cmds系统数据库源端大表数据更新优化
时间：2021-07-01 10:21:17
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```REM rowid_ranges should be at least 21REM utilize this script help delete large tableREM if update large table Why not online redefinition or CTAS-- This script spits desired number of rowid ranges to be used for any parallel operations.-- Best to use it for copying a huge table with out of row lob columns in it or CTAS/copy the data over db links.-- This can also be used to simulate parallel insert/update/delete operations.-- Maximum number of rowid ranges you can get here is 255.-- Doesn‘t work for partitioned tables, but with minor changes it can be adopted easily.
-- Doesn‘t display any output if the total table blocks are less than rowid ranges times 128.
-- It can split a table into more ranges than the number of extentsFrom Saibabu Devabhaktuni http://sai-oracle.blogspot.com/2006/03/how-to-split-table-into-rowid-ranges.html
set verify offundefine rowid_rangesundefine segment_nameundefine ownerset head offset pages 0set trimspool on
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 distinct b.rn, first_value(a.fid) over(partition by b.rn order by a.fid, a.bid rows between unbounded preceding and unbounded following) fid1, last_value(a.fid) over(partition by b.rn order by a.fid, a.bid rows between unbounded preceding and 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 preceding and 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.bid rows between unbounded preceding and unbounded following) bid2 from (select fid, bid, blocks, chunks1, trunc((sum2 - blocks + 1 - 0.1) / chunks1) range1, trunc((sum2 - 0.1) / chunks1) range2 from (select /*+ rule */ relative_fno fid, block_id bid, blocks, sum(blocks) over() sum1, trunc((sum(blocks) over()) / &&rowid_ranges) chunks1, sum(blocks) over(order by relative_fno, block_id) sum2 from dba_extents where segment_name = upper(‘&&segment_name‘) and owner = upper(‘&&owner‘)) where sum1 > &&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 /
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cmds系统数据库源端大表数据更新优化
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