graph

Overview ¶

Package graph contains the main API to the graph datastore.

Manager API ¶

The main API is provided by a Manager object which can be created with the NewGraphManager() constructor function. The manager CRUD functionality for nodes and edges through store, fetch and remove functions. It also provides the basic traversal functionality which allos the traversal from one node to other nodes.

Node iterator ¶

All available node keys in a partition of a given kind can be iterated by using a NodeKeyIterator. The manager can produce these with the NodeKeyIterator() function.

Fulltext search ¶

All nodes and edges in the datastore are indexed. The index can be queried using a IndexQuery object. The manager can produce these with the NodeIndexQuery() or EdgeIndexQuery function.

Transactions ¶

A transaction is used to build up multiple store and delete tasks for the graph database. Nothing is written to the database before calling commit(). A transaction commit does an automatic rollback if an error occurs (except fatal disk write errors which might cause a panic).

A trans object can be created with the NewGraphTrans() function.

Rules ¶

(Use with caution)

Graph rules provide automatic operations which help to keep the graph consistent. Rules trigger on global graph events. The rules SystemRuleDeleteNodeEdges and SystemRuleUpdateNodeStats are automatically loaded when a new Manager is created. See the code for further details.

Graph databases ¶

A graph manager handles the graph storage and provides the API for the graph database. The storage is divided into several databases:

Main database ¶

MainDB stores various meta information such as known node/edge kinds, attributes or version information.

Names database ¶

Names can be encoded (into a number) or decoded (into a string)

32 bit values for any given node attribute names
16 bit values for any given edge role names
16 bit values for any given edge kind names

Nodes database ¶

Each node kind database stores:

PrefixNSAttrs + node key -> [ ATTRS ]
(a list of attributes of a certain node)

PrefixNSAttr + node key + attr num -> value
(attribute value of a certain node)

PrefixNSSpecs + node key -> map[spec]<empty string>
(a lookup for available specs for a certain node)

PrefixNSEdge + node key + spec -> map[edge key]edgeinfo{other node key, other node kind}]
(connection from one node to another via a spec)

Edges database ¶

Each edge kind database stores:

PrefixNSAttrs + edge key -> [ ATTRS ]
(a list of attributes of a certain edge)

PrefixNSAttr + edge key + attr num -> value
(attribute value of a certain edge)

Index database ¶

The text index managed by util/indexmanager.go. IndexQuery provides access to the full text search index.