Re: can clustering help INSERTS ?
Someone else cracked it -- he doesn't have TIMED_STATISTICS = TRUE...
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Saturday, October 26, 2002 9:53 PM
*no* waits?
How is this possible?
Is intantaneous computing now a reality?
Sorry for the sarcasm. Wait, no, not really. ;)
Seriously, all databases wait, all operations take
time. The question on everyone's lips is
'How long are *yours* taking?'
Jared
On Saturday 26 October 2002 00:33, Rahul wrote:
the DB is *not* experiencing any waits... i'm trying to bring down the
run
time of the
insertion process, currently it takes around 9 hrs... the management
wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs?
If
you
can locate the sessions in the V$SESSION view, then use the value in
the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better
picture
of where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster
would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
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San Diego, California-- Mailing list and web hosting
services
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Author: Tim Gorman
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Author: Jared Still
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Author: Tim Gorman
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Re: can clustering help INSERTS ?
DENNIS WILLIAMS wrote: Stephane You mentioned each additional index costs about 2.5 times the cost of inserting into a non-indexed table. I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were: - If you can drop all indexes, that will really help inserts. - If you have one index, adding a second index will really hurt, but not as bad. - If the table already has 15 indexes, adding one more index probably won't be noticed. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] Dennis, I have also benched it, and what I gave are my results. Note that we totally agree in _relative_ terms. If you have 15 indexes, I estimate the cost to be about 100 + 15 * 250, so in truth at this stage the cost of an index is about 7% ... Note also that the costs I gave are relative to the number of logical reads. I have met a number of cases when a significant increase in logical reads was hardly noticeable in terms of elapsed time. -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
RE: can clustering help INSERTS ?
Naveen - He provided figures, and they are on the handout that is somewhere in my office. Maybe I'll run across it someday, or even better, maybe he'll publish his results. Here are a few more details that I posted to this list earlier. Kevin Loney (author of Oracle DBA Handbook) has performed index performance tests and presented a paper at our Twin Cities Oracle User's Group (http://www.tcoug.org). I don't know if his paper is on that site or if Kevin has posted it somewhere or if he will included his findings in a future book. His results (from memory) was that there weren't any big surprises. Say it takes 1 hour to load a table with no indexes on it. If you put 1 index on that table, load time will increase about 20% to maybe 1hr 12 minutes (depending on how many columns are indexed, etc.). If we add a second index, load time will again increase, but by a smaller amount than for the first, maybe to 1 hr. 23 minutes. And so it goes. By the time we reach 20 indexes, adding a 21st index may add only 3 or 4 minutes to our load time. There didn't seem to be any point where adding one more index would throw load times into a black hole and double load times or something like that. Kevin also tested whether the size of the index mattered. There were points where say, the 100,000th row caused index performance to suddenly drop, probably due to factors like adding a newer blevel. However it was almost impossible to predict this point ahead of time. My conclusions: - Dropping indexes speeds inserts. - If you have a single index on a table, adding a second index is costly. - If the table already has 20 indexes, one more isn't going to have a noticeable effect. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Saturday, October 26, 2002 3:43 AM To: Multiple recipients of list ORACLE-L Dennis, Did he publish any figures? I mean, it seems common-sense that adding the first index will hurt but adding 11th index to a table won't hurt that much. As stephane pointed out, cost of an index is 2.5 times more than the cost of insert in a non-indexed table. So assuming cost is 1, than cost with 1 index will be 3.5 as 250% increase. Cost with 5 indexes should be 13.5 and cost with 6 indexes will be 16 less than twenty percent increase. Since the addition cost is constant for every index added, the percentage increase in cost (and also maybe time) will be lower and lower. Am I right or missing something? Regards Naveen -Original Message- Sent: Friday, October 25, 2002 11:45 PM To: Multiple recipients of list ORACLE-L Stephane You mentioned each additional index costs about 2.5 times the cost of inserting into a non-indexed table. I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were: - If you can drop all indexes, that will really help inserts. - If you have one index, adding a second index will really hurt, but not as bad. - If the table already has 15 indexes, adding one more index probably won't be noticed. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Friday, October 25, 2002 8:04 AM To: Multiple recipients of list ORACLE-L Rahul wrote: List, i have two heavily inserted tables, the structures are same. currently these tables reside on separate disks, can i increase the performance of inserts if i create these tables in a cluster ? as a cluster would force the rows of both the tables to be physically close on the disk ! regards -rahul Ora 7.3 on AIX You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks). -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: DENNIS
Re: can clustering help INSERTS ?
