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Inserting new records and how they then display in File Mana


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Div Grad

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Joined: 08 Apr 2005
Posts: 45

PostPosted: Fri Oct 03, 2014 1:19 am
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I used a SPUFI to insert approx. 10,000 rows into a million row table. Then I used File Manager For z/OS (DB2) to eyeball my results. Everything looked good and then I slowly realized that my inserted records were always 21 rows apart as displayed.

I found that disconcerting because my belief is that the records come up sorted by key(s). So why would they be evenly spaced like that when I know the new keys are random? Looking closer I noticed that while all the old rows were coming up sorted on key(s) the new records I inserted were coming up as every 21st record within the old correctly sorted records. If I did an explicit sort on the keys then the new records were randomly spaced as expected.

So what is going on here, something analogous to blocking with flat files? I'm expecting a reorg overnight will eliminate this phenomenon.
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Rohit Umarjikar

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Joined: 21 Sep 2010
Posts: 2588
Location: NYC,USA

PostPosted: Fri Oct 03, 2014 1:52 am
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Div, What happens when you do a select query in a SPUFI by desc order with the keys and limit the result to may be 10k? if you did so then are you getting the same results as above?
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daveporcelan

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Joined: 01 Dec 2006
Posts: 754
Location: Pennsylvania

PostPosted: Fri Oct 03, 2014 5:30 pm
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Unless you do an explicit order by, what you 'see' is irrelevant in every way.

They way DB2 stores the data does not matter.

They way you see the data does not matter.

You may see something different after the reorg, you may not.

You may see something different after additional records are added or deleted, you may not.

Without an order by, the results are unpredictable. Period.
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GuyC

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Joined: 11 Aug 2009
Posts: 1281
Location: Belgium

PostPosted: Fri Oct 03, 2014 7:12 pm
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If you really want to know , read about pctfree and freepage
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