FreeLists / oracle-l / RE: Row cache lock wait issue in RAC

["Luca Canali" <Luca.Canali@xxxxxxx>]

Hi Dimitre,

I haven't tried yet to use separate tablespaces, it looks like a good
solution although a bit unpractical for my system (without
reengineering), because I would end up with a very large number of
tablespaces in a 
short time.

As for you previous suggestion of assigning a fixed quota to the user, I
didn't mention it in my mail but we had tried it without success.

By the way, I would be quite interested to know why oracle needs to
acquire row cache lock on dc_tablespace_quotas in this case and if there
is any way to skip this operation with 'a clever hack'.

Thanks,
L.


-----Original Message-----
From: Radoulov, Dimitre [mailto:cichomitiko@xxxxxxxxx] 
Sent: Thursday, June 01, 2006 9:10 AM
To: Luca Canali
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Row cache lock wait issue in RAC

>I am stress testing an application that performs massive inserts (logs

>tons of data) into Oracle tables using direct path insert. Multiple  
>tables are used to provide scalability (each log source inserts into a

>dedicated table). This application uses direct path inserts and 
>bypasses  the cache so I can see that it also scales in RAC (10g RAC, 6
nodes).
> 
> BUT increasing the number of log sources I have now started to see the

> following bottleneck: row cache wait (on dc_tablespace_quotas), for 
> example from a 10046 trace:
> ---------------------------
> WAIT #19: nam='row cache lock' ela= 2888862 cache id=5 mode=0 
> request=5
> obj#=76647 tim=1122164147766228
> WAIT #19: nam='row cache lock' ela= 2824967 cache id=5 mode=0 
> request=5
> obj#=76647 tim=1122164150591291
> 
> It looks to me as row cache lock contention between direct path 
> inserts, probably made worse by rac/GES. (Note also that I don't 
> enforce tablespace quotas (the application owner has unlimited
tablespace).
> 
> Any ideas on how to tune this?

You can also try to put the tables in different tablespaces. 


Regards
Dimitre
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