> I have been reading all this technical talk about costs and such that
> I don't (_yet_) understand.
>
> Now I'm scared... what's the fastest way to do an equivalent of
> count(*) on a table to know how many items it has?
Make sure to analyze the database frequently and check pg_class for
reltup
The MPP test I ran was with the release version 2.0 of MPP which is based on
Postgres 8.0, the upcoming 2.1 release is based on 8.1, and 8.1 is far
faster at seq scan + agg. 12,937MB were counted in 4.5 seconds, or 2890MB/s
from I/O cache. That's 722MB/s per host, and 360MB/s per Postgres instanc
>
> It certainly makes quite a difference as I measure it:
>
> doing select(1) from a 181000 page table (completely uncached) on my
PIII:
>
> 8.0 : 32 s
> 8.1 : 25 s
>
> Note that the 'fastcount()' function takes 21 s in both cases - so all
> the improvement seems to be from the count overhead
Merlin Moncure wrote:
It certainly makes quite a difference as I measure it:
doing select(1) from a 181000 page table (completely uncached) on my
PIII:
8.0 : 32 s
8.1 : 25 s
Note that the 'fastcount()' function takes 21 s in both cases - so all
the improvement seems to be from the count ove
Mark,
On 11/28/05 1:45 PM, "Mark Kirkwood" <[EMAIL PROTECTED]> wrote:
>>> 8.0 : 32 s
>>> 8.1 : 25 s
A 22% reduction.
select count(1) on 12,900MB = 1617125 pages fully cached:
MPP based on 8.0 : 6.06s
MPP based on 8.1 : 4.45s
A 26% reduction.
I'll take it!
I am looking to back-port Tom's pre
Hi all,
I don't understand why this request take so long. Maybe I read the
analyse correctly but It seem that the first line(Nested Loop Left Join
...) take all the time. But I don't understand where the performance
problem is ??? All the time is passed in the first line ...
Thanks for
Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is it
possible to upgrade from Postgres 8.1 to Bizgres?
Thanks,
Brendan Duddridge | CTO | 403-277-5591 x24 | [EMAIL PROTECTED]
ClickSpace Interactive Inc.
Suit
David Gagnon wrote:
> " -> Index Scan using cr_pk on cr (cost=0.00..6.02 rows=1
> width=828) (actual time=0.073..0.077 rows=1 loops=13587)"
> "Index Cond: (((cr.crypnum)::text = 'M'::text) AND
> (cr.crnum = "outer".cscrnum))"
> "Filter: ((crda
Bricklen Anderson <[EMAIL PROTECTED]> writes:
> Your loops are what is causing the time spent.
> eg. "actual time=0.127..17.379 rows=1154 loops=8335)" ==
> 8335*(17.379-0.127)/1000=>143 secs (if my math is correct).
As for where the problem is, I think it's the horrid misestimate of the
number of
I restored my db but haven't run the analyse... That was the problem.
Thanks
/David
"Merge Left Join (cost=2273.54..2290.19 rows=228 width=816) (actual
time=2098.257..2444.472 rows=8335 loops=1)"
" Merge Cond: (("outer".rrnum)::text = "inner"."?column8?")"
" -> Merge Join (cost=2131.25..2
Hi David,
Thanks for your reply. So how is that different than something like
Slony2 or pgcluster with multi-master replication? Is it similar
technology? We're currently looking for a good clustering solution
that will work on our Apple Xserves and Xserve RAIDs.
Thanks,
Brendan Duddridge wrote:
Thanks for your reply. So how is that different than something like
Slony2 or pgcluster with multi-master replication? Is it similar
technology? We're currently looking for a good clustering solution
that will work on our Apple Xserves and Xserve RAIDs.
I think yo
On Mon, 28 Nov 2005, Brendan Duddridge wrote:
Hi David,
Thanks for your reply. So how is that different than something like Slony2 or
pgcluster with multi-master replication? Is it similar technology? We're
currently looking for a good clustering solution that will work on our Apple
Xserves
On Mon, 28 Nov 2005, Brendan Duddridge wrote:
Forgive my ignorance, but what is MPP? Is that part of Bizgres? Is it
possible to upgrade from Postgres 8.1 to Bizgres?
MPP is the Greenplum propriatary extention to postgres that spreads the
data over multiple machines, (raid, but with entire mac
I know in mysql, index will auto change after copying data
Of course, index will change after inserting a line in postgresql, but what
about copying data?
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