I don't know if this is true in this case, but transaction level can be
different, in mssql it is normally something like
TRANSACTION_READ_UNCOMMITTED
in postgres
TRANSACTION_READ_COMMITTED
and that makes huge difference in performance.
other thing can be the queries in procedures, if you use sa
Hi,
how about:
select sf.library_id, fio.clip_type , count(sf.sequence_id)
fromsequence_fragment sf, fragment_external_info fio
,(SELECT distinct sequence_id from sequence_alignment) sa
where sf.seq_frag_id = fio.sequence_frag_id
and sf.sequence_id = sa.sequence_id
group by s
On Tue, 8 May 2007, Pomarede Nicolas wrote:
> As you can see, with hundreds of thousands events a day, this table will need
> being vaccumed regularly to avoid taking too much space (data and index).
>
> Note that processing rows is quite fast in fact, so at any time a count(*) on
> this table
I don't know about postgres, but in oracle it could be better to write:
SELECT COUNT(distinct c.id)
FROM t_oa_2_00_card c,l_pvcp l
WHERE l.value ilike '%pi%' and c.pvcp=l.id;
or
SELECT COUNT(c.id)
FROM t_oa_2_00_card c,
(select distinct id from l_pvcp where value ilike '%pi%') l
WHERE c.pvcp=l
approximated count?
why? who would need it? where you can use it?
calculating costs and desiding how to execute query needs
approximated count, but it's totally worthless information for any user
IMO.
Ismo
On Thu, 22 Mar 2007, Albert Cervera Areny wrote:
> As you can see, PostgreSQL nee
explain is just "quessing" how many rows are in table. sometimes quess is
right, sometimes just an estimate.
sailabdb=# explain SELECT count(*) from sl_tuote;
QUERY PLAN
--
Are you sure that:
SELECT count(distinct s.id) AS count_all
FROM symptoms s ,symptom_reports sr,users u
WHERE s.id=sr.symptom_id and sr.user_id=u.id and u.disease_id=1;
is as slow as
SELECT count(*) AS count_all
FROM symptoms
WHERE (1=1 and symptoms.id in (
select symptom_id from symptom_re
how about saying:
lock table versions_9d in EXCLUSIVE mode;
UPDATE versions_9d SET flag=2;
commit;
Ismo
On Thu, 22 Feb 2007, Gabriel Biberian wrote:
> Hello,
>
> I experience significant performance issues with postgresql and updates.
> I have a table which contains ~1M rows.
> Layout:
> TOTO
try:
select studentid,max(score) from studentprofile group by studentid;
or if you want only those which exists in students
select s.studentid,max(p.score)
from studentprofile p,students s
where s.studentid=p.studentid
group by s.studentid;
if it takes longer than 1-2 seconds something is seri
Hi,
I have used postgresql some years now, but only small databases and only
one database per instance and one user per database.
Now we have a server reserved only for postgresql, and I'm wondering if it
is better to set up:
- only one instance and many databases or
- many instances and only o
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