arangodb/arangod/Pregel

Pregel Subsystem

The pregel subsystem implements a variety of different grapg algorithms, this readme is more intended for internal use.

Protocol

Message format between DBServers:

{sender:"someid", executionNumber:1337, globalSuperstep:123, messages: [, , vertexID2, ] } Any type of slice is supported

Useful Commands

Import graph e.g. https://github.com/arangodb/example-datasets/tree/master/Graphs/1000 First rename the columns '_key', '_from', '_to' arangoimp will keep those.

In arangosh:

db._create('vertices', {numberOfShards: 2});
db._createEdgeCollection('alt_edges');
db._createEdgeCollection('edges', {numberOfShards: 2, shardKeys:["_vertex"], distributeShardsLike:'vertices'});

arangoimp --file generated_vertices.csv --type csv --collection vertices --overwrite true --server.endpoint http+tcp://127.0.0.1:8530

Or: for(var i=0; i < 5000; i++) db.vertices.save({_key:i+""});

arangoimp --file generated_edges.csv --type csv --collection alt_edges --overwrite true --from-collection-prefix "vertices" --to-collection-prefix "vertices" --convert false --server.endpoint http+tcp://127.0.0.1:8530

AQL script to copy edge collection into one with '_vertex':

FOR doc IN alt_edges INSERT {_vertex:SUBSTRING(doc._from,FIND_FIRST(doc._from,"/")+1), _from:doc._from, _to:doc._to} IN edges LET values = ( FOR s IN vertices RETURN s.result ) RETURN SUM(values)

AWK Scripts

Make CSV file with ID’s unique cat edges.csv | tr '[:space:]' '[\n*]' | grep -v "^\s*$" | awk '!seen[$0]++' > vertices.csv

Make CSV file with arango compatible edges

cat edges.csv | awk -F" " '{print "profiles/" $1 "\tprofiles/" $2 "\t" $1}' >> arango-edges.csv

arangoimp --file vertices.csv --type csv --collection twitter_v --overwrite true --convert false --server.endpoint http+tcp://127.0.0.1:8530 -c none arangoimp --file arango-edges.csv --type csv --collection twitter_e --overwrite true --convert false --separator "\t" --server.endpoint http+tcp://127.0.0.1:8530 -c none