Today, I tried to migrate my application from Neo4j 1.3 to 1.4M03 and ran into
problems with respect to the in-graph Timeline index in the legacy component
Neo4j-index.
For all Lucene related indexing, I have moved to greener pastures and use the
new indexing framework, but for several indexing needs only an in-graph index
is suitable.
Examples:1) Most of the nodes in my application have versioning enabled. To do
so, I maintain a in-graph Timeline index containing "version nodes". The
Timeline index is needed to maintain order and to register a timestamp for each
version.
2) Most of the nodes in my application are related to a context. Every user or
user group maintains two or more contexts. The relationship between node and
context is again stored in the Timeline index, to make it possible to retrieve
the most recent additions for a user or user group.
Both scenarios can potentially create a huge number of indexes, most of them
relatively small, but some become large enough that in-memory sorting is not an
option.
The in-graph Timeline index offers the right functionality for these scenarios
and the Lucene index service is not a feasible replacement in these cases.
The in-graph Timeline index is now fixed to version Neo4j 1.3, and given the
legacy Lucene code in that component will not likely be upgraded to version
1.4.
Using Neo4j-index 1.3-SNAPSHOT with Neo4j 1.4M03 is not possible without
hacking the POM (which I have done, but don't feel too happy about).
Neo4j-index 1.3-SNAPSHOT requires Lucene 3.0.1, while Neo4j 1.4M03 requires
Lucene 3.1.0, leading to version conflicts in projects.
Approximately a month ago, I made the suggestion (see:
http://lists.neo4j.org/pipermail/user/2011-May/008461.html) to move the
in-graph Btree index and its related classes (including Timeline) to a new
component Neo4j-collections, while keeping the old Lucene index stuff in
Neo4j-index, so it can eventually become deprecated.
I hope my suggestion will be taken into consideration.
Kind regards,Niels Hoogeveen
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