But even with TIMED_STATISTICS=FALSE, the system will still have waits.
Just because the duration of said waits is not accurately recorded
doesn't mean they do not exist. And if one looks at the V$ wait
interface, the waits will be logged there.
-Mark
On Sun, 2002-10-27 at 09:48, Tim Gorman wrote:
Someone else cracked it -- he doesn't have TIMED_STATISTICS = TRUE...
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Saturday, October 26, 2002 9:53 PM
*no* waits?
How is this possible?
Is intantaneous computing now a reality?
Sorry for the sarcasm. Wait, no, not really. ;)
Seriously, all databases wait, all operations take
time. The question on everyone's lips is
'How long are *yours* taking?'
Jared
On Saturday 26 October 2002 00:33, Rahul wrote:
the DB is *not* experiencing any waits... i'm trying to bring down the
run
time of the
insertion process, currently it takes around 9 hrs... the management
wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs?
If
you
can locate the sessions in the V$SESSION view, then use the value in
the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better
picture
of where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster
would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting
services
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also send the HELP command for other information (like subscribing).
--
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--
Author: Tim Gorman
INET: [EMAIL PROTECTED]
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Author: Jared Still
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Re: can clustering help INSERTS ?
Of course the system will still have waits -- it's just that the query
provided will show values of zero for all of them when TIMED_STATISTICS =
FALSE. That's why Rahul said that there were no waits at all. My bad...
Rahul,
Please enable the parameter TIMED_STATISTICS = TRUE, re-run the INSERT
operations, re-run the query provided in the earlier email, and then post
the results to the list.
You can enable the parameter either by setting the parameter in your
init.ora file and restarting the database instance and then re-running
your INSERT operations, or by simply running ALTER SYSTEM SET
TIMED_STATISTICS = TRUE and the re-running your INSERT operations (without
restarting the database instance). If you choose the latter route, please
be sure to update your init.ora file accordingly for future database
instance startups, as well.
Hope this helps...
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Sunday, October 27, 2002 12:18 PM
But even with TIMED_STATISTICS=FALSE, the system will still have waits.
Just because the duration of said waits is not accurately recorded
doesn't mean they do not exist. And if one looks at the V$ wait
interface, the waits will be logged there.
-Mark
On Sun, 2002-10-27 at 09:48, Tim Gorman wrote:
Someone else cracked it -- he doesn't have TIMED_STATISTICS = TRUE...
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Saturday, October 26, 2002 9:53 PM
*no* waits?
How is this possible?
Is intantaneous computing now a reality?
Sorry for the sarcasm. Wait, no, not really. ;)
Seriously, all databases wait, all operations take
time. The question on everyone's lips is
'How long are *yours* taking?'
Jared
On Saturday 26 October 2002 00:33, Rahul wrote:
the DB is *not* experiencing any waits... i'm trying to bring down
the
run
time of the
insertion process, currently it takes around 9 hrs... the management
wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the
process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the
INSERTs?
If
you
can locate the sessions in the V$SESSION view, then use the value
in
the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query
will
also
mix in CPU statistics from the V$SESSTAT view, to give a better
picture
of where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase
the
performance
of inserts if i create these tables in a cluster ? as a cluster
would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051
http://www.fatcity.com
San Diego, California-- Mailing list and web hosting
services
-
To REMOVE yourself from this mailing list, send an E-Mail
message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and
in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You
may
also send the HELP command for other information (like
subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
RE: can clustering help INSERTS ?
