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REM rowid_ranges should be at least 21

REM utilize this script help delete large table

REM if update large table  Why not online redefinition or CTAS

-- This scriptspits desired number of rowid ranges to be used for any parallel operations.

-- Best to useit for copying a huge table with out of row lob columns in it or CTAS/copy thedata over db links.

-- This canalso be used to simulate parallel insert/update/delete operations.

-- Maximumnumber of rowid ranges you can get here is 255.

-- Doesn't workfor partitioned tables, but with minor changes it can be adopted easily.

 

-- Doesn'tdisplay any output if the total table blocks are less than rowid ranges times128.

 

-- It can splita table into more ranges than the number of extents

From SaibabuDevabhaktuni http://sai-oracle.blogspot.com/2006/03/how-to-split-table-into-rowid-ranges.html

 

 

 

set verify off

undefinerowid_ranges

undefinesegment_name

undefine owner

set head off

set pages 0

set trimspoolon

 

select'where rowid between ''' ||sys.dbms_rowid.rowid_create(1, d.oid,c.fid1,c.bid1, 0) ||''' and '''||sys.dbms_rowid.rowid_create(1, d.oid, c.fid2, c.bid2, 9999) || '''' ||';'

 from (select distinctb.rn,

                       first_value(a.fid)over(partition by b.rn order by a.fid, a.bid rows between unbounded precedingand unbounded following) fid1,

                       last_value(a.fid)over(partition by b.rn order by a.fid, a.bid rows between unbounded precedingand unbounded following) fid2,

                       first_value(decode(sign(range2- range1),

                                          1,

                                          a.bid +

                                          ((b.rn - a.range1) * a.chunks1),

                                          a.bid))over(partition by b.rn order by a.fid, a.bid rows between unbounded precedingand unbounded following) bid1,

                       last_value(decode(sign(range2 - range1),

                                         1,

                                         a.bid +

                                         ((b.rn - a.range1 + 1) * a.chunks1) - 1,

                                         (a.bid + a.blocks - 1))) over(partition by b.rn order by a.fid, a.bidrows between unbounded preceding and unbounded following) bid2

         from (select fid,

                      bid,

                      blocks,

                      chunks1,

                      trunc((sum2 - blocks + 1 - 0.1) / chunks1)range1,--到前一个区段时有几个分部（rowid_range）

                      trunc((sum2 - 0.1) /chunks1) range2--到本区段时有几个分部（rowid_range）

                 from(select /*+ rule */

                        relative_fno fid,

                        block_id bid,

                        blocks,

                        sum(blocks) over()sum1,

                        trunc((sum(blocks)over()) / &&rowid_ranges) chunks1, --//一个chunks有几个块

                        sum(blocks) over(orderby relative_fno, block_id) sum2           --//到此区段累计的块数

                         from dba_extents

                        where segment_name =upper('&&segment_name')

                          and owner =upper('&&owner'))

                wheresum1 > &&rowid_ranges)a,

              (select rownum - 1 rn

                 from dual

               connect by level <=&&rowid_ranges) b

        where b.rn between a.range1 and a.range2)c,

      (select max(data_object_id) oid

         from dba_objects

        where object_name =upper('&&segment_name')

          and owner = upper('&&owner')

          and data_object_id is not null)d

           /

 

 

 

 

 

 

 

 

-------

select * from (select * from (select *

from  () )a,b)c,d;