Performance Tuning :: Undo Space?
Jan 15, 2012Query to find out who is eating up most of the undo space and what query he is running..
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Undo Segments In Undo Table Space
Nov 29, 2012Can we find out no of undo segments in undo Table space ? If so , how to find? what's their max limit ?
View 9 Replies View RelatedPerformance Tuning :: ORA-01555 Required Old Image Is Not In Undo
Sep 22, 2011I am getting the below error in alert log file,when my application calling a procedure.
ORA-01555 caused by SQL statement below (Query Duration=1576 sec, SCN: 0x09a2.5dda3165):
Fri Sep 16 16:33:40 2011
UPDATE SSPT_NETWORK_DETAILS SET INCLUDE_OFFERS = 'Yes' WHERE SESS_ID = SESS_ID
There is no ROLLBACK statement in my procedure. As per my understanding, the ORA-1555 error will occur,
1. The required old image is not in the undo,when we rollback the trasaction.
2. the select query may face this error because of delayed block cleanout concept.
But I don't know why this update statement causing this 1555 error?
Performance Tuning :: Undo Tablespace Full / Which Is Rectified But Now Having Big WAIT
Mar 7, 2012we have a situation where both undo tablespaces were almost filled i.e UNDOTBS1 99% and UNDOTBS2 100% filled so i add data files to it and then i found a lot of blocking session and was just killing them through EM then i stop my front end listener and also down the service, now i don't have any blocking session but on EM a big WAIT is coming. alert log shows nothing serious, it was showing deadlock but now it is over as well.
View 8 Replies View RelatedPerformance Tuning :: ORA-01555 - Increase Undo Size Or Retention?
Apr 22, 2013I have got the following error yesterday
ORA-01555 caused by SQL statement below (SQL ID: fdxcyoin67ty8t, Query Duration=380128 sec, SCN: 0x0229.ff00afd0):
following are the existing settings
SQL> show parameter undo
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
undo_management string AUTO
undo_retention integer 96000
undo_tablespace string undo
[code]....
following are the details from v$undostat
select begin_time, end_time, undotsn, undoblks, maxquerylen, maxqueryid, activeblks, unexpiredblks, expiredblks, tuned_undoretention from v$undostat
where trunc(begin_time)=trunc(sysdate)-1 order by begin_time;
BEGIN_TIME END_TIME UNDOTSN UNDOBLKS MAXQUERYLEN MAXQUERYID ACTIVEBLKS UNEXPIREDBLKS EXPIREDBLKS TUNED_UNDORETENTION
-------------- -------------- ---------- ---------- ----------- ------------- ---------- ------------- ----------- -------------------
21-04-13 00:08 21-04-13 00:18 1 12733 378446 duqnawh32hp4u 91152 7068448 225440 345600
21-04-13 00:18 21-04-13 00:28 1 8951 379047 duqnawh32hp4u 99344 7072800 225440 345600
21-04-13 00:28 21-04-13 00:38 1 14073 379650 duqnawh32hp4u 90128 7075872 234656 345600
[code]....
Following are the details in AWR report (00:00 til 01:00 of 21-Apr-2013) .... not thet the error was produced at 00:42
Undo Segment Summary DB/Inst: DBCPY/dbcpy01 Snaps: 18853-18854
-> Min/Max TR (mins) - Min and Max Tuned Retention (minutes)
-> STO - Snapshot Too Old count, OOS - Out of Space count
-> Undo segment block stats:
-> uS - unexpired Stolen, your - unexpired Released, uU - unexpired reUsed
[code]....
Undo Advisor information taken 'now' is as following
SQL> select dbms_undo_adv.longest_query(sysdate-2,sysdate) from dual;
DBMS_UNDO_ADV.LONGEST_QUERY(SYSDATE-2,SYSDATE)
----------------------------------------------
379650
SQL> select dbms_undo_adv.required_retention from dual;
[code]....
In above situation what should be my first choice (assuming increasing space is not an issue) - increase undo tablespace or increase undo retention?
If latter is the choice then what should be the value? Because as I understand present 96000 value is taken as lower limit and because of auto tuning the actual value (TUNED_UNDORETENTION) being used was 345600 In that case shall I set it to something > max(maxquerylen) i.e 379,650 + X?Or I shall increase the undo tablespace size?
From Undo Advisor output it looks to me that even if I increase the undo retention to 379650 current undo size will be able to support it (may be at the expense of DMLs)Is that right?
