> > A value record would essentially be an array of bytes as defined in
> > Value.getStream(). In other words the integer value 123 and the string
> > value "123" would both be stored in the same value record. More
> > specific typing information would be indicated in the property record
> > that refers to that value. For example an integer property and a
> > string property could both point to the same value record, but have
> > different property types that indicate the default interpretation of
> > the value.
> i think that with small values we have to keep in mind that the
> "key" (value identifier) may be bigger than the actual value and of
> course the additional indirection also has a performance impact.
> do you think that we should consider a minimum size for value's to
> key stored in this manner? personally, i think that this might make
> sense.
For consistency I would use such value records for all values,
regardless of the value size. I'd like to keep the value identifiers
as short as possible, optimally just 64 bits, to avoid too much
storage and bandwidth overhead. The indirection costs could probably
best be avoided by storing copies of short value contents along with
the value identifiers where the values are referenced.
> anyway, what key did you have in mind?
> i would assume some sort of a hash (md5) could be great or is this
> still more abstract?
I was thinking about something more concrete, like a direct disk
offset. The value identifier could for example be a 64 bit integer
with the first 32 bits identifying the revision that contains the
value and the last 32 bits being the offset of the value record within
a "value file". I haven't yet calculated whether such a scheme gives
us a large enough identifier space.
i would use MD5 of the contents as keys...so your search for
dublicates is very cheep. and i would not use a value record for small
values. eg; the overhead of storing a 'boolean' is just too big.
considering you have 1mio nodes, with every node having a
'isCheckechedOut' property.... or a lastModified, whitch is never the
same.
regard, toby
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Tobias Bocanegra, Day Management AG, Barfuesserplatz 6, CH - 4001 Basel
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