The following statements are executed within installing or starting the server the first time after updating to version 7.8.0:

CREATE TABLE guest (
id INT4 UNSIGNED NOT NULL,
mail_address VARCHAR(255) NOT NULL,
PRIMARY KEY (id),
INDEX (mail_address),
UNIQUE (id),
UNIQUE (mail_address)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

CREATE TABLE guest2context (
guest_id INT4 UNSIGNED NOT NULL,
cid INT4 UNSIGNED NOT NULL,
uid INT4 UNSIGNED NOT NULL,
PRIMARY KEY(, ,),
FOREIGN KEY() REFERENCES context (),
FOREIGN KEY() REFERENCES guest (uid=1000(service) gid=1000(service) Gruppen=1000(service)),
INDEX (guest_id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;