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vivek1983
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Joined: 20 Apr 2006
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 Posted: Thu Aug 03, 2006 1:43 am Post subject: Complexities in unloading a table |
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Hi,
I have got a requirement to reduce the execution time for a particular batch cycle.
The requirement demands that the queries that are used in the program are well-optimized and hence I am not planning to modify the queries. Instead i am planning to unload the table to a dataset and then use the dataset in the program instead of fetching from the table. Please find my queries below:
1.) Will the performance improve if i access the dataset instead of fetching the table.
2.) Does unload involve any complexities? (My understanding is that unloading from a table means that you are just copying the data from the table to a dataset.)
3.) I am planning to use ADUUMAIN bmc utliity. Is there any performance differences between the BMC utlity and the IBM unload utility ? (DSNTIAUL) ?
Thanks in advance.
Vivek.G |
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shekar123
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Joined: 22 Jul 2005
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Location: Bangalore India
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| Posted: Thu Aug 03, 2006 4:38 am Post subject: |
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vivek1983
I have answers to 1 and 2 .
Yes performance improves if we unload the data to a dataset and then the program read the dataset .Because if in the program you are using cursors to retrive huge volume of data that might end up taking a lot of time to execute.Instead that if you unload and then feed to the program that will be more faster .
Unload has lot of features and it is not complex.Unloading the data from a table means you are copying the data to a dataset.
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Shekar
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kolusu
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| Posted: Thu Aug 03, 2006 8:04 am Post subject: |
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I am planning to use ADUUMAIN bmc utliity. Is there any performance differences between the BMC utlity and the IBM unload utility ? (DSNTIAUL) ?
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vivek1983,
Technically there isn't much difference in execuetion times for both. However BMC utility offers more options when unloading , like creating a delimited files ....
So if your intention is to read the file as the table then there is no difference.
However with Unload of the table, you will be reading a snapshot of the table at that time. If there are any updates to the table after your unload , you will loose that information. If the updates aren't that critical then you can go ahead with unload and read the flat file in the program. So also remember NOT to code the DCB properties on the unload step as DSNTIAUL automatically calculates them. Look at the syspunch dataset from the unload step to see the position of each column in the unload file.
Hope this helps...
Cheers
Kolusu
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vivek1983
Intermediate
Joined: 20 Apr 2006
Posts: 222
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| Posted: Sat Aug 05, 2006 12:23 am Post subject: |
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Thanks kolusu and shekar for your help.
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Vivek G
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A dream is just a dream. A goal is a dream with a plan and a deadline. (Harvey Mackay) |
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