Re: Interpretation of TKPROF output

Peter,

In the perfect world you would expect the two explain plans (don't worry about the different headings) to be identical. Someone can probably answer this precisely but the first one is created during the trace and the second one is provided because you supplied the "explain=user/pass" option to tkprof - it basically says "go back and get an explain plan for each query".

Are you sure that both explain plans are generated using the same username on the same instance? Is one perhaps connecting to a different database such as development? In essence - if you run "sqlplus user/pass" from the same place you ran tkprof are you connected to the exact same location as the session that created the trace file?

Unfortunately if you are connected to the same area then I cannot help much more. Perhaps try taking the statement and use autotrace in sqlplus to see which plan it provides. Perhaps row level security of something is kicking in and modifying the query (this caught us out once when explain plans changed because we were connected as a different user)?

Regards,

     Mark.

                                                                                                                       
                    "Schauss, Peter"                                                                                   
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                    14/10/02 06:03                                                                                     
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I am running tkprof on some trace files with the following options: (Oracle 8.1.7)

explain=<user>/<password> sort=exeqry,fchqry,execu,fchcu

Output after each query includes the following two tables:

Rows Row Source Operation

-------  ---------------------------------------------------
     36  INLIST ITERATOR
     36   TABLE ACCESS BY INDEX ROWID PART_LIST
     72    INDEX RANGE SCAN (object id 3451)


Rows     Execution Plan
-------  ---------------------------------------------------
      0  SELECT STATEMENT   GOAL: CHOOSE
     36   TABLE ACCESS   GOAL: ANALYZED (FULL) OF 'PART_LIST'

The "Execution Plan" table corresponds to the Explain Plan section of the Performance manual. There is no mention, however, of the "Row Source Operation" table. I note particularly, that in some cases the first table seems to agree with the second. In others, however, such as the example here, the Row Source table shows use of an index while the Execution Plan shows a Table Access (Full table scan?).

Am I interpreting this correctly? If so, what is going on?

Thanks,

Peter Schauss
Northrop Grumman Corporation
schaupe_at_mail.northgrum.com

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