[Neo] how does nioneo store nodes and relationships

Johan Svensson johan at neotechnology.com
Sun Mar 29 19:30:01 CEST 2009


Hi,

There is currently no good documentation or explanation on Nioneo. I
would suggest you have a look at the code in
org.neo4j.impl.nioneo.store.

We used fixed size records to store nodes and relationships (see
NodeStore and RelationshipStore). Relationships are stored in a
"interleaved double linked list".  Each store may have memory mapped
regions (depending on configuration and request patterns) with a fall
back on direct buffers.

The store files are only flushed when logical log needs to rotate
making it easier for the OS and file system in place to perform disk
I/O optimizations.

-Johan

On Sun, Mar 29, 2009 at 12:00 PM, afterstep 13 <afterstep13 at gmail.com> wrote:
> I am trying to understand how nioneo stores nodes and relationships on the
> disk.
>
> How does nioneo organize nodes and relationship in these files. (algos and
> data-structures)
> How does it optimize disk io


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