I believe Kevin gave that presentation at OpenWorld -- either last year or the year before. His paper is available for download on the TUSC site, as he works for TUSC. --- DENNIS WILLIAMS [EMAIL PROTECTED] wrote: Naveen - He provided figures, and they are on the handout that is somewhere in my office. Maybe I'll run across it someday, or even better, maybe he'll publish his results. Here are a few more details that I posted to this list earlier. Kevin Loney (author of Oracle DBA Handbook) has performed index performance tests and presented a paper at our Twin Cities Oracle User's Group (http://www.tcoug.org). I don't know if his paper is on that site or if Kevin has posted it somewhere or if he will included his findings in a future book. His results (from memory) was that there weren't any big surprises. Say it takes 1 hour to load a table with no indexes on it. If you put 1 index on that table, load time will increase about 20% to maybe 1hr 12 minutes (depending on how many columns are indexed, etc.). If we add a second index, load time will again increase, but by a smaller amount than for the first, maybe to 1 hr. 23 minutes. And so it goes. By the time we reach 20 indexes, adding a 21st index may add only 3 or 4 minutes to our load time. There didn't seem to be any point where adding one more index would throw load times into a black hole and double load times or something like that. Kevin also tested whether the size of the index mattered. There were points where say, the 100,000th row caused index performance to suddenly drop, probably due to factors like adding a newer blevel. However it was almost impossible to predict this point ahead of time. My conclusions: - Dropping indexes speeds inserts. - If you have a single index on a table, adding a second index is costly. - If the table already has 20 indexes, one more isn't going to have a noticeable effect. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Saturday, October 26, 2002 3:43 AM To: Multiple recipients of list ORACLE-L Dennis, Did he publish any figures? I mean, it seems common-sense that adding the first index will hurt but adding 11th index to a table won't hurt that much. As stephane pointed out, cost of an index is 2.5 times more than the cost of insert in a non-indexed table. So assuming cost is 1, than cost with 1 index will be 3.5 as 250% increase. Cost with 5 indexes should be 13.5 and cost with 6 indexes will be 16 less than twenty percent increase. Since the addition cost is constant for every index added, the percentage increase in cost (and also maybe time) will be lower and lower. Am I right or missing something? Regards Naveen -Original Message- Sent: Friday, October 25, 2002 11:45 PM To: Multiple recipients of list ORACLE-L Stephane You mentioned each additional index costs about 2.5 times the cost of inserting into a non-indexed table. I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were: - If you can drop all indexes, that will really help inserts. - If you have one index, adding a second index will really hurt, but not as bad. - If the table already has 15 indexes, adding one more index probably won't be noticed. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Friday, October 25, 2002 8:04 AM To: Multiple recipients of list ORACLE-L Rahul wrote: List, i have two heavily inserted tables, the structures are same. currently these tables reside on separate disks, can i increase the performance of inserts if i create these tables in a cluster ? as a cluster would force the rows of both the tables to be physically close on the disk ! regards -rahul Ora 7.3 on AIX You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks). -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this
RE: can clustering help INSERTS ?
;-)
the only waits i see are parallel query dequeue wait, and sometimes
v$session_wait shows write complete waits ..
but i'm sure these are not slowing down the process... (or are they ?)
as most of the time v$session_wait does not return a row !!
and i query this view once every second
Rahul
--
From: Jared Still[SMTP:[EMAIL PROTECTED]]
Sent: Sunday, October 27, 2002 8:27 AM
To: [EMAIL PROTECTED]; Rahul
Subject: Re: can clustering help INSERTS ?
*no* waits?
How is this possible?
Is intantaneous computing now a reality?
Sorry for the sarcasm. Wait, no, not really. ;)
Seriously, all databases wait, all operations take
time. The question on everyone's lips is
'How long are *yours* taking?'
Jared
On Saturday 26 October 2002 00:33, Rahul wrote:
the DB is *not* experiencing any waits... i'm trying to bring down the
run
time of the
insertion process, currently it takes around 9 hrs... the management
wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs?
If
you
can locate the sessions in the V$SESSION view, then use the value in
the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better
picture
of where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster
would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
RE: can clustering help INSERTS ?
top waits from system_event, when i siad no waits .. i ment no waits while
querying session_wait !!
offcourse a DB WILL experience waits... but, are these waits slowing down my
inserts ??
these stats are after the insertion of 16 million rows, the table in
question is the only table on that disk
EVENT TOTAL_WAITS TOTAL_TIMEOUTS SEC_WAITED AVERAGE_WAIT
--- --- -- --
parallel query dequeue wait 314695 314824 629392.78
200.000883
db file parallel write281993563850.24
13.6538175
db file sequential read 650214 02681.93
.412468818
buffer busy waits 31427 16 955.09
3.03907468
latch free 1623885 42121 818.44
.050400121
log file parallel write 25338 0 737.44
2.91041124
db file scattered read50131 0 690.79
1.37796972
log file sync 10085 3 144.78
1.43559742
the DB is *not* experiencing any waits... i'm trying to bring down the
run
time of the
insertion process, currently it takes around 9 hrs... the management
wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs?
