RAC problem, is gc_files_to_locks is needed?
- From: tomi wijanto <restomi_w@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Wed, 20 Oct 2004 20:20:49 -0700 (PDT)
Hi All,
I has oracle9i database with RAC using 2 nodes.
The first time i used them, i activated server load
balancing, so user connect to least loaded instance.
But after i checked 'gcs/ges wait' related to cache
fusion, that is very large, i activate only one node,
and use another node as failover node.
What i expected here was, i want to reduce
intercluster operations for sql/dml.
The problem i still got was, when one table was
actively update by many users and i did full table
scan on it, it's quite slow. I have compared it with
non-RAC database, it's about 2-3 times slower.
I have activated sql trace, and found many2 of 'global
cr request' wait on that full table scan.
So i feel a little confuse now. I guess when providing
consistent view of updated blocks, the active node
still check for existency of those blocks in another
instance (that should be failed because the node is
pasive), and then read from undo segments. That is
probably why non-RAC database got faster.
The question is: How could i reduce intercluster
operation in full table scan. I have read about
gc_files_to_locks parameter, but i'm afraid of
inflexibility caused by it (that i need to bounce
server to change it).
Is there any best practice to use gc_files_to_locks?
I'm really curious on this parameter and wondering if
it's worthed to considered..
Best regards,
tomi
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