Big Flat Stacks - NULLs

Phil Davis revdev at pdslabs.net
Thu Jun 17 00:51:45 CDT 2010


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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