Daniel Kuppitz created TINKERPOP-1609:
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Summary: Make store() support maps
Key: TINKERPOP-1609
URL: https://issues.apache.org/jira/browse/TINKERPOP-1609
Project: TinkerPop
Issue Type: New Feature
Components: process
Affects Versions: 3.2.3
Reporter: Daniel Kuppitz
Let me start with an example. This is the betweeness centrality algorithm from
our recipes docs:
{noformat}
g.V().as("v").
repeat(both().simplePath().as("v")).emit().
filter(project("x","y","z").by(select(first, "v")).
by(select(last, "v")).
by(select(all, "v").count(local)).as("triple").
coalesce(select("x","y").as("a").
select("triples").unfold().as("t").
select("x","y").where(eq("a")).
select("t"),
store("triples")).
select("z").as("length").
select("triple").select("z").where(eq("length"))).
select(all, "v").unfold().
groupCount().next()
{noformat}
One compute intensive part of the unrolling of previously seen triples to see
if a shortest path between a specific pair of vertices was already found. It
would be smarter to store the vertex pair in a map (the key being the pair and
value being the path length). For that reason I suggest that we make `store()`
support maps by allowing more than one {{by()}} modulator. Furthermore we need
the ability to select dynamic map keys, but that's another ticket. For this
ticket focus on {{store()}} and ignore the nested {{select()}}in the following
rewritten example:
{noformat}
g.V().as("v").
repeat(both().simplePath().as("v")).emit().
filter(project("x","y","z").by(select(first, "v")).
by(select(last, "v")).
by(select(all, "v").count(local)).as("triple").
coalesce(select("m").select(select("x","y")),
store("m").by(select("x","y")).
by(select("z")).select("z")).as("length")
select("triple").select("z").where(eq("length"))).
select(all, "v").unfold().
groupCount().next()
{noformat}
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