[SPARK-9436] Simplify Pregel by merging joins

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.4.0
• Fix Version/s: 1.5.0
• Component/s: GraphX
• Target Version/s: 1.5.0
• Assignee: Alexander Ulanov
• Reporter: Alexander Ulanov
• Shepherd: Ankur Dave
• Created: 29/Jul/15 13:10
• Updated: 29/Jul/15 21:00
• Resolved: 29/Jul/15 21:00

Description

Pregel code contains two consecutive joins:
```
g.vertices.innerJoin(messages)(vprog)
...
g = g.outerJoinVertices(newVerts)

{ (vid, old, newOpt) => newOpt.getOrElse(old) }

```
They can be replaced by one join. Ankur Dave proposed a patch based on our discussion in mailing list: https://www.mail-archive.com/[e-mail]/msg10316.html

Issue Links

• links to: [Github] Pull Request #7749 (avulanov)