From: Paul Ramsey <pramsey@cleverelephant.ca>
Date: Thu, 6 Dec 2012 17:56:37 +0000 (+0000)
Subject: #2101, add some doco in the .sql.in.c file on the _postgis_* stats info functions.
X-Git-Tag: 2.1.0beta2~320
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9d107d92e01bf834bca481fc88211eb53ef9d220;p=postgis

#2101, add some doco in the .sql.in.c file on the _postgis_* stats info functions.


git-svn-id: http://svn.osgeo.org/postgis/trunk@10806 b70326c6-7e19-0410-871a-916f4a2858ee
---

diff --git a/postgis/postgis.sql.in.c b/postgis/postgis.sql.in.c
index 86ac21934..5b7beb4ac 100644
--- a/postgis/postgis.sql.in.c
+++ b/postgis/postgis.sql.in.c
@@ -432,18 +432,28 @@ CREATE OR REPLACE FUNCTION geometry_gist_joinsel_2d(internal, oid, internal, sma
 -----------------------------------------------------------------------------
 
 -- Availability: 2.1.0
+-- Given a table, column and query geometry, returns the estimate of what proportion
+-- of the table would be returned by a query using the &&/&&& operators. The mode
+-- changes whether the estimate is in x/y only or in all available dimensions.
 CREATE OR REPLACE FUNCTION _postgis_selectivity(tbl regclass, att_name text, geom geometry, mode text default '2')
 	RETURNS float8
 	AS 'MODULE_PATHNAME', '_postgis_gserialized_sel'
 	LANGUAGE 'c' STRICT;
 
 -- Availability: 2.1.0
+-- Given a two tables and columns, returns estimate of the proportion of rows
+-- a &&/&&& join will return relative to the number of rows an unconstrained
+-- table join would return. Mode flips result between evaluation in x/y only
+-- and evaluation in all available dimensions.
 CREATE OR REPLACE FUNCTION _postgis_join_selectivity(regclass, text, regclass, text, text default '2')
 	RETURNS float8
 	AS 'MODULE_PATHNAME', '_postgis_gserialized_joinsel'
 	LANGUAGE 'c' STRICT;
 
 -- Availability: 2.1.0
+-- Given a table and a column, returns the statistics information stored by 
+-- PostgreSQL, in a JSON text form. Mode determines whether the 2D statistics
+-- or the ND statistics are returned.
 CREATE OR REPLACE FUNCTION _postgis_stats(tbl regclass, att_name text, text default '2')
 	RETURNS text
 	AS 'MODULE_PATHNAME', '_postgis_gserialized_stats'