adding _OBS_GetRelatedColumn function

src/pg/sql/40_observatory_utility.sql

@@ -151,3 +151,25 @@ BEGIN
 
 END;
 $$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION cdb_observatory._GetRelatedColumn(columns_ids text[], reltype text )
+RETURNS TEXT[]
+AS $$
+DECLARE
+  result TEXT[];
+BEGIN
+  EXECUTE '
+    With ids as (
+      select row_number() over() as no, id from (select unnest($1) as id) t
+    )
+    select array_agg(target_id order by no)
+    FROM  ids
+    LEFT JOIN observatory.obs_column_to_column
+    on  source_id  = id
+    where reltype = $2 or reltype is null
+  '
+  INTO result
+  using columns_ids, reltype;
+  return result;
+END;
+$$ LANGUAGE plpgsql;

src/pg/test/expected/40_observatory_utility_test.out

@@ -29,7 +29,7 @@ SELECT
     CDB_LatLng(40.7128,-74.0059),
     '"us.census.tiger".census_tract'
   );
-                _obs_geomtable                
+                _obs_geomtable
 ----------------------------------------------
  obs_a92e1111ad3177676471d66bb8036e6d057f271b
 (1 row)
@@ -41,9 +41,9 @@ SELECT
     CDB_LatLng(40.7128,-74.0059),
     '"us.census.tiger".nonexistant_id' -- not in catalog
   );
- _obs_geomtable 
+ _obs_geomtable
 ----------------
- 
+
 (1 row)
 
 -- future test: give back nulls when geometry doesn't intersect
@@ -65,11 +65,11 @@ SELECT
     '2009 - 2013'
   ))).*
 ORDER BY colname, tablename ASC;
-  colname  |                  tablename                   | aggregate 
+  colname  |                  tablename                   | aggregate
 -----------+----------------------------------------------+-----------
- geoid     | obs_11ee8b82c877c073438bc935a91d3dfccef875d1 | 
- geoid     | obs_ab038198aaab3f3cb055758638ee4de28ad70146 | 
- geoid     | obs_d34555209878e8c4b37cf0b2b3d072ff129ec470 | 
+ geoid     | obs_11ee8b82c877c073438bc935a91d3dfccef875d1 |
+ geoid     | obs_ab038198aaab3f3cb055758638ee4de28ad70146 |
+ geoid     | obs_d34555209878e8c4b37cf0b2b3d072ff129ec470 |
  total_pop | obs_ab038198aaab3f3cb055758638ee4de28ad70146 | sum
 (4 rows)
 
@@ -81,7 +81,7 @@ SELECT
     '2009 - 2013'
   ))).*
 ORDER BY 1 ASC;
- colname | tablename | aggregate 
+ colname | tablename | aggregate
 ---------+-----------+-----------
 (0 rows)
 
@@ -91,7 +91,7 @@ SELECT
   cdb_observatory._OBS_LookupCensusHuman(
     Array['gini_index']
   );
-     _obs_lookupcensushuman      
+     _obs_lookupcensushuman
 ---------------------------------
  {"\"us.census.acs\".B19083001"}
 (1 row)
@@ -101,9 +101,9 @@ SELECT
   cdb_observatory._OBS_LookupCensusHuman(
     Array['cookies']
   );
- _obs_lookupcensushuman 
+ _obs_lookupcensushuman
 ------------------------
- 
+
 (1 row)
 
 -- OBS_BuildSnapshotQuery
@@ -112,7 +112,7 @@ SELECT
   cdb_observatory._OBS_BuildSnapshotQuery(
     Array['total_pop','male_pop','female_pop','median_age']
   );
-                                     _obs_buildsnapshotquery                                     
+                                     _obs_buildsnapshotquery
 -------------------------------------------------------------------------------------------------
  SELECT  vals[1] As total_pop, vals[2] As male_pop, vals[3] As female_pop, vals[4] As median_age
 (1 row)
@@ -122,11 +122,26 @@ SELECT
   cdb_observatory._OBS_BuildSnapshotQuery(
     Array['mandarin_orange']
   );
-      _obs_buildsnapshotquery       
+      _obs_buildsnapshotquery
 ------------------------------------
  SELECT  vals[1] As mandarin_orange
 (1 row)
 
+-- should give back "\"es.ine\".total_pop",NULL,"\"us.census.acs\".B01001001"}
+SELECT
+  select * from  cdb_observatory._GetRelatedColumn(
+    Array[
+    '"es.ine".pop_0_4',
+     '"us.census.acs".B01001001',
+    '"us.census.acs".B01001002'
+    ],
+     'denominator'
+ );
+                     _getrelatedcolumn
+-------------------------------------------------------------
+{"\"es.ine\".total_pop",NULL,"\"us.census.acs\".B01001001"}
+(1 row)
+
 \i test/sql/drop_fixtures.sql
 SET client_min_messages TO NOTICE;
 \set ECHO none

src/pg/test/sql/40_observatory_utility_test.sql

@@ -75,4 +75,14 @@ SELECT
     Array['mandarin_orange']
   );
 
+SELECT
+  select * from  cdb_observatory._GetRelatedColumn(
+    Array[
+    '"es.ine".pop_0_4',
+     '"us.census.acs".B01001001',
+    '"us.census.acs".B01001002'
+    ],
+     'denominator'
+ );
+
 \i test/sql/drop_fixtures.sql