[Opensim-dev] Please do not revert fixes without careful comtemplation

[Frisby, Adam]

You do realise you could just not update the asset. If the hash is the same, then you can just completely ignore the save/update request.

That being said, even a targeted collision on MD5 is a 2^58 chance, on SHA256 it's well over 2^128 which makes it pretty much impossible. Frankly it's not something worth concerning oneself over.

Adam

> -----Original Message-----
> From: opensim-dev-bounces at lists.berlios.de [mailto:opensim-dev-
> bounces at lists.berlios.de] On Behalf Of Melanie
> Sent: Monday, 16 February 2009 4:45 AM
> To: opensim-dev at lists.berlios.de
> Subject: Re: [Opensim-dev] Please do not revert fixes without careful
> comtemplation
>
> Again, I'd like to stress that I believe this is too dangerous to do
> for anything other than textures.
> It is also not really needed for things other than textures, since
> the other assets are comparatively small, textural data.
>
> I would not want to risk even the smallest chance of a hash
> collision on script source.
>
> Melanie
>
> Stefan Andersson wrote:
> > Coming in a bit from the side here,
> >
> >
> >
> > we have, for some time, discussed to separate out the binary blog out
> of the metadata for an entirely different reason, namely to be able to
> weed out binary duplicates.
> >
> >
> > If there was a way for us to separate out the binary parts, into
> something like 'binaryassetId, hashData[256], binarydata' and then just
> have the asset table referencing that row, I think it would help a lot.
> >
> >
> > I realize it's a separate discussion, just chipping in my two cents.
> >
> >
> > Best regards,
> > Stefan Andersson
> > Tribal Media AB
> >
> >
> >
> >
> >
> >
> > Date: Sat, 14 Feb 2009 17:49:22 +0200
> > From: tommi.s.e.laukkanen at gmail.com
> > To: mmazur at gmail.com
> > CC: opensim-dev at lists.berlios.de
> > Subject: Re: [Opensim-dev] Please do not revert fixes without careful
> comtemplation
> >
> >
> > Hello,
> >
> > On second though we could keep the current structure and expose all
> fields also through AssetBase properties. Then we could save / load the
> AssetBase with nhibernate as a single object and leave out the Metadata
> property from NHibernate mapping. Does this sound good?
> >
> > regards,
> > Tommi
> >
> >
> > On Sat, Feb 14, 2009 at 5:06 PM, Mike Mazur <mmazur at gmail.com> wrote:
> >
> > Hi,
> >
> > On Sat, Feb 14, 2009 at 4:05 PM, Tommi Laukkanen
> >
> > <tommi.s.e.laukkanen at gmail.com> wrote:
> >
> >> I was talking with mikkopa and he suggested we should create two
> tables to
> >> cover AssetBase to solve this issue properly. Namely AssetMetadata
> for
> >> metadata information and AssetData for blobs to avoid situation
> where we end
> >> up accessing also the blob data just to read metadata.
> >
> > I was hoping not to have to do that.
> >
> > It should be straightforward to support the current
> > AssetBase/AssetMetadata composition in the existing OpenSim data
> > layers, but as sdague warned me earlier, by mapping multiple classes
> > to one table I was entering a world of pain. Seems that's exactly
> > what's happening with NHibernate.
> >
> > The reason I introduced the AssetMetadata class is to supply metadata
> > information only for some requests that Cable Beach, the new asset
> > server, supports. Now I realize that this was probably a premature
> > optimization.
> >
> > Instead of modifying the DB schema, we could have AssetBase inherit
> > from AssetMetadata, as I outlined before[1]. Alternatively, we could
> > get rid of AssetMetadata altogether and store everything in AssetBase
> > as before, splitting out the metadata sometime in the future when a
> > use case warrants it.
> >
> > What do you think?
> >
> > Thanks,
> > Mike
> >
> >
> > [1] https://lists.berlios.de/pipermail/opensim-dev/2009-
> February/004918.html
> >
> >
> >
> >
> > ---------------------------------------------------------------------
> ---
> >
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