Github user njayaram2 commented on a diff in the pull request:
https://github.com/apache/incubator-madlib/pull/80#discussion_r92722081
--- Diff: src/ports/postgres/modules/knn/knn.sql_in ---
@@ -0,0 +1,126 @@
+/* -----------------------------------------------------------------------
*//**
+ *
+ * @file knn.sql_in
+ *
+ * @brief Set of functions for k-nearest neighbors.
+ *
+ *
+ *//*
----------------------------------------------------------------------- */
+
+m4_include(`SQLCommon.m4')
+
+DROP TYPE IF EXISTS MADLIB_SCHEMA.knn_result CASCADE;
+CREATE TYPE MADLIB_SCHEMA.knn_result AS (
+ prediction float
+);
+DROP TYPE IF EXISTS MADLIB_SCHEMA.test_table_spec CASCADE;
+CREATE TYPE MADLIB_SCHEMA.test_table_spec AS (
+ id integer,
+ vector DOUBLE PRECISION[]
+);
+
+CREATE OR REPLACE FUNCTION MADLIB_SCHEMA.__knn_validate_src(
+rel_source VARCHAR
+) RETURNS VOID AS $$
+ PythonFunction(knn, knn, knn_validate_src)
+$$ LANGUAGE plpythonu
+m4_ifdef(`__HAS_FUNCTION_PROPERTIES__', `READS SQL DATA', `');
+
+
+
+CREATE OR REPLACE FUNCTION MADLIB_SCHEMA.knn(
+ point_source VARCHAR,
+ point_column_name VARCHAR,
+ label_column_name VARCHAR,
+ test_source VARCHAR,
+ test_column_name VARCHAR,
+ id_column_name VARCHAR,
+ operation VARCHAR,
+ k INTEGER
+) RETURNS VARCHAR AS $$
+DECLARE
--- End diff --
We can also overload this function. At the moment it looks
like only `k` can be an optional parameter. So we should be
able to run knn with some default value of `k`, if not provided.
Showing help messages when we call `knn()` or `knn('help')`
are examples of overloading this function.
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