Tip

Top 30 I/Os on your SAP System

Sometimes it is worth identifying the top few SQL statements working on your SAP system. Fine-tuning these SQL statement have done wonders for the performance of our systems. Try executing the attached script on your development system with Oracle before taking it to your productive system.
To be executed under SQLPLUS with user INTERNAL:
SQL Code :
==========
-- Top 30 I/o Intesive SQL Statements Identification : top30IO.sql
set linesize 80
set pagesize 58
set heading  on
set serveroutput on

spool top30iosql.txt

declare
        cursor curs1 is
              from v$sqlarea order by disk_reads / decode(executions,0,1,executions) desc;
        stmnt_ctr number(3);
        wrt1 number(3);

begin
        dbms_output.enable(50000);
              exit;
           end if;

:q!
ie0107:oraipd> cat top30iosql.sql
-- Top 30 I/o Intesive SQL Statements Identification : top30iosql.sql
set linesize 80
set pagesize 58
set heading  on
set serveroutput on

spool top30iosql.txt

declare
        cursor curs1 is
              select executions, disk_reads, buffer_gets, first_load_time, sql_text
              from v$sqlarea order by disk_reads / decode(executions,0,1,executions) desc;
        stmnt_ctr number(3);
        wrt1 number(3);

begin
        dbms_output.enable(50000);
        stmnt_ctr := 0;

        for inrec in curs1 loop
           stmnt_ctr := stmnt_ctr + 1;
           if stmnt_ctr >= 31 then
              exit;
           end if;

           dbms_output.put_line('--------------------------------------'

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|| '--------------------------------------'); dbms_output.put_line('SQL Stmnt Number: ' || to_char(stmnt_ctr)); dbms_output.put_line('--------------------------------------' || '--------------------------------------'); dbms_output.put_line('Executions : ' || to_char(inrec.executions)); dbms_output.put_line('Disk Reads : ' || to_char(inrec.disk_reads) || ' Buffer Gets : ' || to_char(inrec.buffer_gets)); dbms_output.put_line('First Load Time: ' || inrec.first_load_time); dbms_output.put_line('SQL Statement-------->'); wrt1 := 1; while wrt1 <= ceil(length(inrec.sql_text) / 72) loop dbms_output.put_line('.....' || substr(inrec.sql_text,((wrt1-1)*72)+1,72)); wrt1 := wrt1 + 1; end loop; dbms_output.put_line('--------------------------------------' || '--------------------------------------'); dbms_output.put_line(' '); end loop; end; / spool off set serveroutput off set termout on
Now edit/view the output file top30iosql.txt in suitable viewer of your O/S and do the fine tuning from there. Good luck!

This was first published in September 2003

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