[MADLIB-1229] Duplicated result in PageRank output table with grouping

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: v1.15
• Component/s: Module: Graph
• Assignee: Himanshu Pandey
• Reporter: Jingyi Mei
• Created: 12/Apr/18 01:06
• Updated: 17/Jul/18 22:13
• Resolved: 17/Jul/18 22:00

Description

In madlib 1.13, if I run the follow query

DROP TABLE IF EXISTS vertex, "EDGE";
CREATE TABLE vertex(
id INTEGER
);
CREATE TABLE "EDGE"(
src INTEGER,
dest INTEGER,
user_id INTEGER
);
INSERT INTO vertex VALUES
(0),
(1),
(2);
INSERT INTO "EDGE" VALUES
(0, 1, 1),
(0, 2, 1),
(1, 2, 1),
(2, 1, 1),
(0, 1, 2);


DROP TABLE IF EXISTS pagerank_ppr_grp_out;
DROP TABLE IF EXISTS pagerank_ppr_grp_out_summary;
SELECT pagerank(
'vertex', -- Vertex table
'id', -- Vertix id column
'"EDGE"', -- "EDGE" table
'src=src, dest=dest', -- "EDGE" args
'pagerank_ppr_grp_out', -- Output table of PageRank
NULL, -- Default damping factor (0.85)
NULL, -- Default max iters (100)
NULL, -- Default Threshold 
'user_id');

I will get result

madlib=# select * from pagerank_ppr_grp_out order by user_id, id; user_id | id | pagerank
---------+----+-------------------
1 | 0 | 0.05
1 | 0 | 0.05
1 | 1 | 0.614906399170753
1 | 2 | 0.614906399170753
2 | 0 | 0.075
2 | 1 | 0.13875
(6 rows)

where user_id=1, id=1, pagerank=0.05 appears twice.

We should correct it to only show distinct result.

 

Besides, for user_id=1, all pagerank scores should sum up to 1. The score for user_id=1, id=1 should be 0.475, and the score for user_id=1, id=2 should be 0.475. We should correct this calculation too.

 

Issue Links

• links to: GitHub Pull Request #294