are the top two findings on the report.
a) Compared to two days, first day, little bit more I/0 wait for single block read.
b) Compared to two days, 2nd day, it takes higher CPU.
However, which day is best compared to two days?
Performance Tuning :: How To Enable AWR In Oracle 10g
Jul 12, 2013I 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.
Performance Tuning :: Top 5 Timed Events?
Aug 31, 2010In my awr reports I have CPU time(in seconds) as one of top 5 timed events.Does that mean oracle is waiting for my cpu to execute the statements.But my cpu usage is 0-10% always
View 4 Replies View RelatedPerformance Tuning :: How To Reduce Clustering_factor Value
Jun 7, 2012how to reduce the clustering_factor's value which appears in the user_indexes view?
in my table ,its clustering factor's value is so high:
SQL> SELECT UI.clustering_factor,UI.num_rows,UI.index_type,UI.distinct_keys FROM USER_INDEXES UI WHERE UI.table_name = 'TAWB_AWB';
CLUSTERING_FACTOR NUM_ROWS INDEX_TYPE DISTINCT_KEYS
----------------- ---------- --------------------------- -------------
83609 187603 NORMAL 187603
and its block numbers is 5063
SQL> SELECT COUNT(DISTINCT DBMS_ROWID.rowid_block_number(ROWID)) BLOCK_NUM FROM TAWB_AWB A;
BLOCK_NUM
----------
5063