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DSNTIAUL performance

 
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mlp

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Joined: 23 Sep 2005
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PostPosted: Tue Jan 24, 2012 4:40 pm    Post subject: DSNTIAUL performance
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I am using the DSNTIAUL to extract data corresponding to a select query. The query is a join query of multiple tables. It takes lot of time to execute the job which executes the query using DSNTIAUL utility.

I tried to tune the query and measured extent of improvement with EXPLAIN. I actually did get lot of improvement but once I executed job with new query, it took more time as that of the old query.

Can somebody explain me this behaviour?
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Pandora-Box

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PostPosted: Tue Jan 24, 2012 4:50 pm    Post subject:
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As your own work try to look if the SQL is getting a cartesian product

Try to revisit your query if the table indexes have been used effectively

and who knows even an index at a wrong place could screw it up all

Suggest you to sit with your DBA try to explain him the scenario he might be knowing the system better

As its hard to give a suggesion/solution without looking into Table,columns,Index,SQL and ofcourse the EXPLAIN report
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mlp

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PostPosted: Tue Jan 24, 2012 5:30 pm    Post subject:
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The explain analysis shows that there is roghly 70% improvement in query performance in terms of CPU ms consumed and service units consumed.

If explain is showing me 70% of improvement then I think performance of the unload job should really improve. At least a bit. But once I executed the tuned query with DSNTIAUL then the job take more time. That is why I am puzzled.
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enrico-sorichetti

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PostPosted: Tue Jan 24, 2012 5:33 pm    Post subject: Reply to: DSNTIAUL performance
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Quote:
it took more time

if You are talking about elapsed meditate on the factors that influence it
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Pandora-Box

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PostPosted: Tue Jan 24, 2012 7:13 pm    Post subject:
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Just to add on check with your DBA if RUNSTATS has been done recently
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mlp

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PostPosted: Wed Jan 25, 2012 2:08 pm    Post subject:
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Not only the ELAPS time has increased but the CPU consumption is also increased.

The ealier query was doing tablespace scan for one of the query block. I just added few predicates to WHERE clause so that the table space scan got converted into index scan. Also the as I said earlier the consumed CPU ms also reduced.

Is there any other factor influencing the perfromance of the same query which is executed by DSNTIAUL?
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mlp

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PostPosted: Wed Jan 25, 2012 2:20 pm    Post subject:
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Below the explain report regarding the same.

Before -

Code:


      Query Q   Pl M Ac M  I T                     
     Number Bl  No T Ty Co O No  Table Name       
          * *   *  * *  *  * *   *                 
----------- --  -- - -- -- - --  ------------------
      98980 1   1  3    0    0                     
      98980 2   1  0 R  0  N 1   T1           
      98980 2   2  1 I  2  N 2   T2           
      98980 3   1  0 I  5  N 3   T3           
      98980 4   1  0 I  5  N 4   T4           
      98980 5   1  0 I  5  Y 5   T5           
      98980 6   1  0 I  5  Y 6   T6           
      98980 7   1  0 R  0  N 7   T1           
      98980 7   2  1 I  1  Y 8   T2           
      98980 8   1  0 I  5  N 9   T3           
      98980 9   1  0 I  5  N 10  T4           
      98980 10  1  0 I  5  Y 11  T5           
      98980 11  1  0 I  5  Y 12  T6           

      Query  Stmt   C   Estimated   Estimated             
     Number  Type   C Serv. Units    Proc. ms Reason       
          *  *      *           *           * *           
-----------  ------ - ----------- ----------- -------------
      98980  SELECT A    84757904     1525642             



After -

Code:

      Query Q   Pl M Ac M  I T                   
     Number Bl  No T Ty Co O No  Table Name       
          * *   *  * *  *  * *   *                 
----------- --  -- - -- -- - --  ------------------
      98980 1   1  3    0    0                     
      98980 2   1  0 I  1  N 1   T1           
      98980 2   2  1 I  2  N 2   T2           
      98980 3   1  0 I  5  N 3   T3           
      98980 4   1  0 I  5  N 4   T4           
      98980 5   1  0 I  5  Y 5   T5           
      98980 6   1  0 I  5  Y 6   T6           
      98980 7   1  0 I  1  N 7   T1           
      98980 7   2  1 I  1  Y 8   T2           
      98980 8   1  0 I  5  N 9   T3           
      98980 9   1  0 I  5  N 10  T4           
      98980 10  1  0 I  5  Y 11  T5           
      98980 11  1  0 I  5  Y 12  T6           


      Query Stmt   C   Estimated   Estimated             
     Number Type   C Serv. Units    Proc. ms Reason       
          * *      *           *           * *           
----------- ------ - ----------- ----------- -------------
      98980 SELECT A    26165840      470986             

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