Github user njayaram2 commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/144#discussion_r124682389
--- Diff: src/ports/postgres/modules/graph/wcc.sql_in ---
@@ -0,0 +1,261 @@
+/* -----------------------------------------------------------------------
*//**
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ *
+ *
+ * @file graph.sql_in
+ *
+ * @brief SQL functions for graph analytics
+ * @date June 2017
+ *
+ * @sa Provides various graph algorithms.
+ *
+ *//*
----------------------------------------------------------------------- */
+m4_include(`SQLCommon.m4')
+
+
+/**
+@addtogroup grp_wcc
+
+<div class="toc"><b>Contents</b>
+<ul>
+<li><a href="#wcc">Weakly Connected Components</a></li>
+<li><a href="#notes">Notes</a></li>
+<li><a href="#examples">Examples</a></li>
+<li><a href="#literature">Literature</a></li>
+</ul>
+</div>
+
+@brief Find all weakly connected components of a graph.
+
+Given a directed graph, a weakly connected component is a subgraph of the
original
+graph where all vertices are connected to each other by some path,
ignoring the
+direction of edges. In case of an undirected graph, a weakly connected
component is
+also a strongly connected component.
+
+@anchor wcc
+@par Weakly Connected Components
+<pre class="syntax">
+weakly_connected_components( vertex_table,
+ vertex_id,
+ edge_table,
+ edge_args,
+ out_table,
+ grouping_cols
+ )
+</pre>
+
+\b Arguments
+<dl class="arglist">
+<dt>vertex_table</dt>
+<dd>TEXT. Name of the table containing the vertex data for the graph. Must
contain the
+column specified in the 'vertex_id' parameter below.</dd>
+
+<dt>vertex_id</dt>
+<dd>TEXT, default = 'id'. Name of the column in 'vertex_table' containing
+vertex ids. The vertex ids are of type INTEGER with no duplicates.
+They do not need to be contiguous.</dd>
+
+<dt>edge_table</dt>
+<dd>TEXT. Name of the table containing the edge data. The edge table must
+contain columns for source vertex and destination vertex.</dd>
+
+<dt>edge_args</dt>
+<dd>TEXT. A comma-delimited string containing multiple named arguments of
+the form "name=value". The following parameters are supported for
+this string argument:
+ - src (INTEGER): Name of the column containing the source vertex ids in
the edge table.
+ Default column name is 'src'.
+ - dest (INTEGER): Name of the column containing the destination vertex
ids in the edge table.
+ Default column name is 'dest'.</dd>
+
+<dt>out_table</dt>
+<dd>TEXT. Name of the table to store the component ID associated with each
vertex.
+It will contain a row for every vertex from 'vertex_table' with
+the following columns:
+ - vertex_id : The id of a vertex. Will use the input parameter
'vertex_id' for column naming.
+ - component_id : The vertex's component.
+ - grouping_cols : Grouping column (if any) values associated with the
vertex_id.</dd>
+
+<dt>grouping_cols (optional)</dt>
--- End diff --
Will do.
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