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* Odd error message (" hash indexes do not support whole-index scans")
@ 2005-04-20 15:23 Marinos Yannikos <mjy@geizhals.at>
2005-04-20 16:02 ` Re: Odd error message (" hash indexes do not support whole-index scans") Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 3+ messages in thread
From: Marinos Yannikos @ 2005-04-20 15:23 UTC (permalink / raw)
To: pgsql-sql
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
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Odd error message (" hash indexes do not support whole-index scans")
2005-04-20 15:23 Odd error message (" hash indexes do not support whole-index scans") Marinos Yannikos <mjy@geizhals.at>
@ 2005-04-20 16:02 ` Tom Lane <tgl@sss.pgh.pa.us>
2005-04-22 02:08 ` Re: Odd error message (" hash indexes do not support whole-index Marinos Yannikos <mjy@geizhals.at>
0 siblings, 1 reply; 3+ messages in thread
From: Tom Lane @ 2005-04-20 16:02 UTC (permalink / raw)
To: Marinos Yannikos <mjy@geizhals.at>; +Cc: pgsql-sql
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
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Odd error message (" hash indexes do not support whole-index
2005-04-20 15:23 Odd error message (" hash indexes do not support whole-index scans") Marinos Yannikos <mjy@geizhals.at>
2005-04-20 16:02 ` Re: Odd error message (" hash indexes do not support whole-index scans") Tom Lane <tgl@sss.pgh.pa.us>
@ 2005-04-22 02:08 ` Marinos Yannikos <mjy@geizhals.at>
0 siblings, 0 replies; 3+ messages in thread
From: Marinos Yannikos @ 2005-04-22 02:08 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: pgsql-sql
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
^ permalink raw reply [nested|flat] 3+ messages in thread
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2005-04-20 15:23 Odd error message (" hash indexes do not support whole-index scans") Marinos Yannikos <mjy@geizhals.at>
2005-04-20 16:02 ` Tom Lane <tgl@sss.pgh.pa.us>
2005-04-22 02:08 ` Re: Odd error message (" hash indexes do not support whole-index Marinos Yannikos <mjy@geizhals.at>
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