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Message Posted: Mon, 22 Nov 2004 @ 23:19:50 GMT


     
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Subj:   Quesion on Explain plan on "Create a new table"
 
From:   akleema_talukder

When I do a explain on a " create table " I see in the explain plan two steps which I do not understand reason behind it. I highlighted these two steps below. We know that we see "AMP ABORT test " which caused by an ABORT or ROLLBACK statement . My question is: Why do we see these steps in the Create table statements?"

I will appreciate if anybody gives me any hints for the reason behind it.

     explain CREATE SET TABLE GDYR_EDW.CO_Test ,NO FALLBACK ,
          NO BEFORE JOURNAL,
          NO AFTER JOURNAL
          (
           CO_CD CHAR(4) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
           SBU_ID BYTEINT,
           EFF_DT DATE FORMAT 'YYYY-MM-DD' NOT NULL,
           JNT_VENTURE_IND CHAR(1) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL COMPRESS 'N',
            TERR_NAME VARCHAR(35) CHARACTER SET LATIN NOT CASESPECIFIC NOT NULL,
           EDW_JOB_ID INTEGER NOT NULL)
     PRIMARY INDEX ( CO_CD );

Explain Plan:

Explanation
--------------------------------------------------
 
  1)First, we lock GDYR_EDW.CO_Test for exclusive use.  
  2)Next, we lock a distinct DBC."pseudo table" for write on a RowHash for deadlock prevention, we lock a distinct DBC."pseudo table" for write on a RowHash for deadlock prevention, we lock a distinct DBC."pseudo table" for read on a RowHash for deadlock prevention, and we lock a distinct DBC."pseudo table" for write on a RowHash for deadlock prevention.  
  3)We lock DBC.AccessRights for write on a RowHash, we lock DBC.TVFields for write on a RowHash, we lock DBC.TVM for write on a RowHash, we lock DBC.DBase for read on a RowHash, and we lock DBC.Indexes for write on a RowHash.  
  4)We execute the following steps in parallel.  
   
  1) We do a single-AMP ABORT test from DBC.DBase by way of the unique primary index.
 
   
  2) We do a single-AMP ABORT test from DBC.TVM by way of the unique primary index.
 
   
  3) We do an INSERT into DBC.TVFields (no lock required).
 
   
  4) We do an INSERT into DBC.TVFields (no lock required).
 
   
  5) We do an INSERT into DBC.TVFields (no lock required).
 
   
  6) We do an INSERT into DBC.TVFields (no lock required).
 
   
  7) We do an INSERT into DBC.TVFields (no lock required).
 
   
  8) We do an INSERT into DBC.TVFields (no lock required).
 
   
  9) We do an INSERT into DBC.Indexes (no lock required).
 
   
  10) We do an INSERT into DBC.TVM (no lock required).
 
   
  11) We INSERT default rights to DBC.AccessRights for GDYR_EDW.CO_Test.
 
  5)We create the table header.  
  6)Finally, we send out an END TRANSACTION step to all AMPs involved in processing the request.  
  ->No rows are returned to the user as the result of statement 1.  


thanks,

Akleema



     
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