RE: File Reorg - Cons -- MIDRANGE-L

Hi Mike

just to give you even more to think about :)

I was once lucky enough to have a 140 million record monster file with a 700+ character record length and 25 logicals built over it that had 20 million plus deleted records which had to be re-organised. (makes me sound like a Yorkshire man seeing it written down like that...)

In any case, if time is at a premium some of the things I found that can help a great deal are to:

- Drop the logical files before doing the re-org then manually create them afterwards

- You can run two or more rebuilds through submitting CRTLF commands to run concurrently; normally RGZPFM seemed to/used just build them in an arbitrary order I could never figure out but looked to be original creation order.

- It is possible to somewhat optimise the rebuild sequence which may save disk and will almost certainly save time. Analyze the keys on your logical files to determine which have the most complex keys or keys that can be used to assist in building subsequent access paths (some experimentation may be in order here). If you optimise the order from most complex to least complex and arrange them in job streams appropriate for the keys (e.g. one job stream for customer number/etc keys, another for customer name/etc keys) you may save some time.

- If you are really cramped for time write a program to write the records out to a new file. This also provides the option to run parallel job streams of the read/write operations by selecting records to be added into the file to be replaced by relative record number ranges. When the writes have completed delete the old file (if you dare :) and rename the new as the old and start building your indexes. This can significantly speed things up :)

Hope this helps

Regards
Evan Harris

> On Behalf Of Mike Berman
> Subject: File Reorg - Cons
>
> I noted alot of suspicion when I attempted to set up a file reorg process.
> Just getting lists of those with large amounts of deleted records. Is
> there some possible occurance that would be a detriment? I am of course
> referring to off hours running.

This mailing list archive is Copyright 1997-2024 by midrange.com and David Gibbs as a compilation work. Use of the archive is restricted to research of a business or technical nature. Any other uses are prohibited. Full details are available on our policy page. If you have questions about this, please contact [javascript protected email address].

Operating expenses for this site are earned using the Amazon Associate program and Google Adsense.