Initial Extent Size of a Partition Changed to 8MB from 64KB After Upgrade to 11.2.0.2 or Later

This feature is controlled by _partition_large_extents for tables and _index_partition_large_extents for indexes

set linesize 210
col "Parameter" format a30
col "Session Value" format a20
col "Instance Value" format a20
col "Desc" format a70
select a.ksppinm  "Parameter", c.ksppstvl "Instance Value", ksppdesc "Desc"
from sys.x$ksppi a, sys.x$ksppcv b, sys.x$ksppsv c
where a.indx = b.indx and a.indx = c.indx
and substr(ksppinm,1,1)='_'
and a.ksppinm like ('%_partition_large_extents');

Parameter                      Instance Value   Desc
------------------------------ ---------------- -------------------------------------------------------
_partition_large_extents       TRUE             Enables large extent allocation for partitioned tables 
_index_partition_large_extents TRUE              Enables large extent allocation forpartitioned indices

The details of the behavior change are available in the below metalink.

Doc ID 1295484.1 — Initial Extent Size of a Partition Changed to 8MB from 64KB After Upgrade to 11.2.0.2 or Later.