HP3000-L Archives

March 1996, Week 2

HP3000-L@RAVEN.UTC.EDU

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From:
Gilles Schipper <[log in to unmask]>
Reply To:
Gilles Schipper <[log in to unmask]>
Date:
Wed, 13 Mar 1996 14:54:11 -0500
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Tom Stelter wrote:
>Possibly what is meant by Lee's statement is that any time you make a
>capacity change on an Image Master, physical placement of entries changes
>based on hashing, secondaries, migrating secondaries(takes long time on
>large masters).  Since Image Logging is dependent on physical entry number
>only, any physical movement of entries causes an Image 'Log logid,Restart'
>to be inapplicable since DBRECOV depends on enrty number, not key values,
>etc.  Certain database tools will require you to stop logging if you make
>master capacity changes, but will not require you to stop logging on an
>detail since the cap change(no repacking)does nothing more than add space at
>the end of the dataset(for cap increase and decreases as long as you don't
>collapse smaller than the high water mark).
 
I believe that Image logging is NOT dependent on physical entry number - and
that is precisely why I suggested your logging cycle should not require
resetting in the event of capacity changes - subject to the caveats I described.
 
I'm sure others will correct me if I'm wrong.

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