55 lines
1.2 KiB
SQL
55 lines
1.2 KiB
SQL
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--
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-- File name: demos/cse.sql
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--
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-- Purpose: Advanced Oracle Troubleshooting Seminar demo script
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--
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-- Demonstrating common subexpression elimination transformation
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--
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-- Author: Tanel Poder ( http://www.tanelpoder.com )
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--
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-- Copyright: (c) 2007-2009 Tanel Poder
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--
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--------------------------------------------------------------------------------
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set serverout on size 1000000
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create or replace function imhere( par in varchar2 )
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return varchar2
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as
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begin
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dbms_output.put_line('i''m here!: '||par);
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return par;
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end;
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/
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@pd eliminate_common_subexpr
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set echo on
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select /*+ ORDERED_PREDICATES tanel1 */ *
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from dual
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where
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(imhere(dummy) = 'X' and length(dummy) = 10)
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or (imhere(dummy) = 'X' and length(dummy) = 11)
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/
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alter session set "_eliminate_common_subexpr"=false;
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select /*+ ORDERED_PREDICATES tanel2 */ *
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from dual
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where
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(imhere(dummy) = 'X' and length(dummy) = 10)
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or (imhere(dummy) = 'X' and length(dummy) = 11)
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/
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set echo off
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select /*+ tanel3 */ *
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from dual
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where
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(imhere(dummy) = 'X' and length(dummy) = 10)
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or (imhere(dummy) = 'X' and length(dummy) = 11)
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/
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