CREATE OR REPLACE FUNCTION _final_median(NUMERIC[])
   RETURNS NUMERIC AS
$$
   SELECT AVG(val)
   FROM (
     SELECT val
     FROM unnest($1) val
     ORDER BY 1
     LIMIT  2 - MOD(array_upper($1, 1), 2)
     OFFSET CEIL(array_upper($1, 1) / 2.0) - 1
   ) sub;
$$
LANGUAGE 'sql' IMMUTABLE;
CREATE OR REPLACE AGGREGATE median(NUMERIC) (
  SFUNC=array_append,
  STYPE=NUMERIC[],
  FINALFUNC=_final_median,
  INITCOND='{}'
);

WITH number_of_columns AS (SELECT table_schema, table_name, table_type, Count(*) AS number_of_columns
FROM information_schema.columns AS c INNER JOIN INFORMATION_SCHEMA.tables AS t USING  (table_schema, table_name) 
WHERE c.table_schema NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL) 
GROUP BY table_schema, table_name, table_type
UNION SELECT nspname, relname, 'MATERIALIZED VIEW' AS table_type, Count(*) AS number_of_columns
FROM pg_class INNER JOIN pg_namespace ON pg_class.relnamespace=pg_namespace.oid
INNER JOIN pg_attribute ON pg_class.oid=pg_attribute.attrelid
WHERE relkind = 'm' AND attnum>=1 AND 
nspname NOT IN (SELECT schema_name
FROM INFORMATION_SCHEMA.schemata
WHERE schema_name<>'public' AND
schema_owner='postgres' AND schema_name IS NOT NULL)
GROUP BY nspname, relname)
SELECT table_type, table_schema,
Sum(number_of_columns) total_nr_of_cols,
Round(Median(number_of_columns),1) AS median_nr_of_cols,
Round(Avg(number_of_columns),1) AS average_nr_of_cols,
Max(number_of_columns) AS the_biggest_nr_of_cols,
Min(number_of_columns) AS the_smallest_nr_of_cols
FROM number_of_columns
GROUP BY CUBE (table_type, table_schema);

DROP FUNCTION IF EXISTS _final_median(NUMERIC[]) CASCADE; 
DROP AGGREGATE IF EXISTS median(numeric);