Re: Converting large amount of data

I too have heard that it is best to populate the tables (physical files)
first, then add the logicals.

Some might suggest populating the tables in such a way that they are in
order of the logical you need the best performance from. Or sorting them
afterwards but prior to adding the logicals.
There are obscure little ditties to remember about logicals like adding
them in an order where one can share the access path of another. For
example if you have a logical by ColA, ColB, ColC and one by ColA, ColB
then create the one with all three first.

Where clauses (select/omit in logical file terms) should be first in your
sort order. For example: ActiveRecordCode, ItemNumber.

Rob Berendt
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Sent: Friday, January 22, 2021 11:39 AM
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Subject: Re: Converting large amount of data

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My opinion would be that it would be much more efficient to write the data
and then add your logicals and you want to make sure that you create
indexes first and the logicals so that the indexes are created as SQL
indexes (Larger Page Size).

So you have a logical by company, customer number. First you create an
index by company, customer number and then the logical. The logical will
use the index and then you can delete the index.


On Fri, Jan 22, 2021 at 8:27 AM <smith5646midrange@xxxxxxxxx> wrote:

We have some files that are pretty big that we are going to be converting
to
a new format and I'm looking for some info on converting the data.



I am not looking for answers about splitting in threads or anything like
that. We are converting over 700 files so threads will not help me.
Threads will just delay other files from being converted.



That said, I have one specific question that I am looking for an answer

on.

Is it more efficient to

1. Create the new physical files and their logical files, and then
convert the data

or

2. Create the new physical files, convert the data, and then add the
logical files



I know the machine has 3 CPUs with the ability to pull 3 more from the
pool.

I forget the memory but it is a pretty decent amount

There are 12 I/O channels.



If there is something else you need to know to give me an answer, please
ask.

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