Need for Read Consistency

Dear Members :
[1] In later versions of Oracle (10g/11) the error "ora-01555 snapshot-too-old" almost never occurs - is this true ?
[2] Why in the first place need for read-consistency, if that's misleading ?
This is just to convince myself - although I never encountered.
Thanks in advance.
Atanu

user11184124 wrote:
Dear Members :
[1] In later versions of Oracle (10g/11) the error "ora-01555 snapshot-too-old" almost never occurs - is this true ? The important word here is almost which comes along with many things. If you have a sufficiently sized Undo tablespace and a properly configured Undo Retention period, its possible that you won't hit the 1555 error any time soon but that doesn't mean its gone for good. Its very much there and can definitely hit you.
[2] Why in the first place need for read-consistency, if that's misleading ?
This is just to convince myself - although I never encountered.
I have given a reply for this in the below thread which also asked the same question. Have a read,
about read consistency
HTH
Aman....

Similar Messages

Special authorization need for read cluster table??

In one report, I use following coding to read information from RFDT table:
form get_f110_parm .
f110id-laufd   = p_laufd.
f110id-laufi   = p_laufi.
f110versionpar = space.
clear:   buktab, fkttab, slktab, sldtab, trctab, usrtab,
           faetab, jobtab, f110v, f110c, trcopt, f110versionpar.
import buktab fkttab slktab sldtab trctab usrtab
         faetab jobtab f110c trcopt f110versionpar
         from database rfdt(fb) id f110id
         accepting padding.
endform.                    " GET_F110_PARM
I can fill F110c, trcopt and f110versionpar by this program. But there is no entry in table like fkttab, usrtab.
Is there any authorization need for read cluster table??
Thanks in advance.
Edited by: Amy Xie on Dec 21, 2010 10:41 AM

Hello,
After you run your code, check transaction SU53 to see if any authorization check failed.

Correctly done AIP needed for reader 10.0.1

I just can't seem to get this. Couldn't get for 9.4.2 either.
msiexec /a acroread.msi /p adobetier1update.msp
I click next and next and then it's done.
It says 10.0.1 in add remove programs, but the install is still 10.0.0. The C:\program files\adobe\reader 10.0\reader\acrod32.exe is still 10.0 and not the updated one.
If I install 10.0.0 and then run the update everything is good. I have also tried
msiexec /a adobereader.msi /update update.msp
Why won't it work?

For creation of Reader X (10.0.1) AIP you need to have Reader X AIP first. You can follow the below steps to create Reader X 10.0.1 AIP
Steps to create Reader X AIP
=====================
1. Create a source folder containing Reader X installer.(Either locally or on a secure network share)
2. Create a distribution point which is accessible by users who want to deploy the application.(At this distribution point installer will install uncompressed program files).
3. Click Start, Run and type cmd and press enter.
4. Run command => msiexec /a "Source Path to Reader MSI"
5. On the network location dialog (where to install files) browse to distribution point created in step 2
6. click ok
Steps to add patch 10.0.1 to Reader X AIP
===============================
1. Create a source folder containing Reader X patch file.(Either locally or on a secure network share)
2. Click Start, Run and type cmd and press enter.
3. Run command => msiexec /a " full path to the administrative installation point and installer
file that you created in the previous procedure at distribution point" /p "full path to Reader patch file"
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About read consistency

Dear Guys
i m getting confused in read consistent image of oracle
please clear a little
suppose if i fired a query that takes 20 min to retrieve data...now its in processing when a B user update some of the rows and fired commit in between..suppose after 5 mins when A fired query
Now please tel A after 20 mins would get the updated rows or same image as it was when started query means old rows data

