Problem

The external task table has a foreign key to the byte array table.

alter table ACT_RU_EXT_TASK
    add constraint ACT_FK_EXT_TASK_ERROR_DETAILS
    foreign key (ERROR_DETAILS_ID_)
    references ACT_GE_BYTEARRAY (ID_);

But there is no index on the ERROR_DETAILS_ID_ column. In the case a byte array is deleted some databases may lock the whole external task table, which can lead to a deadlock.

AT:

• create index on ERROR_DETAILS_ID_ in external task table