Обсуждение: Odd error message (" hash indexes do not support whole-index scans")
Shouldn't PostgreSQL behave in a different way in this case? (e.g. just not use the index): Table "public.forum_messages" message_id | integer | not null default nextval('forum_messages_message_id_seq'::text) parent_userid | integer | supersededby | integer | default 0 "forum_messages_pkey" primary key, btree (message_id) "idx_supersede" hash (supersededby) WHERE (supersededby > 0) # select m1.message_id,m2.message_id,m1.parent_userid,m2.parent_userid from forum_messages m1, forum_messages m2 where m2.supersededby=m1.message_id and m2.supersededby>0; ERROR: hash indexes do not support whole-index scans Regards, Marinos
Marinos Yannikos <mjy@geizhals.at> writes: > Shouldn't PostgreSQL behave in a different way in this case? (e.g. just > not use the index): Good catch. But why are you using a hash index for this? regards, tom lane
Tom Lane wrote: > Good catch. But why are you using a hash index for this? Just experimenting - I was trying to determine whether a hash index would give better performance - the values are always unique except when they're 0 and < > relations are never needed. That particular query would have been needed only once for maintainance work. Regards, Marinos