If
you
can locate the sessions in the V$SESSION view, then use the value in
the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better
picture
of
where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster
would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting
services
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(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Gorman
INET: [EMAIL PROTECTED]
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Author: Rahul
INET: [EMAIL PROTECTED]
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RE: can clustering help INSERTS ?
the DB is *not* experiencing any waits... i'm trying to bring down the run
time of the
insertion process, currently it takes around 9 hrs... the management wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs? If
you
can locate the sessions in the V$SESSION view, then use the value in the
column SID to locate associated rows in the V$SESSION_EVENT view, sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better picture of
where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
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to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Gorman
INET: [EMAIL PROTECTED]
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--
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--
Author: Rahul
INET: [EMAIL PROTECTED]
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RE: can clustering help INSERTS ?
Dennis, Did he publish any figures? I mean, it seems common-sense that adding the first index will hurt but adding 11th index to a table won't hurt that much. As stephane pointed out, cost of an index is 2.5 times more than the cost of insert in a non-indexed table. So assuming cost is 1, than cost with 1 index will be 3.5 as 250% increase. Cost with 5 indexes should be 13.5 and cost with 6 indexes will be 16 less than twenty percent increase. Since the addition cost is constant for every index added, the percentage increase in cost (and also maybe time) will be lower and lower. Am I right or missing something? Regards Naveen -Original Message- Sent: Friday, October 25, 2002 11:45 PM To: Multiple recipients of list ORACLE-L Stephane You mentioned each additional index costs about 2.5 times the cost of inserting into a non-indexed table. I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were: - If you can drop all indexes, that will really help inserts. - If you have one index, adding a second index will really hurt, but not as bad. - If the table already has 15 indexes, adding one more index probably won't be noticed. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Friday, October 25, 2002 8:04 AM To: Multiple recipients of list ORACLE-L Rahul wrote: List, i have two heavily inserted tables, the structures are same. currently these tables reside on separate disks, can i increase the performance of inserts if i create these tables in a cluster ? as a cluster would force the rows of both the tables to be physically close on the disk ! regards -rahul Ora 7.3 on AIX You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks). -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Naveen Nahata INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
Re: can clustering help INSERTS ?
Can you display to the list the output from one of the queries, just for
fun?
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Saturday, October 26, 2002 1:33 AM
the DB is *not* experiencing any waits... i'm trying to bring down the run
time of the
insertion process, currently it takes around 9 hrs... the management wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs? If
you
can locate the sessions in the V$SESSION view, then use the value in the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better picture
of
where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Gorman
INET: [EMAIL PROTECTED]
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San Diego, California-- Mailing list and web hosting services
-
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Author: Rahul
INET: [EMAIL PROTECTED]
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Author: Tim Gorman
INET: [EMAIL PROTECTED]
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RE: can clustering help INSERTS ?
Is timed_statistics set to true?
Regards
Naveen
-Original Message-
Sent: Saturday, October 26, 2002 8:48 PM
To: Multiple recipients of list ORACLE-L
Can you display to the list the output from one of the queries, just for
fun?
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Saturday, October 26, 2002 1:33 AM
the DB is *not* experiencing any waits... i'm trying to bring down the run
time of the
insertion process, currently it takes around 9 hrs... the management wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process
is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs? If
you
can locate the sessions in the V$SESSION view, then use the value in the
column SID to locate associated rows in the V$SESSION_EVENT view,
sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better picture
of
where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
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to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Tim Gorman
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
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Author: Rahul
INET: [EMAIL PROTECTED]
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Author: Tim Gorman
INET: [EMAIL PROTECTED]
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Re: can clustering help INSERTS ?
*no* waits?
How is this possible?
Is intantaneous computing now a reality?
Sorry for the sarcasm. Wait, no, not really. ;)
Seriously, all databases wait, all operations take
time. The question on everyone's lips is
'How long are *yours* taking?'
