SQL & PL/SQL

As per Oracle documentation, it is mentioned that hash partitioning uses oracle hashing algorithms to assign a hash value to each rows partitioning key and place it in the appropriate partition. And the data will be evenly distributed across the partitions. Ofcourse following following conditions :
1. Partition count should follow 2^n logic
2. Data in partition key column should have high cardinality.

I have used hash partitioning in some of our application tables, but data isn't distributed evenly across partitions. To verify it, i performed a small test :

Table script :
Create table ch_acct_mast_hash(
Cod_acct_no number)
Partition by hash(cod_acct_no)
PARTITIONS 128;

Data population script :
declare
i number;
l number;
begin
i := 1000000000000000;
for l in 1 .. 100000 loop
insert into ch_acct_mast_hash values (i);
i := i + 1;
end loop;
commit;
end;

Row-count check :
select count(1) from Ch_Acct_Mast_hash ; --rowcount is 100000

Gather stats script :
begin
dbms_stats.gather_table_stats('C43HDEV', 'CH_ACCT_MAST_HASH');
end;

Data distribution check :
Select min(num_rows), max(num_rows) from dba_tab_partitions
where table_name = 'CH_ACCT_MAST_HASH';

Result is :
min(num_rows) = 700
max(num_rows) = 853

As per the result, it seems there is lot of skewness in data distribution across partitions. Maybe I am missing something, or something is not right.

Can anybody help me to understand this behavior?

Edited by: Kshitij Kasliwal on Nov 2, 2012 4:49 AM