user11221081 wrote:
Dear Guys
i m getting confused in read consistent image of oracle
please clear a little
suppose if i fired a query that takes 20 min to retrieve data...now its in processing when a B user update some of the rows and fired commit in between..suppose after 5 mins when A fired query
Now please tel A after 20 mins would get the updated rows or same image as it was when started query means old rows dataYou should tell us that what should happen? Always remember that the databases work following the ACID properties where C stands for consistency. This means, that you must not ever see what is called a dirty read . It means that there must not be the case that you should see two different set of results in a single fetch. If a situation happens like this, the database must ensure that your data must be able to show that image of the data which is consistent to the time from when your query started. This is why you need the read consistent image and your database must follow some way of transaction isloation level which in Oracle database is read committed . This means that never ever a reader won't worry about writer and writer won't worry about reader (the word is wait but I changed it to worry to make the point clear).
If this doesn't make the things clear to you, read the link that Srini has given to you already.
HTH
Aman....

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Just bought a mac air with OS X v.10.7 Lion, for work I need to read and write NTFS drives, I install MacFuse and NTFS-3G, but it can not mount (recognize?) External HDD, in my MBP with Snow lepard it work just perfectly... help please.

Reinstall MacFuse with the one from http://www.tuxera.com/mac/macfuse-core-10.5-2.1.9.dmg. If that doesn't work, you can use Paragon NTFS for Mac 9.0 which has been designed to work with Lion.

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Need to read Hex data format for Handheld device. (SAP AII RFID )

Hello,
we developed a custom screens for packing, unpacking, tag commission.. etc for handheld device for my client. the Serial number field type is /ain/barcode. Its working fine. but for the new system need to read the Hex format. I created a new field in the screen. but the handheld device is not reading the Serial number in Hex format.
Could anyone suggest me how to read Hex data in Handheld devices. We are using Motorola MC9090 Series.
Regards,
Kamal

Hi
Are you using the reader to read an RFID tag or for reading barcodes.
Ideally, if you read an EPC Gen2 RFID tag, for example, the 96 bit encoded EPC is read and that can be converted to its equivalent HEX format for posting the observation to SAP AII.
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Need to read all entris for field prtxt from table /sapsll/prt

hi
i need to read all entries from table /sapsll/prt field prtxt but only one is coming
pls see below seelct statement
if not gt_sagmeld[] is initial.
            SELECT /sapsll/cuit~guid_cuit         " PK
                   /sapsll/cuit~QUANT_FLT         " to be displayed
                   /sapsll/cuit~QUAUM             " to be displayed
                   /sapsll/cuit~RPTDT             " to be displayed
                   /sapsll/cuit~guid_cuhd
                   /sapsll/cuit~guid_pr           " needed for gt_prt inttab
                  /sapsll/corref~refno
                   /sapsll/corref~guid_pobj
            INTO corresponding fields of table gt_sapsllcuit
            FROM ( ( /sapsll/cuit
            inner join /sapsll/cuhd on /sapsll/cuit~guid_cuhd = /sapsll/cuhd~guid_cuhd )
            inner join /sapsll/corref on /sapsll/corref~guid_pobj = /sapsll/cuhd~guid_cuhd )
            FOR all entries in gt_sagmeld
            WHERE /sapsll/cuit~guid_cuit = gt_sagmeld-guid_pobj.
         endif.
        if not gt_sapsllcuit[] is initial.
         select /sapsll/prt~prtxt
                /sapsll/prt~guid_pr
         into corresponding fields of table gt_prt
         from /sapsll/prt
         for all entries in gt_sapsllcuit
         where /sapsll/prt~guid_pr = gt_sapsllcuit-guid_pr.
loop at gt_sagmeld into wa_sagmeld.
read table gt_sapsllcuit into wa_sapsllcuit
with key guid_cuit = wa_sagmeld-guid_pobj
binary search.
Read table gt_prcon into wa_prcon with key
guid_pr = wa_sapsllcuit-guid_pr.
if sy-subrc = 0.
*wa_sagmeld_outtab-guid_pr = wa_prt-guid_pr.
here i am facing problem as multiple entries from table /sapsll/prt is not being displayed only one.....but i have checked in table it is having two enteries
pls suggest
reagards
Nishant

Hi Nishant!
When you use 'for all entries' SAP (or database?) does a 'delete adjacent duplicates' on the result. This is necessary because of the special selection technique in this case.
You need to select enough columns from /sapsll/prt, so that your two entries will differ in the result.
Regards,
Christian

I don't want Adobe to open up and be selected immediately. I work with iPhoto and Ipages etc and preview which needs to be my main application for my work , but need adobe reader for other files... how can I do this please?

