Github user iyerr3 commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/105#discussion_r103325238
--- Diff: doc/design/modules/graph.tex ---
@@ -33,9 +34,53 @@
This module implements various graph algorithms that are used in a number
of applications such as social networks, telecommunications and road networks.
-% \section{Graph Representation} \label{sec:graph:rep}
+\section{Graph Framework} \label{sec:graph:fw}
+
+MADlib graph representation depends on two structures, a \emph{vertex}
table and an \emph{edge} table. The vertex table has to have a column of vertex
ids. The edge table has to have 2 columns: source vertex id, destination vertex
id. For most algorithms an edge weight column is required as well. The
representation assumes a directed graph, an edge from $x$ to $y$ does
\emph{not} guarantee the existence of an edge from $y$ to $x$. Both of the
tables may have additional columns as required. Multi-edges (multiple edges
from a vertex to the same destination) and loops (edge from a vertex to itself)
are allowed. For ideal performance, vertex and edge tables should be
distributed on vertex id and source id respectively. This representation does
not impose any ordering of vertices or edges. An example graph is given in
Figure~\ref{sssp:example} and its representative tables are given in
Table~\ref{sssp:rep}.
--- End diff --
Using an example considerably helps in understanding the algorithms.
1. Please reformat to width of 80 characters.
2. The note about performance is alogrithm-specific and would not
necessarily generalize for all graphs. I suggest not talking about it here.
Maybe make it a note within each algorithm description.
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