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Error in a large file


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suraaj

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PostPosted: Fri Nov 13, 2015 8:23 pm
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How do you find an error in a large file without using a debugger tool? This is an interview question that was posed to me.
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Akatsukami

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PostPosted: Fri Nov 13, 2015 8:49 pm
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What is meant here by "error"?
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suraaj

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PostPosted: Fri Nov 13, 2015 8:52 pm
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Bad data.
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Akatsukami

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PostPosted: Fri Nov 13, 2015 9:08 pm
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OK, if the data cause the program to abend, it can be found in the dump. Otherwise, you will have to deduce from the erroneous output what the bad data are, and search the data set with some utility. The program should then edits and/or sanity checks added to it so that this situation does not recur.
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RahulG31

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PostPosted: Fri Nov 13, 2015 9:31 pm
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I think this is a vague question.

1. What is a large file? 10000 records or over a million records ?

2. How do you find the error in 'a large file' using debugger ? Do you already know the record in question ?

a. If you don't know the record then do you really plan to go through each record one by one until you find error in 'a large file'?

b. And if you already know the error then why don't you use File mapping utilities like File Aid/ File Manager and see the field having bad data.

3. You can also use displays (depends on how large is the file and If you know the field to display)

.
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RahulG31

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PostPosted: Fri Nov 13, 2015 9:34 pm
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And Why put it in a JCL & VSAM section of the forum ?
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Rohit Umarjikar

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PostPosted: Fri Nov 13, 2015 9:39 pm
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Have you looked at ICETOOL VERIFY?
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suraaj

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PostPosted: Fri Nov 13, 2015 9:58 pm
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Thanks Rohit. This will help me identify decimal values.

Do you know of any other ways which will tell me of bad data?
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Bill Woodger

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PostPosted: Fri Nov 13, 2015 10:01 pm
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"Bad data" can mean anything. Data which must appear on a keyed file/db table can look quite normal, but be "bad" because it does not match.

To find bad data, you have to know what you're looking for.
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suraaj

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PostPosted: Fri Nov 13, 2015 10:06 pm
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You are exactly right Bill. That was the sole reason of me asking for different methods.
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Rohit Umarjikar

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PostPosted: Fri Nov 13, 2015 11:12 pm
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Quote:
Do you know of any other ways which will tell me of bad data?


Suraaj, If any interviewer asks you such questions next time what you should answer is,
a. What do you mean by bad data?
b. Bad data is for numerics, so I told you the way.
c. No one wants to spend time looking just for a bad data in a file unless some jobs abends hence you should ask them about specifics about the abend and the dump.
d.So S0C7 is abend you should see for bad data.

So if you tell this to them then I don't think they will have anymore questions for you on this. They sometimes wants to run some fool tests and we shouldn't get trapped by looking at "Other Methods" which doesn't exist.
Quote:
That was the sole reason of me asking for different methods.

There is no other method than adding display's or look for an offset and investigate.
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Robert Sample

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PostPosted: Fri Nov 13, 2015 11:59 pm
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Quote:
Do you know of any other ways which will tell me of bad data?
I think your basic problem is that "bad data" is ALWAYS context-related. Packed decimal data can cause S0C7 abends but may or may not cause abends.
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suraaj

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PostPosted: Sat Nov 14, 2015 12:43 am
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Thanks Rohit and all others for all your help.
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Pandora-Box

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PostPosted: Sat Nov 14, 2015 12:50 am
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CEEMSG output helps as well in identifying the record in case of S0C7
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