MOO-cows Mailing List Archive


Re: Do clear properties take up space in the DB.

On Sun, 22 Dec 1996, Francis Litterio wrote:

> I'm considering adding a new property to #1 which will be clear on
> nearly every object in the DB except a very few.  Will doing so bloat my
> DB (in memory and on disk) by much?  I guess I'm wondering whether
> having a property on every object that is clear 99.99% of the time will
> take up much space (compared to not having that property at all).

Standard disclaimers apply:

Well, AFAIK, it'll add ~16[1] bytes (memory) to the size of every
descendant of #1, even if that property is clear on those objects.  This
is the cost of creating a struct Pval for that property on the
descendants, which stores value, ownership and permission info for the
property on each object.  If the property is clear on an object, then a
special (type) value is stored in the value part. 

I'm not so sure about space used on disk.  I'd guess that information is 
stored for clear properties there, too, but the space required isn't so 
clear because it's text. ;)

[1] 14 is probably about the minimum you can expect, it's increased to 16
to keep things aligned nicely on the machine I'm running on.


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