Commit inside For Loop

Hi,
I have a query which is updating millions of records and is inside a for loop . I have issued commit inside that for loop only . Which one will be better . Should I issue the commit inside the for loop or outside it .
Thanks in Advance,
Rahul Guha Ray

No it is not technically true but ajallen has a valid point. Under traditional rollback segment management reading and updating the same table where large quantities of data were changed with frequent committing was probably the number one cause of snapshot too old errors. However, there are many factors that play into this so even under traditional rollback segment management how likely you are to get an error depends: total size of transaction, total run time, concurrent access, and amount on rollback space available.
With undo segment space management it largely depends on the total transaction size and runtime verse how much undo you have and your retention policy.
At some point re-opening the query may indeed be a good idea. One approach is to code to re-open the query only on getting the 1555 error. Some updates however cannot be resumed easily as the update does not mark the row in such a way as the query or where clause conditions can exclude it. In cases like this saving restart information with each commit is necessary.
A lot of different factors have to go into the decision of how often to commit.
-- Mark D Powell --

Similar Messages

How do we use if statement in labview?moreover can i use if statement inside for loop?

how do we use if statement in labview?moreover can i use if statement inside for loop?

The if statement in LabVIEW is the Case structure. You can find that on the Structures palette right next to the For Loop. If you're still on the same subject about terminating a for loop early, then what you do is enclose your functions inside the loop with a case statment and make one of the case's empty except for one or more constants that you might have to wire. Hopefully, the attached picture will explain what I mean. Also, as I mentioned in one of your other posts, I think this technique is not as good as using a while loop. The array in the attached example is the same size no matter what and you may have to handle stripping extra or invalid elements.
Attachments:
For_Loop_with_Case.jpg ‏21 KB

Best practice: Using break statement inside for loop

Hi All,
Using break statment inside FOR loop is a best practice or not?
I have given some sample code:
1. With break statement
2. With some boolean variable that decide whether to come out of the loop or not.
for(int i = 0; i < 10; i++){
if(i == 5){
break;
boolean breakForLoop = false;
for(int i = 0; i < 10 && !breakForLoop; i++){
if(i == 5){
breakForLoop = true;
The example may be a stupid one. But i want to know which one is good?
Thanks and Regards,
Ashok kumar B.

Actually, it's bad practice to use break anywhere other than in conjunction with a switch statement.Presumably, if you favour:
boolean test = true;
while (test)
test = foo && bar;
if (test)
}overfor (;;)
if (! ( foo && bar) ) break;
}then you also favour
boolean test = foo && bar;
if (test)
}overif (foo && bar)
}Or can you justify your statement with any example which doesn't cause more complexity, more variables in scope, and multiple assignments and tests?

Is it possible to put property node inside for loop?

I have created three separate property nodes (plot color) for my 3 XY graphs.
Is it possible to have one property node, say plot_color_i and put this inside the for loop where i runs from 1 to N,
where plot_color_1 would update XY Graph 1, plot_color_2 would update XY Graph 2, etc.?
See the attached VI.
Solved!
Go to Solution.
Attachments:
XY Plot Example.vi ‏18 KB

Yes. Create an array of references of the XY graphs and have that auto-index into the property node in the For Loop
Attachments:
XYPlotExampleMOD.vi ‏18 KB

Stacked sequence inside for loop question

Hi everyone,
I am new to LabVIEW and I just want to make a for loop with a stack sequence inside. I want it so that when the for loop executes for the n-th time, the stacked sequence is at the n-th frame (because each frame contains different tasks to be carried out). Is this possible? or is there an alternative equivalent method? Please help me out! Thanks!!

Thank you Norbert for the words of advice.
Try to avoid Stacked Sequence Structures at all cost. They are a nightmare to deal with when maintaining the code and they do not offer simple scalability, especially if you need to deal with parallelism.
As Norbert suggested, State Machines is the way to go. Try to avoid naming covention such as 1...2...3...4...5.......9999. Give the name of each case based on what that case does. Create a TypeDef Control for the state selector (you'll thank me after having changed it for the 5th time ).
There are probably 100's of examples in this forum.
RayR

State Diagram inside For Loop

I created a fairly involved for-loop with a flat sequence inside of it. The sequence had about four events that occured, and since it was kind of ugly, I thought I'd try the State Diagram Toolkit to replace the majority of the code. When I selected state diagram from the pallete, I was outside my for-loop. I drew up the various states/transitions, then realized that all this code needed to be inside the for-loop, but LV won't let me place state diagram-generated code inside the for-loop. I select everything related to the state diagram, but when I drag into the for-loop, only the comments come inside. I even tried generating a new for-loop and placing the state code inside. No luck. Any thoughts?

