Re: reorg HUGE file

[Evan Harris <spanner@xxxxxxxxxx>]

Funnily enough right now I have to do the same as Dan on a file with 110 
million plus records.

The access path scenario in my experience comes about when programmers 
create a new access path to the file that includes and access path that has 
already been defined. The programs using the old access path never get 
revisited so you still need the new one.

If you rebuild the files correctly you can get the access paths to be 
implicitly shared cutting down the disk space used by the logicals and also 
the re-build time - can be down to practically depending on exactly what is 
shared.

Be aware that there are a few access wrinkles to do with implicitly shared 
access paths, I think the data management manual highlights them. 
Basically, depending on how you use keys to position once you are using the 
implictly shared access paths under some circumstances your 
read/positioning logic may behave differently depending on how you 
implement it.

I would caution you to show this to the developers (who in my experience 
didn't look at it)

Since the system will cause this to happen in the event of a restore 
anyway, you have a valid rebuttal for the programmers when they ask you not 
to do this - presuming its a problem or just something they don't want to 
deal with.

Hope this helps
Evan Harris

>Stupid question, I know, but why have L6, L8 or L2 at all?
>
>---------
>Noticing that L6 could use the access path of L8, and L8 could use the access
>path of L3, and L2 could use the access path of any of the other listed
>logicals, does the system recognize this and build L3 before L8, L8 before L6,
>and build L2 last?  (What's the term that describes a logical file using the
>access path of another?)  Or do key duplicates follow FIFO by default?  How do
>I tell?
>
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