PGSQL查询慢索引

SELECT
    n.nspname AS schemaname,
    c.relname AS tablename,
    i.relname AS indexname,
    t.spcname AS tablespace,
    pg_get_indexdef(i.oid) AS indexdef
FROM pg_index x
    JOIN pg_class c ON c.oid = x.indrelid
    JOIN pg_class i ON i.oid = x.indexrelid
    LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
    LEFT JOIN pg_tablespace t ON t.oid = i.reltablespace
WHERE (c.relkind = ANY (ARRAY['r'::"char", 'm'::"char"])) AND i.relkind = 'i'::"char"
and n.nspname='';