From 2af0b9a57f8bc317d3b9e7bcee8671a656f9cfcd Mon Sep 17 00:00:00 2001 From: Javier Goizueta Date: Wed, 23 Dec 2015 12:42:40 +0100 Subject: [PATCH] Add function comments --- scripts-available/CDB_Overviews.sql | 43 ++++++++++++++++++++++++++++- 1 file changed, 42 insertions(+), 1 deletion(-) diff --git a/scripts-available/CDB_Overviews.sql b/scripts-available/CDB_Overviews.sql index 35baba5..541bf1d 100644 --- a/scripts-available/CDB_Overviews.sql +++ b/scripts-available/CDB_Overviews.sql @@ -106,6 +106,13 @@ AS $$ END $$ LANGUAGE PLPGSQL STABLE; +-- Experimental default strategy to assign a reference base Z level +-- to a cartodbfied table. The resulting Z level represents the +-- minimum scale level at which the table data can be rendered +-- without overcrowded results or loss of detail. +-- Parameters: +-- reloid: oid of the input table. It must be a cartodbfy'ed table. +-- Return value: Z level as an integer CREATE OR REPLACE FUNCTION _CDB_Dummy_Ref_Z_Strategy(reloid REGCLASS) RETURNS INTEGER AS $$ @@ -129,6 +136,14 @@ AS $$ END; $$ LANGUAGE PLPGSQL STABLE; +-- Overview table name for a given Z level and base dataset or overview table +-- Scope: private. +-- Parameters: +-- ref reference table (can be the base table of the dataset or an existing +-- overview) from which the overview is being generated. +-- ref_z Z level of the reference table +-- overview_z Z level of the overview to be named, must be smaller than ref_z +-- Return value: the name to be used for the overview CREATE OR REPLACE FUNCTION _CDB_Overview_Name(ref REGCLASS, ref_z INTEGER, overview_z INTEGER) RETURNS TEXT AS $$ @@ -148,6 +163,13 @@ AS $$ END $$ LANGUAGE PLPGSQL IMMUTABLE; +-- Experimental simplistic reduction method for point datasets to be used as a default. +-- Scope: private. +-- reloid original table (can be the base table of the dataset or an existing +-- overview) from which the overview is being generated. +-- ref_z Z level assigned to the original table +-- overview_z Z level of the overview to be generated, must be smaller than ref_z +-- Return value: Name of the generated overview table CREATE OR REPLACE FUNCTION _CDB_Dummy_Reduce_Strategy(reloid REGCLASS, ref_z INTEGER, overview_z INTEGER) RETURNS REGCLASS AS $$ @@ -157,7 +179,7 @@ AS $$ base_name TEXT; BEGIN overview_rel := _CDB_Overview_Name(reloid, ref_z, overview_z); - -- TODO: implement a proper reduction technique. + -- TODO: implement a proper sampling strategy; -- Here we're just inefficiently sampling the data to mantain -- the approximate visual density of the reference level. reduction := power(2, 2*(overview_z - ref_z)); @@ -263,6 +285,16 @@ BEGIN END $$ LANGUAGE PLPGSQL STABLE; +-- Experimental Overview reduction method for point datasets. +-- It clusters the points using a grid, then aggregates the point in each +-- cluster into a point at the centroid of the clustered records. +-- Scope: private. +-- Parameters: +-- reloid original table (can be the base table of the dataset or an existing +-- overview) from which the overview is being generated. +-- ref_z Z level assigned to the original table +-- overview_z Z level of the overview to be generated, must be smaller than ref_z +-- Return value: Name of the generated overview table CREATE OR REPLACE FUNCTION _CDB_GridCluster_Reduce_Strategy(reloid REGCLASS, ref_z INTEGER, overview_z INTEGER) RETURNS REGCLASS AS $$ @@ -321,6 +353,15 @@ AS $$ END; $$ LANGUAGE PLPGSQL; +-- Create overview tables for a dataset. +-- Scope: public +-- Parameters: +-- reloid: oid of the input table. It must be a cartodbfy'ed table with +-- vector features. +-- refscale_strategy: function that computes the reference Z of the dataset +-- reduce_strategy: function that generates overviews from a base table +-- or higher level overview +-- Return value: Array with the names of the generated overview tables CREATE OR REPLACE FUNCTION CDB_CreateOverviews( reloid REGCLASS, refscale_strategy regproc DEFAULT '_CDB_Dummy_Ref_Z_Strategy'::regproc,