Message
hi there
database is 400GB, about 30 GB of new data in
and 30 aged out.
tables that si causing the chaining are very
active in ypdate and deletes and all vey variable length. with the 8K
block size we had at min 7% row chaining that now decreased to 1 %
(problem is actually further caused by the fact that the large tables,
5GB + also has believe it or not 700 columns +)
ye ye, if i was to redo DB then would redo it
as a complete 16K block size. the little space wastage for the small
tables would def be worth the trde of from running mutiple block size.
as for memory on the server, V880 8 CPU + 16
GB ram of which we are currently only using 6 GB (64bit sparc config)
tied to a ok'ish performing/Configured EMC SAN.
George
________________________________________________
George Leonard
Oracle Database Administrator
Dimension Data (Pty) Ltd
(Reg. No. 1987/006597/07)
Tel: (+27 11) 575 0573
Fax: (+27 11) 576 0573
E-mail:george.leonard@xxxxxxxxxxxxx
Web: http://www.didata.co.za
You Have The Obligation to Inform One Honestly of the
risk, And As a Person
You Are Committed to Educate Yourself to the Total Risk In Any Activity!
Once Informed & Totally Aware of the Risk,
Every Fool Has the Right to Kill or Injure Themselves
as They See Fit!
OK -- so it is all about avoiding row
chaining... I think I would still try to choose one block size for your
database, and take some chaining for granted. the problem with multiple
block sizes is that you have to segment your available SGA memory,
resulting in less efficiency and more maintenance. It is a great
feature, but it was never intended as a performance
feature, although the thought may seem appealing. It is meant to open
up transportable tablespaces possibilities.
are the rows of these wide tables all fixed
length? and are all columns defined as NOT NULL? maybe the 8KB block
size would be good enough ... and the advantages of a single block size
would outweigh the disadvantages of some chaining. after all, reading a
single 16 KB block is not that much cheaper than reading two 8 KB
blocks, certainly not when part of a multi-block I/O scan ...
cheers,
Lex.
hi there
firstly the database was created as a 8k
block size, I have always found this a very good block size to use.
but I do have some very wide tables and I
mean very wide that just ended up better on a 16K block. so I am using
/oracle9 feature of mutiple block sizes depended on data requirements.
George
________________________________________________
George Leonard
Oracle Database Administrator
Dimension Data (Pty) Ltd
(Reg. No. 1987/006597/07)
Tel: (+27 11) 575 0573
Fax: (+27 11) 576 0573
E-mail:george.leonard@xxxxxxxxxxxxx
Web: http://www.didata.co.za
You Have The Obligation to Inform One Honestly of the
risk, And As a Person
You Are Committed to Educate Yourself to the Total Risk In Any Activity!
Once Informed & Totally Aware of the Risk,
Every Fool Has the Right to Kill or Injure Themselves
as They See Fit!
Hi George,
as far as I know, this is impossible. may I
ask why you have two different block sizes in a single database?
kind regards,
Lex.
Hi all
I have a mix of 8K and 16K tablespaces.
As such I have configured a 8K and 16K cache pool via:db_cache_size and
db_16k_cache_size.
I have thus far configured a kep pool via db_keep_cache_size, but I am
guessing this will only be used for the default block size being 8K.
How do I configure (what si the parameter name) for a 16K keep pool ?
thanks
George
________________________________________________
George Leonard
Oracle Database Administrator
Dimension Data (Pty) Ltd
(Reg. No. 1987/006597/07)
Tel: (+27 11) 575 0573
Fax: (+27 11) 576 0573
E-mail:george.leonard@xxxxxxxxxxxxx
Web: http://www.didata.co.za
You Have The Obligation to Inform One Honestly of the risk, And As a
Person
You Are Committed to Educate Yourself to the Total Risk In Any Activity!
Once Informed & Totally Aware of the Risk,
Every Fool Has the Right to Kill or Injure Themselves as They See Fit!
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