A block size of 8 KB is optimal for most systems. On the other hand, OLTP systems can use smaller block sizes (such as 4K) and DSS systems can use larger block sizes (such as 16K, 32K). Tablespaces that make use of nonstandard block sizes can be determined by using the following below script:
set echo off
feedback off
pagesize 50
linesize 80
spool tblspce_with_non_std_blksize.txt
select Tablespace_Name,block_Size from DBA_TABLESPACES
where Block_Size != (select Value from V$PARAMETER where name = 'db_block_size');
spool off
Sample output of running the above script is shown below:
TABLESPACE_NAME BLOCK_SIZE(K)
------------------------------ ----------
DRSYS 8192
TABLESPC4K 4096
TABLESPC8K 8192
INDX 4096
PROJECTS 8192
TOOLS 16384
USERS 8192
Note: We can query the parameter db_block_size to determine the standard block size in use for a given database. The above output indicates that the nonstandard block sizes in use for the database are as follows:
4KB (tablespaces TABLESPC4K and INDX)8KB (tablespaces DRSYS, TABLESPC8K, PROJECTS,and USERS)
16KB (tablespace TOOLS)
Enjoy :-)
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