BEGIN
RETURN QUERY
EXECUTE
format(
'
SELECT
%1$I.*,
dist_query.distance AS appended_distance,
dist_query.centroid AS appended_centroid
FROM %1$I
INNER JOIN distance_search(%1$L, $1, $2, %2$L) AS dist_query
ON %1$I.%2$I=dist_query.%2$I;
',
pg_typeof(table_name),
id_column_name
)
USING search_area, buffer_size;
END;
CREATE FUNCTION [...]
RETURNS TABLE (primary_tbl anyelement, query_cols dist_query_type)
RETURN QUERY
EXECUTE
format($select_template$
SELECT %1$I, -- NO .*
ROW(dist_query.distance,dist_query,centroid)::dist_query_type,
FROM %1$I
JOIN distance_search(...) AS dist_query
ON (...)
[...]
Outputs two columns, one polymorphic match and one constant.
You can tack on additional columns instead using two composites but since you are forced to use a composite output column for "table1" for consistency I'd say you should use a composite output column for "table2" as well.
I couldn't figure out a way to get the output into columns.
function_tbl1 RETURNS TABLE (tbl anyelement) -- SELECT * FROM function_tbl1 explodes the single-column composite
function_tbl2 RETURNS TABLE (tbl anyelement, const text) -- SELECT * FROM function_tbl2 keeps the composite "unit-fied"
David J.
