Managing Distributed Projections

Overview

A distributed projection resides in the memory of the corresponding shard servers where the data is persistently stored. It can hold either full or partial data from a graph. The term "distributed projection" indicates that data within it can be distributed across the memory of multiple shards.

NOTE

All distributed projections of a graph are lost when the data in the graph is migrated to different shards.

Showing Distributed Projections

Retrieves information about all distributed projections of the current graph:


SHOW PROJECTION

It returns a table _projectionList with the following fields:

Field	Description
`name`	Name of the projection.
`graph_name`	Name of the current graphset from which the data was loaded.
`status`	Current state of the projection, which can be `DONE` or `CREATING`, `FAILED` or `UNKNOWN`.
`stats`	Node and edge statistics per shard, including `address` of the leader replica of the current graphset, `edge_in_count`, `edge_out_count` and `node_count`.
`config`	Configurations for the distributed projection.

Creating a Distributed Projection

The projection creation is executed as a job, you may run SHOW JOB <id?> (GQL) or show().job(<id?>) (UQL) afterward to verify the success of the creation.

Syntax


CREATE PROJECTION <projectionName> OPTIONS {
  nodes: {
    "<schema1>": ["<property1>", "<property2>", ...],
    "<schema2>": ["<property1>", "<property2>", ...],
    ...
  },
  edges: {
    "<schema1>": ["<property1>", "<property2>", ...],
    "<schema2>": ["<property1>", "<property2>", ...],
    ...
  },
  direction: "<edgeDirection>",
  load_id: <boolean>
}

Param	Description	Optional
`<projectionName>`	Name of the projection. Projections of the same graph cannot have duplicate names. Projections and HDC graphs of the same graph cannot have duplicate names.	No
`nodes`	Specifies nodes to project based on schemas and properties. The `_uuid` is loaded by default, while `_id` is configurable with `load_id`. Sets to `"": [""]` to load all nodes.	Yes
`edges`	Specifies edges to project based on schemas and properties. All system properties are loaded by default. Sets to `"": [""]` to load all edges.	Yes
`direction`	Since each edge is physically stored twice - as an incoming edge along its destination node and an outgoing edge with its source node - you can choose to project only incoming edges with `in`, only outgoing edges with `out`, or both with `undirected` (the default setting). Please note that `in` or `out` restricts graph traversal during computation to the specified direction.	No
`load_id`	Sets to `false` to project nodes without `_id` values to save the memory space; it defaults to `true`.	Yes

Examples

To project the entire current graphset to its shard servers as distGraph:


CREATE PROJECTION distGraph OPTIONS {
  nodes: {"*": ["*"]}, 
  edges: {"*": ["*"]},
  direction: "undirected",
  load_id: true
}

To project account and movie nodes with selected properties and incoming rate edges in the current graph to its shard servers as distGraph_1, while omitting nodes' _id values:


CREATE PROJECTION distGraph_1 OPTIONS {
  nodes: {
    "account": ["name", "gender"],
    "movie": ["name", "year"]
  },
  edges: {"rate": ["*"]},
  direction: "in",
  load_id: false
}

Dropping a Distributed Projection

Deletes the distributed projection named distGraph_1:


DROP PROJECTION distGraph_1