Scott Kane wrote:
I think I'll look at saving stacks containing
cards to an external file instead.
For very small data sets it's hard to beat the convenience of using
cards. But for anything above a few thousand records it can be cumbersome.
As with HyperCard, the inventor of this engine (Scott Raney) reminds us
that the stack structure is not optimized for use as a database. Dr.
Raney suggests that you'll find serious performance degredation after
about 5,000 records, and in my experience I find that to be true.
So if you need fewer than a couple thousand records then using cards may
be a great option. But if you'll need more it may be useful to consider
lists or custom properties.
To help you get an idea of the performance differences between these, I
threw together a script that creates 5,000 records in each format,
copied below. To run it:
1. Make a new stack
2. Make some fields (I used 7), group them,
and turn on the group's backgroundBehavior
3. Paste the script below into a field
Here are the results (1GHz PowerBook, OS X 10.4, 768MB RAM):
Cards: 50860ms List: 168ms Props: 236ms
Saving the data shows a similar disparity of performance: stacks with
large numbers of cards take an increasingly long time to save as the
number of cards grows, disproportionate to the actual number of cards
(not quite geometric, but certainly not linear). But saving a stack
file with one card and thousands of properties is very fast.
--
Richard Gaskin
Managing Editor, revJournal
_______________________________________________________
Rev tips, tutorials and more: http://www.revJournal.com
--------------------------------------------------------
on mouseUp
put 5000 into n
--
-- Cards:
lock messages
lock screen
put the millisecs into t
repeat n
create cd
repeat with i = 1 to the number of flds
put "dsgsdtg sdtg dwg dsg sdgsdg" into fld i
end repeat
end repeat
put the millisecs - t into t1
--
-- List:
global gData
put empty into gData
put the millisecs into t
repeat n
put empty into tRecord
repeat the number of flds
put "dsgsdtg sdtg dwg dsg sdgsdg" &tab after tRecord
end repeat
put tRecord &cr after gData
end repeat
delete last char of gData
put the millisecs - t into t2
--
-- Props:
set the customproperties of this stack to empty
put the millisecs into t
repeat with i = 1 to n
put empty into tRecord
repeat the number of flds
put "dsgsdtg sdtg dwg dsg sdgsdg" &tab after tRecord
end repeat
set the uMyData[i] of this stack to tRecord
end repeat
put the millisecs - t into t3
--
put "Cards: "& t1 &"ms List: "&t2&"ms Props: "& t3 &"ms"
end mouseUp
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