select table_owner,table_name, COALESCE(distribution_keys,'DISTRIBUTED RANDOMLY') distribution_keys

(

SELECT pgn.nspname as table_owner,
pgc.relname as table_name,
pga.attname as distribution_keys
FROM (SELECT gdp.localoid,
CASE
WHEN ( Array_upper(gdp.attrnums, 1) > 0 ) THEN
Unnest(gdp.attrnums)
ELSE NULL
END AS attnum
FROM gp_distribution_policy gdp
ORDER BY gdp.localoid) AS distrokey
INNER JOIN pg_class AS pgc
ON distrokey.localoid = pgc.oid
INNER JOIN pg_namespace pgn
ON pgc.relnamespace = pgn.oid
LEFT OUTER JOIN pg_attribute pga
ON distrokey.attnum = pga.attnum
AND distrokey.localoid = pga.attrelid
ORDER BY pgn.nspname,
pgc.relname) as a

where upper(a.table_owner)='PUBLIC' and lower(a.table_name)='abc';