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loopiloo1 wrote:
I don't want Adobe to open up and be selected immediately.
Sorry, I don't understand this - you don't want Adobe [Reader] not to open when doing what? On what operating system?

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I have spent 3-4 months downloading, buying and searching for an app that would read my books, my magazine subscription based articles and other written information resources. I can NOT find 1 that works and the ones that are dedicated (like Kindle) will not work even on a book I bought from Amazon and chose to save to my iPad kindle app. Their is not even an app I can find for the books and manuals I purchased from my iBook account and the Subscriptions I have their. I can't even find an app that would read passages from my NEBible. Can anyone, anywhere from Earth to the farthest reaches of the Universe, advise me of an app, or apps, that I can Buy, Rent, Lease or anything else an app, or whatever, that would read my books etc. to me? This is very important to me as being disabled and having adjustments to make to get info into me is a bit harder than it used to be. I would really appreciate any and all help I can get.
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http://portables.about.com/od/ipadslatetablets/ss/More-Ipad-Tips-And-Tricks_2.ht m
 Cheers, Tom

Help needed for writing query

help needed for writing query
i have the following tables(with data) as mentioned below
FK*-foregin key (SUBJECTS)
FK**-foregin key (COMBINATION)
1)SUBJECTS(table name)
SUB_ID(NUMBER) SUB_CODE(VARCHAR2) SUB_NAME (VARCHAR2)
2           02           Computer Science
3           03           Physics
4           04           Chemistry
5           05           Mathematics
7           07           Commerce
8           08           Computer Applications
9           09           Biology
2)COMBINATION
COMB_ID(NUMBER) COMB_NAME(VARCHAR2) SUB_ID1(NUMBER(FK*)) SUB_ID2(NUMBER(FK*)) SUB_ID3(NUMBER(FK*)) SUBJ_ID4(NUMBER(FK*))
383           S1      9           4           2           3
384           S2      4           2           5           3
---------I actually designed the ABOVE table also like this
3) a)COMBINATION
COMB_ID(NUMBER) COMB_NAME(VARCHAR2)
383           S1
384           S2
b)COMBINATION_DET
COMBDET_ID(NUMBER) COMB_ID(FK**) SUB_ID(FK*)
1               383          9
2               383          4
3               383          2
4               383          3
5               384          4
6               384          2
7               384          5
8               384          3
Business rule: a combination consists of a maximum of 4 subjects (must contain)
and the user is less relevant to a COMB_NAME(name of combinations) but user need
the subjects contained in combinations
i need the following output
COMB_ID COMB_NAME SUBJECT1 SUBJECT2      SUBJECT3      SUBJECT4
383     S1     Biology Chemistry      Computer Science Physics
384     S2     Chemistry Computer Science Mathematics Physics
or even this is enough(what i actually needed)
COMB_ID     subjects
383           Biology,Chemistry,Computer Science,Physics
384           Chemistry,Computer Science,Mathematics,Physics
you can use any of the COMBINATION table(either (2) or (3))
and i want to know
1)which design is good in this case
(i think SUB_ID1,SUB_ID2,SUB_ID3,SUB_ID4 is not a
good method to link with same table but if 4 subjects only(and must) comes
detail table is not neccessary )
now i am achieving the result by program-coding in C# after getting the rows from oracle
i am using oracle 9i (also ODP.NET)
i want to know how can i get the result in the stored procedure itsef.
2)how it could be designed in any other way.
any help/suggestion is welcome
thanks for your time --Pradeesh

