Re: reorg HUGE file -- MIDRANGE-L

At 07:47 PM 2/26/01 -0500, you wrote:
 >I've got a file with 40 million records, 10 million of which are 
deleted.  The
 >file is over 14 GB.  There are 8 access paths built on this file.  We would
 >like to attempt a reorg of this file, but are concerned about the downtime
 >we'll experience as this file is used throughout our operations.  Is 
there any
 >reliable way to estimate the time required to reorg?


There is no way to estimate.  REUSEDLT (Re-use deleted records) is a good
solution if you have NO programs that read the file sequentially and count
on the fact that the records are in sequential order by date/time
generated.  This is difficult to determine unless it is all your own code.

Lakeview sells a product that does a re-org while in use.  It requires
journaling.


 >FWIW, this is a model 510 running V3R7 and it has 94 GB of DASD, of which 76%
 >is currently being used, and 392 MB of memory.


Relatively tiny system now-a-days.


 >If I did a RGZPFM, I'd remove the members from the file's logicals before the
 >reorg, and then add them back after.  I think I've heard it would be more
 >efficient to do so.


If and only if some of the access paths build off each other.  Clearly this
will have positive performance implications if you have any multi-record
format logicals, or LF joins.  Particularly beneficial if you have multiple
files to re-org.


 >Should I also consider duplicating the physical file in a separate 
library and
 >using CPYF to copy the 30 million records into it, then duplicate the 
logicals
 >over, then delete the original library's files, then move the newly copied
 >data over?

This is essentially what happens under the covers.

Internal sequence is:

all access paths are removed  (includes keyed physical and LFs)
file is copies to a "hidden space" omitting deleted records
file is moved back, with out a change of create date, etc.
all access paths are rebuild

Al




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Al Barsa, Jr. - Account for Midrange-L
Barsa Consulting, LLC.  
400 > 390

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