Performance Tuning :: Temp Tablespace Running Out Of Space (68 GB)?
Nov 17, 2011I am getting temp tablespace error "ORA-01652: unable to extend temp segment by 128 in tablespace TEMP" for the following code.
SELECT /*+ USE_NL ( vd1 ,vd2 ,vd3 ) leading ( vd1 ,vd2 ,vd3 , tvd) */ vd1.vendor_record_seq_no,
tvr.checksum, tvr.rownumber, tvr.transaction_type, 'U'
FROM vendor_data vd1, vendor_data vd2, vendor_data vd3,
(SELECT rownumber, MAX (DECODE (control_column_seq_no, 91150, original_value, NULL)) AS value1,
[code]...
Right now used tables has the following number of records-
SELECT COUNT(*) FROM vendor_data --292890442
SELECT COUNT(*) FROM temp_vendor_data --0
SELECT COUNT(*) FROM temp_vendor_record --0
This query is part of an application, but consuming too much of temporary tablespace (68 GB allocated). I found it out by using query below:
select * from v$session a, v$sql b
where a.sql_id=b.sql_id
and status = 'ACTIVE'
I am not sure, why this problem is occuring.
Performance Tuning :: MVIEW Huge Temp Space?
Nov 23, 2011I run a query, takes 20 minutes or so, I traced it and can see no more then 20-30 mb of temp space required in the plan.
I developed it for use in a materialized view, however when I create the mview with the sql, the temp space required grows until it maxxes out. I increased the existing 10gb to 50gb but still maxxed out. Took the SQL out, reran it, ran in 20 minutes barely scratching the temp, I ran a "create table as <select>" and same behaviour as the SQL, barely touched the temp as per the plan. So the temp space blolwing is unique to the mview create.
Im working with mviews years on several sites and have never seen this.
Alter Table Fails - Ran Out Of Undo Space?
Jun 11, 2009I want to alter a very large table.
ALTER TABLE MYTABLE ADD
(
ENTRY_TSTMP DATE DEFAULT SYSDATE NOT NULL
)
My table is very large and I am getting an error saying I am out of undo space.
The dba says the undo space is as big as the table.
Undo Table Space Not Working - REDO Being Generated?
Feb 14, 2013I am using Oracle 10.2.0.3. Since yesterday i am seeing a session with sid 1160 using undo tablespace but not able to find how much it is using .I need to know which session and from which module and how much is the Undo being used by those sessions. I have tried searching but all the queries provide me with some different results each time.
Also i need the same information for REDO being generated .
What Happens When UNDO Space Is Full / Transaction Takes More Time To ERROR
Jan 26, 2011I have a long running transaction (more than 3 hours), and at the same time other operations are occurring on different tables, using the same UNDO space.
Sometimes we see ORA-30036, but this error occurs very late in the process. The transaction normally takes 3 hours, but when UNDO space is full, we do not get ORA-30036 upto 8 hours or 9 hours of process.
I am wondering what could be happening in the background, when UNDO space is full, which makes the transaction to extend upto 8 hours or 9 hours (pl. note, this transaction gets completed within 3 hours normally). This is in 11g, UNDO space is managed manually.
Server Administration :: Sizing Undo Tablespace And Setting Undo-retention?
Jan 30, 2004regarding sizing undo tablespace and undo_retention parameter.we have to implement the database in production system with 40 users but how much space should be allocated to undo tablespace is there any propotions related to virtual memory and the
parameter.i have gone thru oracle doc's and some related sites.its an ERP aplications that contains 20 modules .I am an new one to this dba level
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 RelatedSQL & PL/SQL :: Replace Double Space With Single Space And Also Remove Junk Characters
Jul 1, 2013I want to replace double space with single space and also remove junk characters from the data. How can I do that?
CREATE TABLE test07013
(
NAME VARCHAR2(50)
);
INSERT INTO VALUES ('WARREN,'); -- REMOVE ","
INSERT INTO VALUES ('CLARK H'); -- REPLACE "DOUBLE SPACE" WITH "SINGLE SPACE"
INSERT INTO VALUES ('BRYAN A.'); -- REMOVE "."
INSERT INTO VALUES ('CARTER JR. ROBERT'); -- REMOVE "."," AND REPLACE "DOUBLE SPACE" WITH "SINGLE SPACE"
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 ?
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