Well I forgot the table-alias, here now with:
SELECT C.COMB_ID
, C.COMB_NAME
, (SELECT SUB_NAME
FROM SUBJECTS
WHERE SUB_ID = C.SUB_ID1) AS SUBJECT_NAME1
, (SELECT SUB_NAME
FROM SUBJECTS
WHERE SUB_ID = C.SUB_ID2) AS SUBJECT_NAME2
, (SELECT SUB_NAME
FROM SUBJECTS
WHERE SUB_ID = C.SUB_ID3) AS SUBJECT_NAME3
, (SELECT SUB_NAME
FROM SUBJECTS
WHERE SUB_ID = C.SUB_ID4) AS SUBJECT_NAME4
FROM COMBINATION C;
As you need exactly 4 subjects, the columns-solution is just fine I would say.

Best practice for read-only functionality

Hi,
I'm part of the development team of a system with about 100 screens. The customer would like us to add some read-only functionality to the system, so that certain users are able to access the screens but not change any of the data on them. We already have policies in place on the database level that keeps read-only users from saving data, but it's not very user friendly to allow users to change data on a screen, only to tell them that they're not allowed to save those changes once they try to do so. It would clearly be better if all components are rendered as read-only components for read-only users, making them unable to make any data changes in the first place.
User privileges in the system are controlled by roles defined and set in the system (not ADF roles or Weblogic roles). At any given time and place, it's possible to check whether the current user has a certain role. We already use this in a number of places to make it possible to control which user has access to which screens. In a few places we even control which functionality should be enabled for the current user within a screen, but mostly the access control is currently on the screen level. With read-only users getting access to all screens, it seems we will need lot of extra in-screen access control to keep these users from changing anything.
But what's the best practice here? One way to go would be to add some logic to every single active component on every single screen, to determine whether it should be rendered as active or disabled/read-only. But that would require a lot of extra coding.
So my question is: Is there a smarter way to do this? Maybe something done through skinning? Or something else?
(I'm not sure how relevant this is for this sort of question, but we're currently using JDev 11.1.1.4.0, and expect to upgrade to 11.1.1.6.0 within the next 6 months)
Best regards,
Andreas

Hi Guna, Puthanampatti and Don,
Thanks a lot for your replies. I'm currently looking into implementing something along the lines of what Guna has suggested:
Our application consists of a number of individual work spaces that are deployed as adflibs which have all been added to a "master application work space", and the master application is deployed as an .ear file. Most of the individual work spaces are for all the different functional areas of the application, with their own task flows, page fragments etc. The rest are work spaces with common functionality, like datamodel (entity definitions), utility methods, page templates, and framework extensions. In the latter, we have defined custom classes for all the base classes (somewhat similar to what Don describes, I believe).
In our custom class for ViewRowImpl, I have added an isAttributeUpdateable method, and in our custom class for ApplicationModuleImpl I have added an isReadOnlyUser method. The isAttributeUpdateable method uses the isReadOnlyUser method to determine if the current user is a read-only user or not; if the user is a read-only user the isAttributeUpdateable method will return false, otherwise true. The isReadOnlyUser method in our base class is just a dummy method that always returns true. But in the ApplicationModuleImpl classes of our individual work spaces, i've written an override for isReadOnlyUser, giving the answer that is relevant for the work space in question (for instance, whether or not the current user has the role "User Administrator").
That pretty much takes care of all input fields in tables and forms, which is a big step in the right direction. This still leaves some work to be done for components that are not directly linked to view object attributes (like buttons), but I guess that can't be helped. Also, there are a few of the work spaces that contain a number of pages that are related to different user privileges (as in: page 1 requires user privilege A, and page 2 requires user privilege B); in these cases I will have to do something different than just writing an override in the "local" ApplicationModuleImpl class.
@Don: What you describe seems to be pretty close in functionality to what we already have, though your implementation is different from ours. You have used your custom base ApplicationModuleImpl class to keep read-only users from committing changes. We use Virtual Private Database and database policies to the same end: If a user without the required full-access role tries to commit data it will cause a database error, which we then handle in the application (so the user gets a message like "You don't have the required privileges to changes this data", rather than an ORA message). Unfortunately, our customers are not content with this. They want a solution where all input fields and most of the buttons etc. are disabled for read-only users, and that's why I'm looking into the best/smartest way to do this.
@Puthanampatti: We already use something similar to what you're suggesting. The challenge I'm currently facing is how best to disable/enable components based on the current user's roles, not how to determine and store those roles.
Best regards,
Andreas

Need for multiple ASM disk groups on a SAN with RAID5??

