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* Hot Issue
@ 2008-07-02 12:31 Gauri Kanekar <meetgaurikanekar@gmail.com>
0 siblings, 2 replies; 12+ messages in thread
From: Gauri Kanekar @ 2008-07-02 12:31 UTC (permalink / raw)
To: pgsql-performance
Hi all,
We have upgraded our database server to postgres 8.3.1 on 28th June.
Checked out the performance of Hot on 30th June :
relname n_tup_ins n_tup_upd n_tup_del n_tup_hot_upd
n_live_tup n_dead_tup *table1* *15509156* *2884653* *0* *2442823* *
15509158* *68046* table2 434585 718472 0 642336 434703 16723 table3 105546
252143 0 233078 105402 4922 table4 7303628 96098 176790 23445 7126838 3443
table5 11117045 22245 0 16910 11117045 440
Checked the performance of Hot on 2nd July :
relname n_tup_ins n_tup_upd n_tup_del n_tup_hot_upd
n_live_tup n_dead_tup *table1**15577724* *6237242* *0* *2924948* *
18460676* *131103* table2 435558 1579613 0 763397 1171497 42476 table3
105814 540997 0 273443 355287 14184 table4 7614752 219329 513268 41053
7424721 62 table5 11184309 47665 0 21198 11206296 745
Performance of Hot was much better on 30June as compared to 2nd July.
Can anybody , help out over here.
~ Gauri
relname
n_tup_ins
n_tup_upd
n_tup_del
n_tup_hot_upd
n_live_tup
n_dead_tup
--
Regards
Gauri
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 12:40 Jonah H. Harris <jonah.harris@gmail.com>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
1 sibling, 1 reply; 12+ messages in thread
From: Jonah H. Harris @ 2008-07-02 12:40 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: pgsql-performance
On Wed, Jul 2, 2008 at 8:31 AM, Gauri Kanekar
<meetgaurikanekar@gmail.com> wrote:
> Performance of Hot was much better on 30June as compared to 2nd July.
Did you happen to VACUUM FULL or CLUSTER anything?
--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation | fax: 732.331.1301
499 Thornall Street, 2nd Floor | jonah.harris@enterprisedb.com
Edison, NJ 08837 | http://www.enterprisedb.com/
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 12:41 Gauri Kanekar <meetgaurikanekar@gmail.com>
parent: Jonah H. Harris <jonah.harris@gmail.com>
0 siblings, 0 replies; 12+ messages in thread
From: Gauri Kanekar @ 2008-07-02 12:41 UTC (permalink / raw)
To: Jonah H. Harris <jonah.harris@gmail.com>; +Cc: pgsql-performance
No, Vacuum Full was not done, but auto_vacuum did click onto table1.
No cluster.
On Wed, Jul 2, 2008 at 6:10 PM, Jonah H. Harris <jonah.harris@gmail.com>
wrote:
> On Wed, Jul 2, 2008 at 8:31 AM, Gauri Kanekar
> <meetgaurikanekar@gmail.com> wrote:
> > Performance of Hot was much better on 30June as compared to 2nd July.
>
> Did you happen to VACUUM FULL or CLUSTER anything?
>
> --
> Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
> EnterpriseDB Corporation | fax: 732.331.1301
> 499 Thornall Street, 2nd Floor | jonah.harris@enterprisedb.com
> Edison, NJ 08837 | http://www.enterprisedb.com/
>
--
Regards
Gauri
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 13:08 Devrim GÜNDÜZ <devrim@gunduz.org>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
1 sibling, 1 reply; 12+ messages in thread
From: Devrim GÜNDÜZ @ 2008-07-02 13:08 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: pgsql-performance
On Wed, 2008-07-02 at 18:01 +0530, Gauri Kanekar wrote:
> Checked out the performance of Hot on 30th June :
>
> relname n_tup_ins n_tup_upd n_tup_del
> n_tup_hot_upd
> n_live_tup n_dead_tup *table1* *15509156* *2884653* *0* *2442823*
> *
> 15509158* *68046* table2 434585 718472 0 642336 434703 16723 table3
> 105546
> 252143 0 233078 105402 4922
<snip>
>
> Checked the performance of Hot on 2nd July :
>
> relname n_tup_ins n_tup_upd n_tup_del
> n_tup_hot_upd
> n_live_tup n_dead_tup *table1**15577724* *6237242* *0* *2924948*
> *
> 18460676* *131103* table2 435558 1579613 0 763397 1171497 42476
Maybe those updates were not qualified for HOT between these days?
Regards,
--
Devrim GÜNDÜZ
devrim~gunduz.org, devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
http://www.gunduz.org
Attachments:
signature.asc (application/pgp-signature, 196B) download
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 13:11 Gauri Kanekar <meetgaurikanekar@gmail.com>
parent: Devrim GÜNDÜZ <devrim@gunduz.org>
0 siblings, 2 replies; 12+ messages in thread
From: Gauri Kanekar @ 2008-07-02 13:11 UTC (permalink / raw)
To: Devrim GÜNDÜZ <devrim@gunduz.org>; +Cc: pgsql-performance
How does it indicate if the entries qualify for hot update ??
hot have a limitation that it do not work if, the index column is updated.
