RE: Performance problem with Shareplex and Oracle

Thu, 23 Oct 2003 15:04:22 -0700

Do you have primary keys etc and hint file? Also do you have constraints disabled. Some

"Nelson, Allan" <[EMAIL PROTECTED]> wrote:
Since the results of triggers firing in the source will appear in the
log files, then in general you do not want the same triggers firing in
the target. Similarly since data integrity is usually enforced in the
source db you can typically disable it in the target. I suppose
something on this order could be the problem.

Allan

-----Original Message-----
Sent: Thursday, October 23, 2003 2:29 PM
To: Multiple recipients of list ORACLE-L


Now we don't use Shareplex, but I do know of others who do & this is not
the first time I hear of performance problems, but I may be able to shed
some light on the problem. Since Shareplex reads the redo logs, if one
statement on the source database affects more than one row (lets say 10
for arguments sake), then shareplex turns it into 10 distinct statements
for the replicated database.! Now imagine that your statement affected
one row in one table, but due to triggers and constraints affected
1000's of other rown in other tables. DAMN, that could make for a REAL
mess on the target system.

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----
Sent: Thursday, October 23, 2003 2:44 PM
To: Multiple recipients of list ORACLE-L


Shareplex is fast here. We replicate a 6 CPU db to a 4 CPU machine
without excessive loads or problems. We run an average of 29 messages
with about 1 GB in the queues. Our data is 0 minutes old.

Outside of contacting Quest support I'm sure of how much help I can be.
When I have seen SP claim as much CPU as you have stated, I have had to
do a shutdown, which kills sp_cop and start it again. This has fixed
the high cpu consumption. SP for us is usually around 18% of a single
CPU. We are processing about 240MB per day of redo.

Sorry not to be! of more help.
Allan

-----Original Message-----
[EMAIL PROTECTED]
Sent: Thursday, October 23, 2003 1:20 PM
To: Multiple recipients of list ORACLE-L


Allan,

I don't know about the source machine.
I receive around 350Megs of data every day.

I'm using sp_ctrl to stop and restart my Post process and monitor the
queue.

I'm pretty sure that the bottleneck come from Shareplex. Oracle is
waiting for Shareplex, we have server's resources available (CPU is 50%
idle).

How can we speed up Shareplex?

Luc

-----Original Message-----
Sent: October 23, 2003 12:56 PM
To: Multiple recipients of list ORACLE-L


How big is the box that is the source for this machine? Have you tried
running sp_ctrl and doing a shutdown and startup?

Allan

-----Original Message-----

Sent: Thursday, October 23, 2003 10:30 AM
To: Multiple recipients of list ORACLE-L


Hi gurus,

Oracle 8.1.7.3 on Sun Solaris
One of our databases has been updated by Shareplex, and we have a huge
performance problem....

Shareplex is the only process running on this database.
Here is the output of v$session_event

SID EVENT TOTAL_WAITS TOTAL_TIMEOUTS TIME_WAITED
AVERAGE_WAIT
-- ------- ----------- -------------- -----------
------------
17 latch free 83 69 1
,012048193
17 log file sync 15 0 9
,6
17 db file sequential read 52 0 6
,115384615
17 file open 1 0 0
0
17 SQL*Net message to client 74791 0 27
,000361006
17 SQL*Net message from client 74791 0 5235
,069995053


I really don't see any Oracle performance problems.....

My problem is the backlog (queue) of Shareplex is getting bigger and
bigger. Where is the bottleneck?

The only thing I can see is the server. The server is a Ultra-80, 2 CPU
450Mhz, 2048Megs of RAM According to "top", this process is taking ! 50%
of the CPU. and my "load average" is 1.26, 1.27, 1.24

My average load exceed 1, can I conclude that the CPU is the bottleneck?

What are my possibilities?

TIA
Luc

---------
Luc Demanche
AstraZeneca R&D Montreal
Oracle Database Administrator
514.832.3200 x2356


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