Hello all,
I've successfully installed clusterware, and ASM on a 5 node system. I'm trying to use asmca (11Gr2 on RHEL5)....to configure the disk groups.
I have a SAN, which actually was previously used for a 10G ASM RAC setup...so, reusing the candidate volumes that ASM has found.
I had noticed on the previous incarnation....that several disk groups had been created, for example:
ASMCMD> ls
DATADG/
INDEXDG/
LOGDG1/
LOGDG2/
LOGDG3/
LOGDG4/
RECOVERYDG/
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Pool #2...has ASM33 - ASM48 volumes....each of which is about 16GB in size.
I used ASM33 from pool#2...by itself to contain my cluster voting disk and OCR.
My question is....with this type setup...would doing so many disk groups as listed above really do any good for performance? I was thinking with all of this on a SAN, which logical volumes on top of a couple sets of RAID5 disks...the divisions on the disk group level with external redundancy would do anything?
I was thinking of starting with about half of the ASM1-ASM31 'disks'...to create one large DATADG disk group, which would house all of the database instances data, indexes....etc. I'd keep the remaining large candidate disks as needed for later growth.
I was going to start with the pool of the smaller disks (except the 1 already dedicated to cluster needs) to basically serve as a decently sized RECOVERYDG...to house logs, flashback area...etc. It appears this pool is separate from pool #1...so, possibly some speed benefits there.
But really...is there any need to separate the diskgroups, based on a SAN with two pools of RAID5 logical volumes?
If so, can someone give me some ideas why...links on this info...etc.
Thank you in advance,
cayenne

The best practice is to use 2 disk groups, one for data and the other for the flash/fast recovery area. There really is no need to have a disk group for each type of file, in fact the more disks in a disk group (to a point I've seen) the better for performance and space management. However, there are times when multiple disk groups are appropriate (not saying this is one of them only FYI), such as backup/recovery and life cycle management. Typically you will still get benefit from double stripping, i.e. having a SAN with RAID groups presenting multiple LUNs to ASM, and then having ASM use those LUNs in disk groups. I saw this in my own testing. Start off with a minimum of 4 LUNs per disk group, and add in pairs as this will provide optimal performance (at least it did in my testing). You should also have a set of standard LUN sizes to present to ASM so things are consistent across your enterprise, the sizing is typically done based on your database size. For example:
300GB LUN: database > 10TB
150GB LUN: database 1TB to 10 TB
50GB LUN: database < 1TB
As databases grow beyond the threshold the larger LUNs are swapped in and the previous ones are swapped out. With thin provisioning it is a little different since you only need to resize the ASM LUNs. I'd also recommend having at least 2 of each standard sized LUNs ready to go in case you need space in an emergency. Even with capacity management you never know when something just consumes space too quickly.
ASM is all about space savings, performance, and management :-).
Hope this helps.

Color management help needed for adobe CS5 and Epson printer 1400-Prints coming out too dark with re