But that not the case over here.
On Wed, Jul 2, 2008 at 6:38 PM, Devrim GÜNDÜZ <devrim@gunduz.org> wrote:
> On Wed, 2008-07-02 at 18:01 +0530, Gauri Kanekar wrote:
> > Checked out the performance of Hot on 30th June :
> >
> > relname n_tup_ins n_tup_upd n_tup_del
> > n_tup_hot_upd
> > n_live_tup n_dead_tup *table1* *15509156* *2884653* *0* *2442823*
> > *
> > 15509158* *68046* table2 434585 718472 0 642336 434703 16723 table3
> > 105546
> > 252143 0 233078 105402 4922
> <snip>
> >
> > Checked the performance of Hot on 2nd July :
> >
> > relname n_tup_ins n_tup_upd n_tup_del
> > n_tup_hot_upd
> > n_live_tup n_dead_tup *table1**15577724* *6237242* *0* *2924948*
> > *
> > 18460676* *131103* table2 435558 1579613 0 763397 1171497 42476
>
> Maybe those updates were not qualified for HOT between these days?
>
> Regards,
> --
> Devrim GÜNDÜZ
> devrim~gunduz.org, devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
> http://www.gunduz.org
>
>
--
Regards
Gauri
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 13:29 Jonah H. Harris <jonah.harris@gmail.com>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
1 sibling, 1 reply; 12+ messages in thread
From: Jonah H. Harris @ 2008-07-02 13:29 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
On Wed, Jul 2, 2008 at 9:11 AM, Gauri Kanekar
<meetgaurikanekar@gmail.com> wrote:
> hot have a limitation that it do not work if, the index column is updated.
> But that not the case over here.
Another limitation is that HOT won't work if there's not enough space
to fit the update on the same page.
--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation | fax: 732.331.1301
499 Thornall Street, 2nd Floor | jonah.harris@enterprisedb.com
Edison, NJ 08837 | http://www.enterprisedb.com/
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 13:40 Devrim GÜNDÜZ <devrim@gunduz.org>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
1 sibling, 0 replies; 12+ messages in thread
From: Devrim GÜNDÜZ @ 2008-07-02 13:40 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: pgsql-performance
On Wed, 2008-07-02 at 18:41 +0530, Gauri Kanekar wrote:
> hot have a limitation that it do not work if, the index column is
> updated.
It is one of the conditions -- it also needs to fit in the same block.
Regards,
--
Devrim GÜNDÜZ
devrim~gunduz.org, devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr
http://www.gunduz.org
Attachments:
signature.asc (application/pgp-signature, 196B) download
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 13:44 Gauri Kanekar <meetgaurikanekar@gmail.com>
parent: Jonah H. Harris <jonah.harris@gmail.com>
0 siblings, 1 reply; 12+ messages in thread
From: Gauri Kanekar @ 2008-07-02 13:44 UTC (permalink / raw)
To: Jonah H. Harris <jonah.harris@gmail.com>; +Cc: Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
ok.. But we have set fill_factor = 80 for all the indexes on table1.
Is there a way to check if the page is fill and the update is going on a new
page ??
On Wed, Jul 2, 2008 at 6:59 PM, Jonah H. Harris <jonah.harris@gmail.com>
wrote:
> On Wed, Jul 2, 2008 at 9:11 AM, Gauri Kanekar
> <meetgaurikanekar@gmail.com> wrote:
> > hot have a limitation that it do not work if, the index column is
> updated.
> > But that not the case over here.
>
> Another limitation is that HOT won't work if there's not enough space
> to fit the update on the same page.
>
> --
> Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
> EnterpriseDB Corporation | fax: 732.331.1301
> 499 Thornall Street, 2nd Floor | jonah.harris@enterprisedb.com
> Edison, NJ 08837 | http://www.enterprisedb.com/
>
--
Regards
Gauri
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 14:21 Jonah H. Harris <jonah.harris@gmail.com>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
0 siblings, 1 reply; 12+ messages in thread
From: Jonah H. Harris @ 2008-07-02 14:21 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
On Wed, Jul 2, 2008 at 9:44 AM, Gauri Kanekar
<meetgaurikanekar@gmail.com> wrote:
> ok.. But we have set fill_factor = 80 for all the indexes on table1.
You need fill factor for the heap table, not the index.
> Is there a way to check if the page is fill and the update is going on a new
> page ??
IIRC, I don't think so. I think you'd have to u se something like
pg_filedump to see if you have rows migrated to other blocks due to
updates.
