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From orhankislal <>
Subject [GitHub] incubator-madlib pull request #112: Feautre: Add grouping support for PageRa...
Date Wed, 12 Apr 2017 00:06:47 GMT
Github user orhankislal commented on a diff in the pull request:
    --- Diff: src/ports/postgres/modules/graph/pagerank.py_in ---
    @@ -158,44 +313,198 @@ def pagerank(schema_madlib, vertex_table, vertex_id, edge_table,
             # 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.
                     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. 

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