Github user njayaram2 commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/141#discussion_r122319562
--- Diff: src/ports/postgres/modules/graph/bfs.py_in ---
@@ -0,0 +1,445 @@
+# coding=utf-8
+#
+# 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.
+
+# Breadth-First Search
+
+# Please refer to the bfs.sql_in file for the documentation
+
+"""
+@file bfs.py_in
+
+@namespace graph
+"""
+
+import plpy
+from graph_utils import *
+from utilities.control import MinWarning
+from utilities.utilities import _assert
+from utilities.utilities import extract_keyvalue_params
+from utilities.utilities import split_quoted_delimited_str
+from utilities.validate_args import table_exists
+from utilities.validate_args import columns_exist_in_table
+
+m4_changequote(`<!', `!>')
+
+def _validate_bfs(vertex_table, vertex_id, edge_table, edge_params,
+ source_vertex, out_table, max_distance, directed, grouping_cols_list,
**kwargs):
+
+ validate_graph_coding(vertex_table, vertex_id, edge_table, edge_params,
+ out_table,'BFS')
+
+ _assert((max_distance >= 0) and isinstance(max_distance,int),
+ """Graph BFS: Invalid max_distance type or value ({0}), must be
integer,
+ be greater than or equal to 0 and be less than max allowable
integer
+ (2147483647).""".
+ format(max_distance))
+
+ _assert(isinstance(directed,bool),
+ """Graph BFS: Invalid value for directed ({0}), must be
boolean.""".
+ format(directed))
+
+ _assert(isinstance(source_vertex,int),
+ """Graph BFS: Source vertex {source_vertex} has to be an
integer.""".
+ format(**locals()))
+ src_exists = plpy.execute("""
+ SELECT * FROM {vertex_table} WHERE {vertex_id}={source_vertex}
+ """.format(**locals()))
+ if src_exists.nrows() == 0:
+ plpy.error(
+ """Graph BFS: Source vertex {source_vertex} is not present in
the
+ vertex table {vertex_table}.""".
+ format(**locals()))
+
+ vt_error = plpy.execute(
+ """ SELECT {vertex_id}
+ FROM {vertex_table}
+ WHERE {vertex_id} IS NOT NULL
+ GROUP BY {vertex_id}
+ HAVING count(*) > 1 """.format(**locals()))
+ if vt_error.nrows() != 0:
+ plpy.error(
+ """Graph BFS: Source vertex table {vertex_table} contains
duplicate
+ vertex id's.""".
+ format(**locals()))
+
+ _assert(not table_exists(out_table+"_summary"),
+ "Graph BFS: Output summary table already exists!")
+
+ if grouping_cols_list is not None:
+ _assert(columns_exist_in_table(edge_table, grouping_cols_list),
+ """Graph BFS: Not all columns from {grouping_cols_list} are
present
+ in edge table ({edge_table}).""".
+ format(**locals()))
+
+ return None
+
+def _grp_from_table(tbl, grp_list):
+
+ """
+ Helper function for selecting grouping columns of a table
+ Args:
+ @param tbl Name of the table
+ @param grp_list The list of grouping columns
+ """
+ return ' , '.join([" {tbl}.{i} ".format(**locals())
+ for i in grp_list])
+
+def _grp_null_checks(grp_list):
+
+ """
+ Helper function for generating NULL checks for grouping columns
+ to be used within a WHERE clause
+ Args:
+ @param grp_list The list of grouping columns
+ """
+ return ' AND '.join([" {i} IS NOT NULL ".format(**locals())
+ for i in grp_list])
+
--- End diff --
Might be a good idea to move functions `_grp_null_checks ` and
`_grp_from_table ` to `utilities.validate_args.py_in`. If you do, I would
recommend changing the function names to capture the fact that these would
return some sql clauses.
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