Columns with only one value

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ANALYZE;
SELECT ps.schemaname, ps.tablename, ps.attname, psat.n_live_tup AS num_rows
FROM pg_catalog.pg_stats AS ps INNER JOIN pg_catalog.pg_stat_all_tables AS psat
ON ps.schemaname=psat.schemaname AND ps.tablename=psat.relname
WHERE  ps.schemaname NOT IN (SELECT schema_name FROM INFORMATION_SCHEMA.schemata WHERE schema_name<>'public' AND schema_owner='postgres' AND schema_name IS NOT NULL) AND most_common_freqs = '{1}' AND psat.n_live_tup>1 
AND psat.last_analyze IS NOT NULL
ORDER BY psat.n_live_tup DESC, ps.schemaname, ps.tablename;