On 1/18/11 13:00 , Mark James wrote:
HI Ivan,
Thanks for the info...
I'm currently considering a multi-tenent system setup where individual
users will 'own' data stored in graphs. I wish to enforce a quota
against each user. But it sounds like I may have to come up with some
other strategy for restricting the amount of data a user can store...
I would probably begin with a combination count of triples and total
size of literal values. Determine a "worst case" scenario per triple
with "somewhat" realistic test data, and adjust by some value derived
no. of triples vs. no of disk pages actually used by the DB.
Yrjänä
Cheers
Mark
On 18 January 2011 19:12, Ivan Mikhailov <[email protected]
<mailto:[email protected]>> wrote:
Hello Mark,
On Sun, 2011-01-16 at 14:21 +1100, Mark James wrote:
> Is there an easy way to determine the amount of disk space an
> individual quad store graph is taking up?
Indexes for IRIs and literals are common for all graphs, so it's not
obvious how to count the consumed space if an IRI is used in more than
one graph.
Accounting for quads becomes unclear too.
Before version 6 it was possible at least to get the size of
indexes for
quads, divide it by total number of quads in all graphs (to get a disk
cost of a single quad) and multiply by number of quads in the
specified
graph, thus some adequate number was available. Starting from
version 6,
there are partial indexes on S,P and O,P, as a part of "3+2" indexing
model, and data of these indexes are shared for all graphs, so not
counting is possible for same reason as for IRIs. In addition, indexes
become bitmaps with compression that can sometimes save significant
amounts of additional data "for free".
So I don't know what to recommend as a reasonable measurement method.
Existing real-life storages may give some hint, but not more,
experiments with synthetic data like benchmarks does not give even a
hint, because they're "too synthetic".
Best Regards,
Ivan Mikhailov
OpenLink Software
http://virtuoso.openlinksw.com
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