Can neo4j be run in memory only?

[Tu Nguyen]

Hi all,

Is it possible to run Neo4J in memory only without any persistent database/file storage?

I found the answer in the following thread, but it's 3 years ago: http://lists.neo4j.org/pipermail/user/2010-February/002719.html

If Neo4J does not support, please can you suggest any frameworks that support object graph management but do not require data storage on disk.

Thank you in advance.

Tu

[Michael Hunger]

What do you want to do?

Michael

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[Bo Ferri]

Hi,

can this question probably clarified by some neo4j team members? I was also looking for an in-memory version of neo4j to do some graph matching of sub graphs in-memory. At a first glance, I had in mind that the ImpermanentGraphDatabase is in-memory and that this is the appropriated solutation for me (i.e. so that I don't need to re-implement everything for another in-memory graph solution). However, right now (when I had the chance to have a deeper look at ImpermanentGraphDatabase implementation) I have the impression that also the ImpermanentGraphDatabase implementation store its data finally (when cache is full) at the disk, or?

Thanks a lot in advance.

Cheers,


Bo

[Mahmood Shafeie Zargar]

I think Michael's question is still valid here: What do you intend to achieve by using an in-memory graph? Of course if the available memory is limited as compared to the volume of graph data, any in-memory solution will have to resort to some kind of disk-based paging once memory is full. If what you are trying to solve is performance issues, there are ways to make Neo4j keep everything in memory, but that needs ample memory and some customized handling of caching and memory allocation parameters. 

Ref:

http://docs.neo4j.org/chunked/milestone/configuration-caches.html

http://docs.neo4j.org/chunked/stable/configuration-io-examples.html

http://docs.neo4j.org/chunked/stable/configuration-jvm.html

Principally if you make enough memory available to Neo4j, manually set memory map sizes and opt for strong caching you should get the equivalent of an in-memory graph after one traversal over the whole graph. With strong caching Neo4j doesn't ever kick anything out of cash once loaded.

Cheers,

Mah