Re: [PERFORM] avoiding seqscan?

[Palle Girgensohn]

Will that make a difference? From what I've seen, it does not make much 
difference, but I have seen queries speed up when rewritten explicit joins. 
I guess it depends on other things, but is it really so that the explicit 
joins are bad somehow? Do you have any pointers to documentation about it, 
if so?

Thanks,
Palle
--On måndag, september 29, 2003 00.54.43 +0200 Gaetano Mendola 
<[EMAIL PROTECTED]> wrote:

Palle Girgensohn wrote:
uu=# explain analyze
uu-#  select lower(substr(p.last_name,1,1)) as letter, count(*)
uu-#  FROM course c join group_data gd on (c.active_group_id =
gd.this_group_id)
uu-#       join person p on (gd.item_text = p.userid)
uu-#       join dyn_field_person dfp on (dfp.extern_item_id = 10 and
dfp.giver=c.giver)
uu-#       join dyn_field_content_person dfcp on (dfp.id =
dfcp.dyn_field_id and dfcp.userid=p.userid)
uu-#       left outer join participant pt on (pt.userid = p.userid and
pt.course_id = 707)
uu-#  WHERE c.id = 707
uu-#  group by 1
uu-# ;
Why are you using this form of join ? When and if is not necessary use
the implicit form.
Regards
Gaetano Mendola






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