Jared
On Saturday 26 October 2002 00:33, Rahul wrote:
the DB is *not* experiencing any waits... i'm trying to bring down the run
time of the
insertion process, currently it takes around 9 hrs... the management wants
to bring it
down to 5-6 hrs...again.. i OD NOT see any wait events while the process is
running..
there are no indexes on the tables
--
From: Tim Gorman[SMTP:[EMAIL PROTECTED]]
Reply To: [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 9:13 PM
To: Multiple recipients of list ORACLE-L
Subject:Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs? If
you
can locate the sessions in the V$SESSION view, then use the value in the
column SID to locate associated rows in the V$SESSION_EVENT view, sorting
by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time
cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will
also
mix in CPU statistics from the V$SESSTAT view, to give a better picture
of where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
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to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
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(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
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Author: Tim Gorman
INET: [EMAIL PROTECTED]
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---
--
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Author: Jared Still
INET: [EMAIL PROTECTED]
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Re: can clustering help INSERTS ?
Rahul wrote: List, i have two heavily inserted tables, the structures are same. currently these tables reside on separate disks, can i increase the performance of inserts if i create these tables in a cluster ? as a cluster would force the rows of both the tables to be physically close on the disk ! regards -rahul Ora 7.3 on AIX You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks). -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
Re: can clustering help INSERTS ?
Rahul,
It does no good to speculate; let's work with facts...
What wait-events are occurring in the sessions running the INSERTs? If you
can locate the sessions in the V$SESSION view, then use the value in the
column SID to locate associated rows in the V$SESSION_EVENT view, sorting by
the cumulative time spent on each wait-event:
selectevent, time_waited, average_time, max_time
fromv$session_event
wheresid = SID
union
selectn.name, s.value, 0, 0
fromv$sesstat s, v$statname n
wheres.sid = SID
andn.name in ('CPU used by this session','parse time cpu','recursive
cpu usage')
ands.statistic# = n.statistic#
order by 2 desc
As you can see, in addition to wait-event information, this query will also
mix in CPU statistics from the V$SESSTAT view, to give a better picture of
where time is being spent by these sessions...
Can you post the results of these queries back to the list?
Thanks!
-Tim
- Original Message -
To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED]
Sent: Friday, October 25, 2002 6:18 AM
List,
i have two heavily inserted tables, the structures are same.
currently these tables reside on separate disks, can i increase the
performance
of inserts if i create these tables in a cluster ? as a cluster would
force
the rows of both the tables
to be physically close on the disk !
regards
-rahul
Ora 7.3 on AIX
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Rahul
INET: [EMAIL PROTECTED]
Fat City Network Services-- 858-538-5051 http://www.fatcity.com
San Diego, California-- Mailing list and web hosting services
-
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
--
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Author: Tim Gorman
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RE: can clustering help INSERTS ?
Stephane You mentioned each additional index costs about 2.5 times the cost of inserting into a non-indexed table. I just wanted to point out that Kevin Loney has done some performance tests involving the number of indexes. I don't know if he has published these anywhere. In a nutshell, the results were that a single index really hurts insert performance, and each additional index increases the hurt, but by a decreasing amount. The conclusions were: - If you can drop all indexes, that will really help inserts. - If you have one index, adding a second index will really hurt, but not as bad. - If the table already has 15 indexes, adding one more index probably won't be noticed. Dennis Williams DBA, 40%OCP Lifetouch, Inc. [EMAIL PROTECTED] -Original Message- Sent: Friday, October 25, 2002 8:04 AM To: Multiple recipients of list ORACLE-L Rahul wrote: List, i have two heavily inserted tables, the structures are same. currently these tables reside on separate disks, can i increase the performance of inserts if i create these tables in a cluster ? as a cluster would force the rows of both the tables to be physically close on the disk ! regards -rahul Ora 7.3 on AIX You would also increase contention ... I'd rather try to augment the number of free lists, and, if you are lucky enough not to access your indexes in RANGE SCAN mode, to create them as REVERSE. Beware of indexes, by the way, each additional index costs about 2.5 times the cost of inserting into a non-indexed table (in terms of logical blocks). -- Regards, Stephane Faroult Oriole Software -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Stephane Faroult INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: DENNIS WILLIAMS INET: [EMAIL PROTECTED] Fat City Network Services-- 858-538-5051 http://www.fatcity.com San Diego, California-- Mailing list and web hosting services - To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
