>> postgres[5500]: [3-1] ERROR: duplicate key value violates unique
>> constraint "acm_topic_markers_marker_forum_id_idx"
>> postgres[5500]: [3-2] STATEMENT: DELETE FROM acm_topic_markers WHERE
>> marker_member_id = '16993' AND marker_forum_id = '383';
>> postgres[5500]: [3-3] INSERT INTO acm_topic_markers
>> (marker_member_id,marker_forum_id,...) VALUES(16993,383,...);
последовательность команд (которые приводят к ошибке) мы должны угадать?