RE: Are hash sub-partitions balanced?

From: Bobak, Mark <Mark.Bobak_at_proquest.com>
Date: Thu, 2 May 2013 15:31:40 +0000
Message-ID: <33337251867AA34487C91BFA23C52D6501505E_at_BLUPRD0811MB436.namprd08.prod.outlook.com>

What is the nature of the column you're partitioning on? How many unique values does that column have?

-Mark

-----Original Message-----

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Dba DBA Sent: Thursday, May 02, 2013 11:24 AM
To: ORACLE-L
Subject: Re: Are hash sub-partitions balanced?

Followup. So we loaded some skewed data and tihs is a rolliup from my sub-partitions spread across several partitions and I this does not appear to be very well balanced. Is this something I can expect? I am following the power of 2 with 16 hash sub-partitions. I am also going to get more data loaded. I just analyzed the table with granularity='ALL'

select subpartition_position,sum(num_rows) from user_tab_subpartitions
where table_name = '<my table>'
group by subpartition_position
order by 1
/

SUBPARTITION_POSITION SUM(NUM_ROWS)
--------------------- --------------------

                    1               18,337
                    2               32,184
                    3               18,259
                    4               22,271
                    5                6,944
                    6               15,905
                    7               28,929
                    8               41,466
                    9               19,585
                   10               21,391
                   11               23,895
                   12                8,206
                   13               26,849
                   14               12,293
                   15               21,284
                   16                8,395

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http://www.freelists.org/webpage/oracle-l Received on Thu May 02 2013 - 17:31:40 CEST