"Any thoughts?"
Yes but not any that will help.
1) Just modify your SD so that the exit loops back to the start while there are still things to do. Forget the outer For loop.
2) THe observations you reported are correct. When I first discovered these limitiations I said "That sucks!". Since then I have learned a bit and have grown to love the SDE.
The SDE is JUST (note: "just" is a four letter word around here ) a LV application that ofers a very limited GUI consisting of a picture control that then scripts (see LAVA Scripting Forum for info on scripting) your SD for you. SCripting LV code is no easy task. My experiments with scripting has shown that I have to keep a database of the contents of the LV diagram my code is developing to keep track of what is where. Well it turns out that the structure of a LV diagram is a lot like the structure of a FP in that you start with a "root" object either the FP or the BD. THe BD then has structures on it, like seq's loops etc with unlited nesting possible.
Now the SD created by the SDE is really just a fancy while loop with an case structure and code to support the driving enum. In order for you to be able to edit the SD the SDE needs to know what is htere already so it can show the diagram. It "KNOWS" by looking at its internal DB (I believe is stored inside of VI along with the enum.ctl) of the SD. To keep the DB updated, the SDE must be used to manipulate the SD.
Stop rambling and guessing and get to the point!
Moving the SD is just not supported by the SDE so it can not be done. To do so would require the SDE be able to "look" at the diagram, and repeat all of its work in the new location in the diagram.
BTW: Thank you for trying out and asking about the SDE. the more talking we do on this subject, the sooner the SDE will be updated.
My SDE wishlist (partial)
Add comments to diagram from SDE screen.
Add data structures to SD (shift registers) from SDE screen.
Add "un-do".
Select multiple objects on SDE screen and move or allign.
Select multiple objects on SDE screen and do "create sub-State-Diagram".
Allow watching more than one SDE in execution highlighting at the same time.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Initializing variables inside for-loop?

Dear all,
It's been a while since I last programmed in Java, and my skills seem to be a bit rusty.
I have a question for you here: suppose I need to initialize n (let's say 10) different integers, I suppose I couldn't use something like this:
for(int i = 0; i < 10; i++){
int <¿VALUE?> = i;
}Is there a way to dynamically initialize <VALUE>, for instance something like ("integer" + i)? (integer0=0, integer1=1, integer2=2, etc.)
Thank you,
Maarten

You need to declare the arrays in a context outside of the for loop, the for loop context will end and so will all of your locally declared variables. Now there is a way around that:
Make an ArrayList, in a "Global context" to your loop, and initialize your variables in the for loop, then add them to the ArrayList, once you are out of the loop, then the ArrayList will hold your references to your variables and keep them from being disposed. When you are done with them, then just remove them from the ArrayList.
ArrayList<myNodes> al = new ArrayList<myNodes>(); //in a "global context"
for(int i=0; i<iSomeNumber; i++){
MyNode n = new myNode();
//do what ever
al.add(n);
}If you need key values to look up your nodes by, then you a Map of some type instead of an ArrayList.

Commit in a loop of records for the cursor

Hello
my procedure has the following structure
procedure proc2
BEGIN
begin
insert into table A
exception when others
log the error
return
end
begin
insert into table B
exception when others
log the error
return
end
END--end of proc2
--main procedure
open cursor
loop
fetch cursor
proc2
end loop;
commit;
end;-- end of main
my question is do i need to commit inside the loop , also since i have exception handling for all the inserts, if any one of the inserts fails then it should log the error, and go to the next record.., or will it roll back all the previous insert operations since the commit is outside the loop in other words if the there are 10 records in the cursor, and the insert fails at 9th record will oracle roll back all the previous insert operations???
thanks
abhishek

my question is do i need to commit inside the loop ,depends if you want to commit rigth away or if you want to include a counter to check when you want to commit
also since i have exception handling for all the
inserts, if any one of the inserts fails then it
should log the error, and go to the next record.., right
or will it roll back all the previous insert operations
since the commit is outside the loop in other words
if the there are 10 records in the cursor, and the
insert fails at 9th record will oracle roll back all
the previous insert operations???based on your logic if you had exceptions it will skip to the next record

