What I need to store in an index depends on the type of element that needs to
be reified.
Relatationship:
To associated Node: RelId -> NodeIdFrom associated Node: NodeId -> RelId
RelationshipType:
To associated Node: RelationhipType.name -> NodeIdFrom associated Node: NodeId
-> RelationshipType.name;
RelationshipRole:To associated Node: RelationhipRole.name -> NodeIdFrom
associated Node: NodeId -> RelationshipRole.name;
PropertyType:To associated Node: PropertyType.name -> NodeIdFrom associated
Node: NodeId -> PropertyType.name;
Property:To associated Node: Node, PropertyType.name -> NodeIdFrom associated
Node: NodeId -> Node, PropertyType.name
Niels
> Date: Fri, 29 Jul 2011 06:49:31 +0200
> From: [email protected]
> To: [email protected]
> Subject: Re: [Neo4j] bdb-index
>
> Hi xD
> I'm not clear what you need to store here, if I understand correctly you
> could store in 2 primary bdb databases the nodeID (ie. long) of each node in
> a relationship
> ie.
> key->value
>
> dbForward:
> A->B
> A->C
> X->D
> X->B
>
> dbBackward:
> B->A
> B->X
> C->A
> D->X
>
> A,B,C,D,X are all nodeIDs ie. longs
>
> this way you could check if A->B exists, or all of A's endNodes , or what
> startNodes are "pointing" to the endNode B
> the storing of these would be sorted and in BTree, lookup would be fast, so
> you can consider ie. A as being a set of B and C, and X being a set of B and
> D, (that is you cannot set the order as in a list, they are sorted by bdb
> for fast retrievals). (But upon this, sets, can build lists np - that is
> using only bdb; tho you won't need that using neo4j)
> So, if this is the kind of index you wanted... (I am not aware of specific
> indexes with bdb, though that doesn't mean they don't exist)
>
> Insertions would require transaction protection so both A->B in dbForward
> and B->A in dbBackward are inserted atomically. Parsing A then X of B-> in
> dbBackward for example can only be done with a cursor...
>
> Either way, I'm taking a look on that bdb-index thingy; will report back if
> I have any ideas heh
>
> John.
>
> On Thu, Jul 28, 2011 at 9:42 PM, Niels Hoogeveen
> <[email protected]>wrote:
>
> >
> > Thank you, Peter,There is no rush here. It would be nice to investigate
> > this option, but it can wait until Mattias has returned and sifted through
> > urgent matters. The question is even, if it would be a good idea to use an
> > index to do the book keeping for Enhanced API.As it is now, the Reification
> > of eg. a Relationship, requires one property to be set on a relationship,
> > containing the node ID of the associated node. On the associated node is a
> > property containing the ID of the relationship, so there is a bidirectional
> > look up. Introducing an index would remove the need to have these additional
> > properties, but would lead to slower look-up times (no matter how fast the
> > index).So it's a trade-off between speed and cleanliness of namespace. Using
> > the Enhanced API disallows certain property names to be used in user
> > applications.The property names used in Enhanced API all start with
> > "org.neo4j.collections.graphbd.", so there is little chance a user
> > application would want to use those property names, but it is a restriction
> > not found in the standard API, so ultimately something to consider.Niels
> > > From: [email protected]
> > > Date: Thu, 28 Jul 2011 10:39:47 -0700
> > > To: [email protected]
> > > Subject: Re: [Neo4j] bdb-index
> > >
> > > niels,
> > > in this spike, I just concentrated on getting _something_ working in
> > > order to test insertion speed. This is not up to real indexing
> > > standards, so some love is needed here. I think Mattias is the best
> > > person to ask about pointers, let's wait until he is back next week if
> > > that is ok? Maybe some other (like the standard Lucene) index can
> > > suffice for the time being to test out things?
> > >
> > > Cheers,
> > >
> > > /peter neubauer
> > >
> > > GTalk: neubauer.peter
> > > Skype peter.neubauer
> > > Phone +46 704 106975
> > > LinkedIn http://www.linkedin.com/in/neubauer
> > > Twitter http://twitter.com/peterneubauer
> > >
> > > http://www.neo4j.org - Your high performance graph
> > database.
> > > http://startupbootcamp.org/ - Öresund - Innovation happens HERE.
> > > http://www.thoughtmade.com - Scandinavia's coolest Bring-a-Thing party.
> > >
> > >
> > >
> > > On Thu, Jul 28, 2011 at 10:36 AM, Niels Hoogeveen
> > > <[email protected]> wrote:
> > > >
> > > > Trying to find something useful to hide the implementation book keeping
> > of Enhanced API, I tried out dbd-index as can be found here:
> > https://github.com/peterneubauer/bdb-index
> > > > It looks interesting, but fails its tests. When recovering it performs
> > BerkeleyDbCommand#readCommand from the log. The retrieved indexName is not
> > actually garbage. I would like to help make this component workable, but
> > area of the database is a bit beyond the scope that I know.
> > > > I know this is completely unsupported software, but can someone give me
> > some pointers on how to fix this issue?
> > > > Niels
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