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My understanding is that simply removing the logical file member
is enough. With the member removed the access path is gone and
thus not maintained during the load/purge. You don't have to
actually delete the logical.
On the other hand, recreating the logicals in an optimized order
does have benefits....
I wonder if it's possible to automate the
process of rebuilding the logicals in an optimized order...
On Wed, Jun 30, 2010 at 10:27 PM, Evan Harris wrote:
In at least one case dealing with a table of 150+ million rows
I gained significant advantage by deleting the logicals and
recreating them after my processing was done. (At least I think
I gained an advantage - I may have a different view after
posting this)
In this case the logicals had been created as determined by
development requirements (i.e. relatively randomly :) ) which
provided an opportunity to re-create the logicals in a sequence
that took advantage of access path sharing to save space, but
more importantly to improve the speed of recreating the
subsequent access paths (and probably maintenance as well).
I tried to order the creation of the logicals in such a way as
to allow creation of a new logical to leverage already existing
access paths by doing some analysis on the keys of the logicals
- essentially I created from most complex to least complex;
there may have been better ways to do it.
I also dual streamed the creation process so that I had two
logicals being created concurrently and had similar key
structures in the same job path.
Maybe I needn't have actually done re-created the logicals - I
don't know if just removing and adding the member would have
the same effect, but some testing might shed some light on it.
On Wed, Jun 30, 2010 at 3:30 AM, Charles Wilt wrote:
Before I start rolling my own, is anybody aware of a utility
to remove all members from dependent logical files (and SQL
views/indexes) for a given physical that will allow for the
members to be automatically re-added later?
My intent it to purge data from files on our development
machine.
remove logical file members
(optionally) stop journalling
delete records from physical
reorg physical
(optionally) restart journalling
re-add logical file members
I'm thinking that at least the logical file member portion
may also be useful in a bulk data load process..
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