The proportion of mandatory and optional textual base table columns

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SELECT Count(*) FILTER (WHERE is_nullable='NO') AS number_of_mandatory_textual_columns,
Count(*) FILTER (WHERE is_nullable='YES') AS number_of_optional_textual_columns,
Count(*) AS  number_of_textual_columns
FROM information_schema.columns A INNER JOIN information_schema.schemata S ON A.table_schema=S.schema_name
WHERE A.data_type IN ('character varying','text','character') 
AND (A.table_schema = 'public'
OR S.schema_owner<>'postgres')
AND (table_schema, table_name) IN (SELECT table_schema, table_name
FROM information_schema.tables
WHERE table_type='BASE TABLE');