cross database table references I try to create table GroupArticle in database CmsGroup, one column ArticleId references another table in another database? is this possible and correct syntax?

CmsArticle

CREATE DATABASE "CmsArticle"
WITH OWNER = db_admin
ENCODING = 'UTF8'
TABLESPACE = pg_default
LC_COLLATE = 'en_GB.UTF-8'
LC_CTYPE = 'en_GB.UTF-8'
CONNECTION LIMIT = -1;

CREATE TABLE IF NOT EXISTS "Article"(
"ArticleId" SERIAL NOT NULL,
"PublishDate" timestamp without time zone,
PRIMARY KEY ("ArticleId")
);


CmsGroup    

CREATE DATABASE "CmsGroup"
WITH OWNER = db_admin
ENCODING = 'UTF8'
TABLESPACE = pg_default
LC_COLLATE = 'en_GB.UTF-8'
LC_CTYPE = 'en_GB.UTF-8'
CONNECTION LIMIT = -1;

CREATE TABLE IF NOT EXISTS "Group"(
"GroupId" SERIAL NOT NULL,
"PublishDate" timestamp without time zone,
PRIMARY KEY ("GroupId")
);

CREATE TABLE IF NOT EXISTS "GroupArticle"(
"GroupArticleId" SERIAL NOT NULL,
"GroupId" integer NOT NULL,
"ArticleId" integer NOT NULL,
FOREIGN KEY ("GroupId") REFERENCES "Group" ("GroupId") ON DELETE CASCADE ON UPDATE CASCADE,
FOREIGN KEY ("ArticleId") REFERENCES "CmsArticle.Article" ("ArticleId") ON DELETE CASCADE ON UPDATE CASCADE,
PRIMARY KEY ("GroupArticleId")
);
NO. You cannot create foreign key references on a different database. 

Create the tables on the same database, if there is no specific reason to have them in separate databases.