在亚马逊 ec2 RDS Postgresql：

=> SHOW rds.extensions;

rds.extensions                                                                                                                                 
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 btree_gin,btree_gist,chkpass,citext,cube,dblink,dict_int,dict_xsyn,earthdistance,fuzzystrmatch,hstore,intagg,intarray,isn,ltree,pgcrypto,pgrowlocks,pg_trgm,plperl,plpgsql,pltcl,postgis,postgis_tiger_geocoder,postgis_topology,sslinfo,tablefunc,tsearch2,unaccent,uuid-ossp
(1 row)

如您所见，uuid-ossp扩展确实存在。但是，当我为 generation 调用函数时uuid_v4，它失败了：

CREATE TABLE my_table (
    id uuid DEFAULT uuid_generate_v4() NOT NULL,
    name character varying(32) NOT NULL,

);

这有什么问题？