For Loop Inside A For Loop

Is it possible to execute all the iterations of the inside for loop for each iteration of the outside for loop? I have attached a screenshot of my program if it helps. If it is possible could you tell me how to do it plz?
Solved!
Go to Solution.
Attachments:
Capture.PNG ‏53 KB

One thought I have is that I think you want those feedback nodes reinitializing for each iteration of the outter loop. Personally, I would change them to be shift registers (it would clean up your diagram a little bit).
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Read data from text file one by one using for loop

Dear Forum
I want to read data of single colum of text file inside the for loop one by one(for each iteration value must be replaced by another value of text file).This value is used by a formula inside for loop. also after completion of iterations the values must be plotted on xy graph. How to do it.? please help me.
profravi

It's not very efficient to read a file line by line. Much simpler to read it all at once and then auto-index the results inside a for loop. The image below shows a generic solution to your problem. This assumes that the data in the file is in a single column.
I would also recomend checking ou the learning LabVIEW resources here.
I would aslos suggest that since this type of question is not specific to either NI-Elvis or the LabVIEW SE, you should post similar questions to the LabVIEW board. If you have problems, attaching a sample of the text file would help.
Message Edited by Dennis Knutson on 10-18-2007 09:11 AM
Attachments:
XY Graph From File.PNG ‏4 KB

How to output data outtside a for loop every 10 iterations?

Hi friends,
does any body help me to sort out this problem?
please check the attchement for my vi.
all i want is output data from inside for loop to outside for loop every 10 iterations. please do not use local variable.
Many thanks
dan
Attachments:
output.vi ‏16 KB

Hi Dan,
I am not sure what you want to do every 10 iterations with the value outside, but If you want to update your graph every 10 iterations use the following way:
If you want to handle the specific value every x iterations outside the loop you could either use queues or notifieres.
BR,
ThSa
Message Edited by ThSa on 08-23-2006 09:05 PM
http://www.newgistics.com
Attachments:
1.png ‏6 KB

Just wanna do a for loop

Just wanna do a for loop by using a method. The error I'm getting is
java:6: missing return statement
public int for1(){
^
1 error
import java.util.*;
public class forloop{
     public int for1(){
          for(int i = 1; i <= 100; i++){
               System.out.println(i);
               return i;
     public static void main(String args[]){
          forloop a = new forloop();
          a.for1();

Oh i see the problem was i didn't declare i in the
class before i used it in the method definition. I
thought the way i declared it in the for loop would
work, oh well.no-no. the problem was, that you returned something only inside for loop, but compiler was not sure that thing from the for loop would be returned, so it was bitching about that...
if you had written your for statement like that:
for (int i=0; i < -1; i++) {
return i;
then body of return statement would not had been executede, therefore nothing would have got returned, and that's the case about what this compiletime error was telling you...

Commit after every three UPDATEs in CURSOR FOR loop

DB Version: 11g
I know that experts in here despise the concept of COMMITing inside loop.
But most of the UPDATEs being fired by the code below are updating around 1 million records and it is breaking our UNDO tablespace.
begin
for rec in
      (select owner,table_name,column_name
      from dba_tab_cols where column_name like 'ABCD%' and owner = p_schema_name)
      loop
        begin
        execute immediate 'update '||rec.owner||'.'||rec.table_name||' set '||rec.column_name|| ' = '''||rec.owner||'';
        end;
      end loop;
end;We are not expecting ORA-01555 error as these are just batch updates.
I was thinking of implementing something like
FOR i IN 1..myarray.count
LOOP
                         DBMS_OUTPUT.PUT_LINE('event_key at' || i || ' is: ' || myarray(i));
                         INSERT INTO emp
                         empid,
                         event_id,
                         dept,
                         event_key
                         VALUES
                         v_empid,
                         3423,
                         p_dept,
                         myarray(i)
                         if(MOD(i, p_CommitFreq) = 0) --- When the loop counter becomes fully divisible by p_commit_frequency, it COMMITs
                         then
                                   commit;
                         end if;
END LOOP;(Found from an OTN thread)
But i don't know how to access the loop counter value in a CURSOR FOR loop.

