Github user orhankislal commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/112#discussion_r111033008
--- Diff: src/ports/postgres/modules/graph/pagerank.py_in ---
@@ -158,44 +313,198 @@ def pagerank(schema_madlib, vertex_table, vertex_id,
edge_table, edge_args,
# https://en.wikipedia.org/wiki/PageRank#Damping_factor
# The query below computes the PageRank of each node using the
above formula.
+ # A small explanatory note on ignore_group_clause:
+ # This is used only when grouping is set. This essentially will
have
+ # the condition that will help skip the PageRank computation on
groups
+ # that have converged.
plpy.execute("""
CREATE TABLE {message} AS
- SELECT {edge_temp_table}.{dest} AS {vertex_id},
-
SUM({v1}.pagerank/{out_cnts}.{out_cnts_cnt})*{damping_factor}+{random_prob} AS
pagerank
+ SELECT {grouping_cols_select} {edge_temp_table}.{dest} AS
{vertex_id},
+
SUM({v1}.pagerank/{out_cnts}.{out_cnts_cnt})*{damping_factor}+{random_jump_prob}
AS pagerank
FROM {edge_temp_table}
- INNER JOIN {cur} ON
{edge_temp_table}.{dest}={cur}.{vertex_id}
- INNER JOIN {out_cnts} ON
{out_cnts}.{vertex_id}={edge_temp_table}.{src}
- INNER JOIN {cur} AS {v1} ON
{v1}.{vertex_id}={edge_temp_table}.{src}
- GROUP BY {edge_temp_table}.{dest}
- """.format(**locals()))
+ INNER JOIN {cur} ON {cur_join_clause}
+ INNER JOIN {out_cnts} ON {out_cnts_join_clause}
+ INNER JOIN {cur} AS {v1} ON {v1_join_clause}
+ {vertices_per_group_inner_join}
+ {ignore_group_clause}
+ GROUP BY {grouping_cols_select} {edge_temp_table}.{dest}
+ """.format(grouping_cols_select=edge_grouping_cols_select+', '
--- End diff --
You might want to move these grouping_cols if checks out of the loop. You
can initialize them to empty strings (similar to lines 122 - 127) and overwrite
them when you have grouping (similar to lines 169 - 184). I am sure a C
compiler can take care of it automatically but I am not sure about python.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
