Exclude certain columns from sync if instructed to do so

For the Geocoding (and in general for LDS use cases) it may come in
handy to exclude geometry columns from the list of stuff to
syncrhonize. Otherwise they may be lost, overwritten with NULL values.

scripts-available/CDB_SyncTable.sql

@@ -80,7 +80,7 @@ $$ LANGUAGE sql VOLATILE PARALLEL UNSAFE;
      SELECT CDB_SyncTable('radar_stations', 'public', 'syncdest');
 
 */
-CREATE OR REPLACE FUNCTION CDB_SyncTable(src_table REGCLASS, dst_schema REGNAMESPACE, dst_table NAME)
+CREATE OR REPLACE FUNCTION CDB_SyncTable(src_table REGCLASS, dst_schema REGNAMESPACE, dst_table NAME, skip_cols NAME[] = '{}')
 RETURNS void
 AS $$
 DECLARE
@@ -106,8 +106,10 @@ BEGIN
     RETURN;
   END IF;
 
-  -- Get the list of columns from the source table, excluding cartodb_id
+  skip_cols := skip_cols || '{cartodb_id}';
-  SELECT ARRAY(SELECT quote_ident(c) FROM _CDB_GetColumns(src_table) as c WHERE c <> 'cartodb_id') INTO colnames;
+
+  -- Get the list of columns from the source table, excluding skip_cols
+  SELECT ARRAY(SELECT quote_ident(c) FROM _CDB_GetColumns(src_table) as c EXCEPT SELECT unnest(skip_cols)) INTO colnames;
   quoted_colnames := array_to_string(colnames, ',');
 
   src_hash_table_name := __CDB_GenerateUniqueName('src_sync');

test/CDB_SyncTableTest.sql

@@ -40,5 +40,19 @@ SELECT * FROM test_sync_source ORDER BY cartodb_id;
 SELECT * FROM test_sync_dest ORDER BY cartodb_id;
 
 
+\echo 'It shall exclude geom columns if instructed to do so'
+\set QUIET on
+SET client_min_messages TO error;
+SELECT cartodb.CDB_SetUserQuotaInBytes(0); -- Set user quota to infinite
+SELECT cartodb.CDB_CartodbfyTable('test_sync_source');
+SELECT cartodb.CDB_CartodbfyTable('test_sync_dest');
+UPDATE test_sync_dest SET the_geom = cartodb.CDB_LatLng(lat, lon); -- A "gecoding"
+\set QUIET off
+SET client_min_messages TO notice;
+SELECT cartodb.CDB_SyncTable('test_sync_source', 'public', 'test_sync_dest', '{the_geom, the_geom_webmercator}');
+SELECT * FROM test_sync_source;
+SELECT * FROM test_sync_dest;
+
+
 -- Cleanup
 ROLLBACK;

test/CDB_SyncTableTest_expect

@@ -37,4 +37,25 @@ Sanity check: the end result is the same source table
 2|2|2|bar
 4|4|4|cantaloupe
 5|5|5|sandia
+It shall exclude geom columns if instructed to do so
+0
+test_sync_source
+test_sync_dest
+SET
+NOTICE:  relation "test_sync_dest" already exists, skipping
+NOTICE:  cdb_invalidate_varnish(public.test_sync_dest) called
+NOTICE:  DELETED 0 row(s)
+NOTICE:  cdb_invalidate_varnish(public.test_sync_dest) called
+NOTICE:  INSERTED 0 row(s)
+NOTICE:  cdb_invalidate_varnish(public.test_sync_dest) called
+NOTICE:  MODIFIED 0 row(s)
+
+1|||1|1|foo
+2|||2|2|bar
+5|||5|5|sandia
+4|||4|4|cantaloupe
+1|0101000020E6100000000000000000F03F000000000000F03F|0101000020110F0000DB0B4ADA772DFB402B432E49D22DFB40|1|1|foo
+2|0101000020E610000000000000000000400000000000000040|0101000020110F00003C0C4ADA772D0B4177F404ABE12E0B41|2|2|bar
+5|0101000020E610000000000000000014400000000000001440|0101000020110F000099476EE86AFC20413E7EB983F2012141|5|5|sandia
+4|0101000020E610000000000000000010400000000000001040|0101000020110F00003C0C4ADA772D1B4160AB497020331B41|4|4|cantaloupe
 ROLLBACK