To be fair, what is really despised is code that takes an operation that could have been performed in a single SQL statement and steps through it in the slowest possible way, committing pointlessly as it goes along (exactly like the example you found). Your original version doesn't do that - it looks more like some sort of one-off migration where you have to set every value of every column that matches some naming standard pattern to a constant. If that's the case, and if there are huge volumes involved and you can't simply add a bit more undo, then I don't see much wrong with committing after each update, especially if you track how far you've got so you can restart cleanly if it fails.
If you really want an incrementing counter in an unnamed cursor, apart from the explicit variable others have suggested, you could add rownum to the cursor (alias it to something that isn't an Oracle keyword), although it could complicate the ORDER BY that you might be considering for the restart logic. You could have that instead of the redundant 'owner' column in your example which is always the same as the constant p_schema_name.
Another approach would be to keep track of SQL%ROWCOUNT after each update by adding it to a variable, and commit when the total number of rows updated so far reaches, say, a million.
Could the generated statement use a WHERE clause, or does it really have to update every row in every table it finds?
Could there be more than one column to update per table? If so it might be worth generating one multi-column update statement per table, although it'll complicate things a bit.
btw you don't need the inner 'begin' and 'end' keywords, and whoever supplied the MOD example you found should know that three or four spaces usually make a good indent and you don't need brackets around IF conditions.

I have a for loop inside of while loop.when i press stop for while loop, i also would like to stop for loop.how can i solve this problem?thanks

i have a for loop inside of while loop.when i press stop for while loop, i also would like to stop for loop.how can i solve this problem?thanks

Hi fais,
Following through with what JB suggested. The steps involved in replacing the inner for loop with a while loop are outlined below.
You can replace the inner for loop with a while by doing the following.
1) Right-click of the for loop and select "Repalce" then navigate to the "while loop".
2) Make sure the tunnels you where indexing on with the for loop are still indexing.
3) Drop an "array size" node on your diagram. Wire the array that determines the number of iterations your for loop executes into this "array size".
4) Wire the output of the array size into the new while loop.
5) Set the condition terminal to "stop if true".
6)Drop an "OR" gate inside the while loop and wire its output to the while loops condition terminal.
7) C
reate a local of the boolean "stop" button, and wire it into one of the inputs of your OR gate. This will allow you to stop the inner loop.
8) Drop a "less than" node inside the inner while loop.
9) Wire your iteration count into the bottom input of the "less than".
10) Wire the count (see step 4 above) into the top input of the less than. This will stop the inner loop when ever the inner loop has processed the last element of your array.
Provided I have not mixed up my tops and bottoms this should accomplish the replacement.
I will let others explain how to takle this task using the "case solution".
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Strange System.out.print behavior inside a for loop

I'm trying to create a simple ASCII progress bar in the console that would display like this:
|--------------------------------------------|
============================More equal signs would appear as time goes on. At least this is what I want to happen.
Instead, what happens is, none of the equal signs are printed until the very end, after the for loop in which the System.out.print("=") statement is in, has exited.
This is my code (probably more than necessary is shown, but the important part is the for loop):
    public void addSomeDiffys(int numOfDiffys, int minInt, int maxInt) {
        Diffy currentDiffy;
        System.out.println("\nCreating Diffys.");
        System.out.println("|--------------------------------------------|");
        for (int i=0; i < numOfDiffys; i++) {
            currentDiffy = new Diffy(minInt, maxInt);
            if ((i/(double)numOfDiffys)*100 % 2 == 0)
                System.out.print("=");
            diffyList.add(currentDiffy);
        System.out.println("\n" + diffyList.size() + " Diffys created.\n");
        System.out.println("Sorting according to highest rating...");
        Collections.sort(diffyList,Diffy.HIGHEST_RATING_ORDER);
        System.out.println("Done.\n");
    }I also tried changing the System.out.print("="); to System.out.println("="); This time it works as expected, its just not very pretty...
I get something like this:
|--------------------------------------------|
=
=
=
=
=
=
=
=
=
=
=
=So again, when I use println, rather than print, the equal signs are printed over time, slowly, as the progress increases. When using print, Nothing happens for a long time, and then suddenly they all appear after the for loop has terminated, which makes no sense.
Thanks for any help.

When using print, Nothing happens
for a long time, and then suddenly they all appear
after the for loop has terminated, which makes no
sense.
Yes it does make sense! The characters are buffered inside the PrintStream and written when there is a full line to write. You could try a flush() after each = is written but I have no confidence that it will make any difference.

Commit inside For Loop

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