How to set DB_BLOCK_SIZE and rebuild db if DB_BLOCK_SIZE changed?

[Guest_imported]

In Richard J. Niemiec's paper "Fundamental Tuning Goals: Critical for E-Business" (

http://www.oracle.com/oramag/oracle/00-May/o30tun.html)

he writes:
In addition to adjusting the number of data blocks that the server holds in memory, you can change the size of those blocks by adjusting the setting of the DB_BLOCK_SIZE parameter. DB_BLOCK_SIZE controls the amount of data that the database can read into memory during a single I/O transaction. With Oracle8, you can set this value as high as 32K (16K in pre-Oracle8 releases), but you must rebuild your database if you change the value. Consult the Oracle database tuning and administration manuals before you change this parameter.


By running Richard J. Niemiec's Listing 1:
select name, value from v$parameter
where name in ('db_block_buffers', 'db_block_size',
'shared_pool_size', 'sort_area_size');
I got:
NAME VALUE
-------------------------------------------------------
db_block_buffers 3200
db_block_size 2048
shared_pool_size 20000000
sort_area_size 262144

But I haven't found the DB_BLOCK_SIZE parameter in init.ora file, while the other 3 are in the init.ora file.
I want to enlarge my SGA to suit the increased using.
Can you tell me how should man set DB_BLOCK_SIZE and then rebuild the db?

 

[MikeLacey]

Looks like DB_BLOCK_SIZE is defaulting to 2048. You can set it when you create your database by specifying
[tt]
DB_BLOCK_SIZE = 2048[/tt] (or whatever)

in your initSID.ora file but if you change it later you will have to export the data using [tt]exp[/tt] and read it into a new database that was created with the correct block size already set.
Mike
michael.j.lacey@ntlworld.com