Big Flat Stacks - NULLs

Michael Kann mikekann at yahoo.com
Thu Jun 17 08:09:44 CDT 2010


Phil,

What ASCII number is a NULL?

Mike

--- On Thu, 6/17/10, Phil Davis <revdev at pdslabs.net> wrote:

> From: Phil Davis <revdev at pdslabs.net>
> Subject: Re: Big Flat Stacks - NULLs
> To: "How to use Revolution" <use-revolution at lists.runrev.com>
> Date: Thursday, June 17, 2010, 12:51 AM
> On 6/16/10 8:27 PM, Paul Looney
> wrote:
> > Jacque,
> > Thanks for the excellent explanation.
> > So far we have imported over a thousand HC stacks into
> our Rev-based business system. These are mostly databases
> from our customers.
> > We noticed that, with some customers, up to a third of
> the archived orders did not make it into the new system.
> When checking further, we found these were customers who
> regularly pasted text from MS Word or AppleWorks into one of
> the Notes fields. Incidentally, removing the NULLs before
> import was not always successful, either.
> > Another NULL problem in Rev has been sorts. We've
> found that information is often missing when sorting data
> containing NULLs (on one occasion, the pre-sort data was two
> megabytes larger than the post-sort). Removing NULLS from
> the data before sorting (which we always do now) has fixed
> the problem for us.
> > Paul Looney
> 
> The "filter" command can also malfunction if the data
> contains nulls. I ran into that this week.
> 
> Phil Davis
> 
> > 
> > On 16/06/2010, at 7:21 PM, J. Landman Gay wrote:
> > 
> >> Bob Sneidar wrote:
> >>> I vaguely recall that HC was not supposed to
> have nulls, but some bug
> >>> or other caused them and wrecked havoc with HC
> stacks. Compacting the
> >>> stack seemed to eliminate them.
> >> 
> >> HC used nulls as end-of-field markers, so if text
> containing nulls was pasted into an HC field, the text would
> truncate at the first null. I once had to debug a stack like
> that, where someone had pasted some text from AppleWorks
> into the stack. It wasn't a bug, just a result of pasting.
> >> 
> >> Rev handles nulls in fields fine. But during a
> normal Rev import, the Rev engine knows that nulls were
> end-of-field markers in HC and so probably truncates the
> incoming text at that point too, just as HC did.
> >> 
> >> I'm not sure why Paul would need to replace
> incoming nulls with empty though, since the Rev engine
> shouldn't bring any of them in when it opens a HC stack.
> >> 
> >> -- Jacqueline Landman Gay     
>    |     jacque at hyperactivesw.com
> >> HyperActive Software       
>    |     http://www.hyperactivesw.com
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> 
> -- Phil Davis
> 
> PDS Labs
> Professional Software Development
> http://pdslabs.net
> 
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