Color management help needed for adobe CS5 and Epson printer 1400-Prints coming out too dark with reddish cast and loss of detail
System: Windows 7
Adobe CS5
Printer: Epson Stylus Photo 1400
Paper: Inkjet matte presentation paper with slight luster
Installed latest patch for Adobe CS5
Epson driver up to date
After reading solutions online and trying them for my settings for 2 days I am still unable to print what I am seeing on my screen in Adobe CS5. I calibrated my monitor, but am not sure once calibration is saved if I somehow use this setting in Photoshop’s color management.
The files I am printing are photographs of dogs with lots of detail I digitally painted with my Wacom tablet in Photoshop CS5 and then printed with Epson Stylus 1400 on inkjet paper 20lb with slight luster.
My Printed images lose a lot of the detail & come out way to dark with a reddish cast and loss of detail when I used these settings in the printing window:
Color Handling: Photoshop manages color, Color management -ICM, OFF no color adjustment.
When I change to these settings in printer window: Color Handling: Printer manages color. Color management- Color Controls, 1.8 Gamma and choose Epson Standard it prints lighter, but with reddish cast and very little detail and this is the best setting I have used so far.
Based on what I have read on line, I think the issue is mainly to do with what controls are set in the Photoshop Color Settings window and the Epson Printer preferences. I have screen images attached of these windows and would appreciate knowing what you recommend I enter for each choice.
Also I am confused as to what ICM color management system to use with this printer and CS5:
What is the best ICM to use with PS CS5 & the Epson 1400 printer? Should I use the same ICM for both?
Do I embed the ICM I choose into the new files I create?
Do I view all files in the CS5 workspace in this default ICM?
Do I set my monitor setting to the same ICM?
If new file opens in CS5 workspace and it has a different embedded profile than my workspace, do I convert it?
Do I set my printer, Monitor and PS CS5 color settings to the same ICM?
Is using the same ICM for all devices what is called a consistent workflow?
I appreciate any and all advice that can be sent my way on this complicated issue. Thank you in advance for your time and kind help.

It may be possible to figure out by watching a Dr.Brown video on the subject of color printing. Adobe tv
I hope this may help...............

Problem due to read consistency...

Hi,
Pls hv look on given scenario...
Two transactions updating the same row
Session 2's update waits until Session 1's commit release the row lock.
In Session 1
SQL>select color from cust where id=500;
color
red
SQL>update cust set color='blue' where id=500;
In Session 2
SQL> select color from cust where id=500;
color
red
SQL>update cust set color=green where id=500;
(Waiting...)
In Session 1
SQL> COMMIT;
In Session 2
SQL>select color from cust where id=500;
color
green
SQL>COMMIT;
Due to read consistency second user never knows that someone had changed color to 'blue'.
We can use flags etc to trap this.
Is there any way in Oracle to stop this logical inconsistency ....?

> I can use select ...for update for the purpose. but there r few reasons for
not using this...
We use JAVA with Oracle.
Not a valid reason. If the language is incapable, or the application server is incapable, then change it.
You cannot blame the RDBMS for not working when the problem is solely with the language/app server. And you will have the exact same problem with any RDBMS as the lock-row-before-updating is a fundamental RDBMS rule for protecting data integrity and guarding against lost updates.
> If Java program crashes then the lock not get automatically released from
Oracle.
I'm not sure that this is a valid statement. I deal with Java apps from JBoss against my databases and I've yet to see this problem.
But for the moment, let us assume you are correct - what happens when the Java app crashes after the UPDATE and before the COMMIT? The exact same problem. So how do you solve this? You cannot simply just ignore those locks and pretend that the locks created by the SELECT FOR UPDATE is a problem.
Also, why are your Java programs crashing so much? If it does not work, fix it or replace it.
> Any idea ?
You can use optimistic locking. This is not preferable. It results in a serious performance issue (and data concurrency issues) with any kind of higher volume OLTP system.
But when dealing with stateless clients (typical 3 tier architecture using web browser clients), there is no choice but to use optimistic locking. E.g.
SELECT c.* INTO :existing_row FROM cust WHERE id = :0
.. processing..
UPDATE cust
SET colour = :new_colour
WHERE custid = :0
AND cust_col1 = :existing_row.cust.col1
AND cust_col2 = :existing_row.cust.col2
AND cust_coln = :existing_row.cust.coln
In other words, the UPDATE checks that the row has not been changed since it was last "seen". If the UPDATE returns a 0 row result, it means that the row has changed. In which case the app needs to handle that exception somehow.

Need for Read Consistency

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