We're testing running Keycloak against a MySQL cluster, and we ran into this issue. It seems that MySQL cluster requires all tables to have a primary key constraint. Our DBA queried which ones are not compliant into the Keycloak schema and the result is the following:

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We guessed the following constraints:

alter table ADMIN_EVENT_ENTITY add primary key (ID);

alter table CLIENT_DEFAULT_ROLES add primary key (CLIENT_ID,ROLE_ID);

alter table CLIENT_IDENTITY_PROV_MAPPING add primary key (CLIENT_ID,IDENTITY_PROVIDER_ID);

alter table COMPOSITE_ROLE add primary key (COMPOSITE,CHILD_ROLE);

alter table CREDENTIAL_ATTRIBUTE add primary key (ID);

alter table DATABASECHANGELOG add primary key (ID,ORDEREXECUTED);

alter table FED_CREDENTIAL_ATTRIBUTE add primary key (ID);

alter table REALM_DEFAULT_GROUPS add primary key (REALM_ID,GROUP_ID);

alter table REALM_DEFAULT_ROLES add primary key (REALM_ID,ROLE_ID);

alter table REALM_ENABLED_EVENT_TYPES add primary key (REALM_ID,`VALUE`);

alter table REALM_EVENTS_LISTENERS add primary key (REALM_ID,`VALUE`);

alter table REALM_SUPPORTED_LOCALES add primary key (REALM_ID,`VALUE`);
alter table REDIRECT_URIS add primary key (CLIENT_ID,`VALUE`);

alter table WEB_ORIGINS add primary key (CLIENT_ID,`VALUE`);

But we would rather have an upstream solution.