--
Jonah H. Harris, Sr. Software Architect | phone: 732.331.1324
EnterpriseDB Corporation | fax: 732.331.1301
499 Thornall Street, 2nd Floor | jonah.harris@enterprisedb.com
Edison, NJ 08837 | http://www.enterprisedb.com/
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 14:40 Tom Lane <tgl@sss.pgh.pa.us>
parent: Jonah H. Harris <jonah.harris@gmail.com>
0 siblings, 1 reply; 12+ messages in thread
From: Tom Lane @ 2008-07-02 14:40 UTC (permalink / raw)
To: Jonah H. Harris <jonah.harris@gmail.com>; +Cc: Gauri Kanekar <meetgaurikanekar@gmail.com>; Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
"Jonah H. Harris" <jonah.harris@gmail.com> writes:
> On Wed, Jul 2, 2008 at 9:44 AM, Gauri Kanekar
>> Is there a way to check if the page is fill and the update is going on a new
>> page ??
> IIRC, I don't think so.
You could make your application check to see if the page part of a row's
CTID changes when it's updated. But there's no centralized counter
other than the one you are already looking at.
I personally found the original post completely content-free, however,
since it gave no context for the two sets of numbers we were shown.
Over what intervals were the counts accumulated? Were the stats
counters reset after taking the first output, or does the second output
include the first? What exactly does the OP think that "better HOT
performance" is, anyway?
regards, tom lane
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 14:48 Gauri Kanekar <meetgaurikanekar@gmail.com>
parent: Tom Lane <tgl@sss.pgh.pa.us>
0 siblings, 1 reply; 12+ messages in thread
From: Gauri Kanekar @ 2008-07-02 14:48 UTC (permalink / raw)
To: Tom Lane <tgl@sss.pgh.pa.us>; +Cc: Jonah H. Harris <jonah.harris@gmail.com>; Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
2nd count include the 1st count also.
We have not restarted the DB since postgres 8.3 have been released.
Better HOT performance means.... 1st stat showed most of the updated tuples
getting hot.
But the 2nd stat showed that most of the updated tuples are NOT getting hot.
On Wed, Jul 2, 2008 at 8:10 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Jonah H. Harris" <jonah.harris@gmail.com> writes:
> > On Wed, Jul 2, 2008 at 9:44 AM, Gauri Kanekar
> >> Is there a way to check if the page is fill and the update is going on a
> new
> >> page ??
>
> > IIRC, I don't think so.
>
> You could make your application check to see if the page part of a row's
> CTID changes when it's updated. But there's no centralized counter
> other than the one you are already looking at.
>
> I personally found the original post completely content-free, however,
> since it gave no context for the two sets of numbers we were shown.
> Over what intervals were the counts accumulated? Were the stats
> counters reset after taking the first output, or does the second output
> include the first? What exactly does the OP think that "better HOT
> performance" is, anyway?
>
> regards, tom lane
>
--
Regards
Gauri
^ permalink raw reply [nested|flat] 12+ messages in thread
* Re: Hot Issue
@ 2008-07-02 16:35 Tom Lane <tgl@sss.pgh.pa.us>
parent: Gauri Kanekar <meetgaurikanekar@gmail.com>
0 siblings, 0 replies; 12+ messages in thread
From: Tom Lane @ 2008-07-02 16:35 UTC (permalink / raw)
To: Gauri Kanekar <meetgaurikanekar@gmail.com>; +Cc: Jonah H. Harris <jonah.harris@gmail.com>; Devrim GÜNDÜZ <devrim@gunduz.org>; pgsql-performance
"Gauri Kanekar" <meetgaurikanekar@gmail.com> writes:
> Better HOT performance means.... 1st stat showed most of the updated tuples
> getting hot.
> But the 2nd stat showed that most of the updated tuples are NOT getting hot.
Well, as was noted upthread, you'd want to reduce the table fillfactor
(not index fillfactor) below 100 to improve the odds of being able to
do HOT updates. But I wonder whether your application behavior changed.
Are you updating the rows in a way that'd make them wider?
regards, tom lane
^ permalink raw reply [nested|flat] 12+ messages in thread
end of thread, other threads:[~2008-07-02 16:35 UTC | newest]
Thread overview: 12+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2008-07-02 12:31 Hot Issue Gauri Kanekar <meetgaurikanekar@gmail.com>
2008-07-02 12:40 ` Jonah H. Harris <jonah.harris@gmail.com>
2008-07-02 12:41 ` Gauri Kanekar <meetgaurikanekar@gmail.com>
2008-07-02 13:08 ` Devrim GÜNDÜZ <devrim@gunduz.org>
2008-07-02 13:11 ` Gauri Kanekar <meetgaurikanekar@gmail.com>
2008-07-02 13:29 ` Jonah H. Harris <jonah.harris@gmail.com>
2008-07-02 13:44 ` Gauri Kanekar <meetgaurikanekar@gmail.com>
2008-07-02 14:21 ` Jonah H. Harris <jonah.harris@gmail.com>
2008-07-02 14:40 ` Tom Lane <tgl@sss.pgh.pa.us>
2008-07-02 14:48 ` Gauri Kanekar <meetgaurikanekar@gmail.com>
2008-07-02 16:35 ` Tom Lane <tgl@sss.pgh.pa.us>
2008-07-02 13:40 ` Devrim GÜNDÜZ <devrim@gunduz.org>
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